Horticulture

Previous efforts to develop rough allometric woody biomass equations for vines notwithstanding, there is still a need to improve our precision in estimating of how biomass changes with different parameters. Because the present analysis was conducted for 15 year old Cabernet vines, there is now a need for calibrating how vine C varies with age, varietal and training system. There is also uncertainty around the influence of grafting onto root stock on C accumulation in vines. As mentioned in the methods, the vines in this study were not grafted—an artifact of the root-limiting duripan approximately 50 cm below the soil surface. The site’s location on the flat, valley bottom of a river floodplain also means that its topography, while typical of other vineyard sites perse, created conditions that limit soil depth, drainage and decomposition. As such, the physical conditions examined here may differ significantly from more hilly regions in California, such as Sonoma and Mendocino counties. Similarly, the lack of a surrounding natural vegetation buffer at this site compared to other vineyards may mean that the ecological conditions of the soil communities may or may not have been broadly typical of those found in other vineyard sites. Thus, to the extent that future studies can document the degree to which such parameters influence C accumulation in vines or across sites, hydroponic nft they will improve the accuracy and utility of C estimation methods and enable viticulturists to be among the first sectors in agriculture for which accurate C accounting is an industry wide possibility.

The current study was also designed to complement a growing body of research focusing on soil-vine interactions. Woody carbon reserves and sugar accumulation play a supportive role in grape quality, the main determinant of crop value in wine grapes. The extent to which biomass production, especially in below ground reservoirs, relates to soil carbon is of immediate interest for those focused on nutrient cycling, plant health and fruit production, as well as for those concerned with C storage. The soil-vine interface may also be the area where management techniques can have the highest impact on C stocks and harvest potential. We expect the below ground estimates of root biomass and C provided here will be helpful in this regard and for developing a more thorough understanding of below ground C stores at the landscape level. For example, Williams et al. estimated this component to be the largest reservoir of C in the vineyard landscape they examined, but they did not include root biomass in their calculations. Others have assumed root systems to be ~30% of vine biomass based on the reported biomass values for roots, trunk, and cordons. With the contribution of this study, the magnitude of the below ground reservoir can now be updated.Grapes are the most valuable fruit crop in the United States, valued at over $6.5 billion annually , but climate change is projected to reduce grape production and quality . Climate affects grape quality by impacting the concentration of sugars, organic acids, and secondary compounds .

The climatic conditions producing the highest quality wine cause the berries to reach optimal ratios between sugar and acid concentrations and maximum concentrations of pigment, aroma, and flavor compounds simultaneously . Hot temperatures accelerate sugar accumulation, forcing growers to harvest earlier, before berries reach optimal flavor development, to avoid the high alcohol content and insipid wine flavor from excessive sugar to acid ratios . Harvest dates have shifted earlier historically, and climate models predict further acceleration of ripening . Growers can partly compensate through management practices, such as trimming canopies or using shade clothes to reduce the ratio of sugar supply to demand , though these practices are costly and increasingly ineffective in the face of climate change . Planting existing cultivars or developing new cultivars with slower sugar accumulation are promising alternative strategies to mitigate these climate change impacts, but these efforts have been hindered by uncertainty around the plant traits controlling sugar accumulation . Grape cultivars vary in berry maturation and sugar accumulation rates, and in their response to abiotic stress, but the main anatomical and physiological mechanisms driving these differences remain unknown .

Multiple physiological processes influence berry sugar accumulation and its responses to climate, including photosynthesis, long-distance sugar transport, and local transport and metabolism in the berries . However, the relative importance of these factors in regulating sugar concentrations and fruit growth is debated . Photosynthetic responses to heat and water stress could impact cultivar differences in accumulation rates by affecting the sugar supply for ripening . Further, sugar is transported from the photosynthesizing leaves to the berries through the sugar-conducting vascular tissue – the phloem. At the onset of ripening , the berries significantly accelerate sugar accumulation by initiating active sugar unloading from the phloem, making the phloem the primary pathway for water and resource influx into the berries . The importance of phloem transport to ripening suggests that phloem traits could be important drivers of cultivar differences in sugar accumulation, and that modifying phloem traits to slow sugar accumulation under hot conditions could help mitigate the impacts of climate change on wine quality. However, the main traits controlling sugar accumulation in grape remain unclear . The rate of phloem transport is determined by both the hydraulic resistance to the flow of sugar sap, and the activity and kinetics of water and sugar transporters in the sources, sinks, and along the transport pathway . Modeling studies suggest that increasing the hydraulic resistance of the phloem reduces sugar export to the sinks . Therefore, selecting grape cultivars with lower total phloem conductance could decelerate sugar accumulation and improve the synchronization of sugar accumulation with flavor development under hotter conditions. However, a higher hydraulic resistance can make the phloem more susceptible to declines or even complete failures in transport under severe water stress . Thus, we expect cultivars that produce high-quality wine in hot, dry conditions to exhibit phloem hydraulic resistances that slow berry sugar accumulation while avoiding phloem failure. The phloem transport pathway is composed of individual sugar-conducting cells with porous end walls stacked to form conduits . The anatomy of the transport pathway, including the total cross-sectional area of sieve tubes in plant organs, lumen area of individual sieve tubes, and porosity of the sieve plates, significantly impacts pathway resistance . Plants with a greater cross-sectional area dedicated to phloem , sieve tubes with wider lumen areas , and larger and more abundant pores in the sieve plates are expected to have a lower hydraulic resistance . Total phloem cross-sectional area in the shoots has been found to vary between several grape cultivars , hydroponic channel and a greater cross-sectional phloem area has been linked to faster sugar accumulation in the fruit in other crop species . However, the variation of phloem structural traits across cultivars adapted to a diverse range of climatic conditions and the relationship of these traits to sugar accumulation is largely unknown for grapevines. Establishing these anatomical links could allow breeders to modify sugar accumulation by selecting for phloem traits, instead of management practices that can negatively impact the fruit zone environment or yield . In this study, we used a common garden experiment to evaluate the links between phloem anatomy and sugar accumulation across 18 winegrape cultivars typically grown in climatically diverse grape growing regions. We assessed phloem and xylem vascular anatomy in leaf petioles and midveins and berry pedicels, to capture hydraulic resistance along the long-distance transport pathway. We also measured maximum berry sugar accumulation rates in the post-veraison ripening period to capture the greatest capacity for sugar transport . We predicted that traits that reduce hydraulic resistance, including larger total cross-sectional phloem areas, larger mean lumen areas for individual sieve tubes, and more porous sieve plates would increase maximum sugar accumulation rates. We also predicted that cultivars typically grown in hotter wine regions would havetraits that increase hydraulic resistance, as an adaptation to increase wine quality by reducing the rate of sugar accumulation. In addition, we measured photosynthesis and vine water stress to compare the impacts of phloem anatomy, vine carbon supply, and vine water status on sugar accumulation rates. Overall, our goals were to determine the most influential traits for sugar accumulation in grape berries and evaluate the role of phloem anatomy in adapting grape cultivars to a wide range of different climates.Berry chemistry, anatomy and physiology were measured in summer 2020 for 18 grape cultivars established in an experimental vineyard on the University of California, Davis campus . There were 13 red-fruited and 5 white-fruited cultivars. Further, 9 cultivars were classified as hot-climate, 7 as warm-climate and 2 as temperate climate, using the definitions from Anderson & Nelgen . Anderson & Nelgen sorted the major wine-growing regions worldwide into climate categories based on mean temperature over the growing season . Cultivars were then placed into their respective climate category based upon the highest proportion of bearing area grown in a particular climate category as of 2020. This proportion of land area devoted to growing a particular cultivar worldwide was taken as a thermal requirement, genotypically driven, to match sugar accumulation with a region’s climate. Plants were growing as mature vines, grafted to the same rootstock , and trained to a bilateral, spur-pruned, vertical shoot-positioned trellising system with a North-South row orientation . Davis is considered a hot, dry site for wine growing, with campus weather stations reporting a decadal average mean annual precipitation of 436 mm and mean growing season temperature of 19.8°C . Our study period was exceptionally hot, with mean daily and mean maximum daily temperatures ranging from 22.8-24.5°C and 32.6-34.4°C, respectively, partly due to the anomalous August 16 – 18 heatwave . Over the study period, vines were drip-irrigated weekly at 50% replacement of vineyard evapotranspiration, which was estimated from the reference evapotranspiration reported by the campus weather status and published crop coefficients for this trellising system and vine × row spacing .Leaves and berries were sampled to measure petiole, midvein, and pedicel anatomy in the morning on three days at the end of the growing season . Two berries and leaves per vine were excised with a razor blade. Leaf position was standardized as the 6th leaf from the shoot apex, to capture the most photosynthetically active leaves. Two leaf and one berry sample per vine were then prepared for light microscopy, and the other berry sample was prepared for scanning electron microscopy. For light microscopy, a 1-cm segment of leaf petiole and lamina and the entire pedicel of the berry were immediately excised and placed into a vial of chilled Formalin-Acetic Acid . Vials were put on ice and refrigerated at 4°C for at least 24 hours before further processing. For scanning electron microscopy, pedicels were immediately flash-frozen and immersed in liquid nitrogen for 1-min and placed into a chilled micro-centrifuge tube of 100% ethanol, then the tube was immersed in liquid nitrogen until the ethanol congealed . Samples were then immediately placed on ice and stored in a -20°C freezer for at least 24 hours before further processing.After 7 days in FAA, the light microscopy samples were soaked in 50% ethanol for 5 mins and then stored in 70% ethanol in preparation for paraffin embedding. Samples were first infiltrated with paraffin by using an Autotechnicon Tissue Processor to treat samples with the following sequence of solutions: 70%, 85%, 95%, 100% ethanol, 1 ethanol:1 toluene, 100% toluene , and paraffin wax , each for 1 hour. The infiltrated samples were then embedded into paraffin blocks with a Leica Histo-Embedder , and allowed to cool. A rotary microtome was then used to make 7μm-thick cross-sections for leaf laminas, petioles, and berry pedicels. Pedicel cross-sections were sampled from the receptacle and petiole and midvein cross-sections were sampled near the interface of the lamina and petiole. After the cross-sections were imaged, pedicels for four cultivars were remelted from their wax molds, oriented longitudinally and sectioned again at 7μm to obtain sieve element lengths. Sections were stained using a 1% aniline blue and 1% safranin solution following a modified staining procedure . Sections were then viewed under bright field or florescence microscopy using a Leica DM4000B microscope and a DFC7000T digital camera .The pedicel electron microscopy samples were processed following Mullendore .

These practices include use of vegetative shoots to shade the fruit, using shade cloths to reduce berry radiative heating, spraying berries with a natural “sunscreen” such as a clay compound, water misting with sprinklers and, when slope permits, changing the row orientation to reduce or balance solar radiation exposure. Shade cloths, which are the focus of this work, reduce temperature by controlling the transmission of incoming radiation to the fruit zone,without completely blocking all incident radiation, which could lead to a reduction in grape quality and an increase in disease risk. Shade cloths can be used to cover the entire canopy and thus affect a large-scale change in vineyard microclimate, or they can be applied directly to the fruiting zone to localize their impacts to berry microclimate. Previous studies have reported that shade cloths are effective in reducing maximum berry temperatures, though they have used different methods for quantifying these effects. Mart´ınez-Luscher et al. ¨ reported that 40% black shade cloths covering the fruiting zone of the canopy reduced cluster temperature by 3.7◦C during the warmest time of the day, large round plant pots while Greer found that 70% shade cloths covering the grapevines reduced canopy temperature by an average of 4.6◦C throughout the day.

Similarly, thin shade cloths and plastic films covering the grapevines were shown by Rana et al. to reduce midday berry temperatures by 2◦C and 6◦C below air temperature, respectively. While it is clear that shade cloth can be effective in reducing overall berry temperature, a higher degree of control of berry temperature may be desired. In certain instances, it may be beneficial to reduce berry temperature by a defined margin to avoid negative trade-offs, while also balancing temperatures between opposing sides of the vine. However, many interacting variables are likely to influence the efficacy of shade cloth, such as row orientation, row spacing, trellis type, and topography. Due to the large number of important variables affecting berry temperature, it can be difficult to generalize the relatively small number of experimental results that are only able to explore a few variable combinations in order to predict the effect of shade cloth for a given vineyard system. Crop models provide the potential for generalizing the results of field experiments to predict the outcomes of proposed management strategies for a specific site or climate scenario. Such models could allow for optimization of the design or management of vineyards to mitigate elevated berry temperatures under current or future climates, given that a large number of simulations can be efficiently performed to cover a wide parameter space.

Previous work has developed models of spherical fruit temperature, including one study that simulated the effect of hail nets on apple temperature. In a recent study, a 3D model was developed and validated that accurately simulated the spatial and temporal temperature fluctuations of grape berries in vineyards with different climates, topographies, and trellises.However, the current version of this model is not able to represent the effects of shade cloth on canopy and berry temperature. The overall goal of this work was to enable model-based evaluation and optimization of strategies for grape berry temperature control using fruit zone shade cloth. With this goal in mind, specific objectives of this study were to: 1) develop a physically-based 3D model of grape berry temperature that incorporates the effect of shade cloth, 2) generate an experimental data set against which the model can be validated, and 3) quantify the interacting effects of different strategies for excessive berry temperature mitigation such as altered row orientation, row spacing, topography, and shade cloth density.The model of grape berry temperature was based on the 3D model described in Ponce de Leon´ and Bailey, and modified to include the effects of shade cloth. A brief description of the overall model is provided below, with a focus on novel additions associated with shade cloth. The model was developed within the Helios modeling framework and has been validated based on field measurements of berry temperature between veraison to harvest. The computational domain consists of 3D geometric elements that fully resolve the spatial structure of the plants, berries, and shade cloth .

The berries were represented by 3D tessellated spheres composed of triangular elements, the ground surface by a planar grid of rectangular elements, the woody tissues by a cylindrical mesh of triangular elements, and the leaves by planar rectangles masked to the shape of leaves using the transparency channel of a PNG image. The shade cloth was formed by rectangles masked to the shape of a grid using the transparency channel of a PNG image, where “holes” in the shade cloth were created based on a grid of transparent pixels.Radiation transfer was simulated using a backward-ray-tracing approach that ensures each geometric element is adequately sampled for both short-wave and long-wave radiation. The model launches a large number of rays from each geometric element to simulate the various modes of radiation transfer, including emission, reflection and transmission based on the radiative properties of each element. When a ray encounters a transparent pixel on an element masked by a PNG image, the ray continues with no interaction. This allows for an efficient fully-resolved representation of shade cloth with a large number of holes. To eliminate domain edge effects, periodic lateral boundaries can be enabled that effectively creates an infinitely repeating vine geometry in the horizontal. For berries, the latent flux term was assumed to be zero since latent cooling is typically considered negligible after veraison. For this study, heat released from metabolic activity ´ within the fruit was assumed to be low enough to be neglected. The heat transfer coefficient from fruit, ground, and leaf surfaces to the atmosphere, h, are specified as described in Ponce de Leon and Baile. Previous field tests suggested an important role of berry heat storage in accurately representing temperature dynamics, and laboratory and field tests have shown that the chosen values for Cp and rhoA result in berry dynamic temperature responses in close agreement with measurements.To evaluate the model accuracy, the time series of experimental measurements and simulated temperatures for berries furthest west were compared. Model agreement with field measurements was quantified using the error metrics normalized root mean squared error – normalized by the difference between maximum and minimum measured data, the coefficient of determination , plant pots round and the index of agreement. To analyze the modeled berry temperature results in the “simulation experiment”, we took the average temperature of five berries in each of five exterior clusters on both sides of the vine. For comparison purposes, the total canopy and cluster daily light interception was calculated by integrating the light interception fluxes over the day. The daily light interception was calculated per vine area for the canopy and per berry surface area for the clusters To compare the effect of shade cloth density on berry temperatures in the simulated vineyard designs, we used indices based on the duration of elevated temperature and the intensity . The 35◦C temperature threshold was chosen because it has been reported to correspond to the approximate onset of unfavorable effects of elevated temperature on grape composition. Furthermore, to identify conditions that effectively balance berry temperature between opposing sides of the vine, we constructed a conditional inference tree with the variables listed in Table 4.2. The conditional inference tree was constructed using the “party” package of R statistical software. The conditional inference tree is a tree-based classification algorithm that performs binary recursive partitioning of data into groups containing observations with similar values. Conditional inference trees are similar to decision trees, the main difference being that each node in the conditional inference trees uses a significance test of independence to select a predictor variable rather than selecting the predictor variable that maximizes the information measure. In the conditional inference tree, predictor variables are circled and ranked and the ones at the top have the highest correlation with the response variable.

The algorithm stops if the null hypothesis of independence is not rejected, however, for visualization purposes, the maximum depth of the decision tree was set to 4.The magnitude of the wind speed varied across the sampling period, but overall Unilateral tended to have greater wind speeds compared to Goblet . During the day, the wind in the fruiting zone tended to come from the east while at night the wind tended to come from the west for both trellis systems . Since the row orientation of Goblet and Unilateral was N-S and the vines were on an east-facing slope, the wind coming from the east tended to be of greater magnitude. For both Goblet and Unilateral, the relative humidity significantly decreased on 25 Sept. 2019, likely due to the increase in air temperature. Overall, during the sampling period, Unilateral tended to be slightly less humid compared to Goblet. This can be explained by the wider row spacing in Unilateral that enhanced mixing of the canopy air compared to Goblet .During the sampling period, average daily maximum temperatures of the west-facing berries under the shade cloths were 1.6◦C and 2.7◦C higher than the daily maximum air temperature in Goblet and Unilateral, respectively. The control west-facing berries with no shade cloth were up to 8.2◦C and 5.9◦C above the daily maximum air temperature in Goblet and Unilateral, respectively . The relative reduction in maximum berry temperatures due to the shade cloth in Goblet and Unilateral was consistent across the sampling period, which included a wide range of ambient air temperatures . Pulp temperatures of more than 40◦C were measured on 25 Sept. 2019 for unshaded berries in both trellis systems. For both Goblet and Unilateral, the berry temperature under the shade cloth was close to the air temperature in the morning, while air temperature differences between berries under the shade cloths increased in the afternoon. The peak in measured elevated temperatures happened at different times in Goblet and Unilateral , primarily due to the influence of the ratio between plant height and row spacing on berry exposure. In the evening, under low-light conditions, the berry temperatures were similar to the air temperatures, while at night, radiative cooling likely caused the pulp temperature to fall below the air temperatures. Under low light and at night, the temperature differences among treatments were small .The model was validated by using the experimental measurements to determine whether the modeled berry temperatures appropriately responded to the shade cloth relative to the control . The model reproduced the magnitude of the berry temperature increase over air temperature reasonably well for both Goblet and Unilateral. The largest source of error appeared to be due to the transition period when berry sun exposure began, where the time of the simulated maximum temperature increase tended to happen earlier than that of the measurement . This mismatch could be due to slight inaccuracies in determining the position of each berry and leaf.Figures 4.7, 4.8, and 4.6 summarize the results of the simulation experiment in which the effect of different row orientations, row spacing, and slope aspects on berry temperature were evaluated. Orienting vineyards N-S on a flat terrain allowed for uniform canopy and cluster exposure to solar radiation, since radiation is approximately symmetric about the N-S axis . However, the berry temperature on the west side of the vine significantly increased in the afternoon compared to the east side because hysteresis in air temperature causes asymmetry about solar noon. On average, berry temperature on the west side of the vines was greater than 35◦C for about 1-2.5 hours longer than the east side . Interestingly, although there was temporal asymmetry due to air temperature and temperature extremes, the net daily accumulation of berry growing degree hours was virtually identical between each side of the vine . On flat terrain, rows oriented NW-SE increased light interception and fruit overexposure in the afternoon and E-W reduced light interception and fruit overexposure in the afternoon . The high exposure to direct sunlight in NW-SE oriented rows resulted in simulated berry temperatures up to 7.8◦C higher on the SE side compared to the NW side . Compared to rows oriented NE-SW, rows oriented NW-SE had an additional 3 hours of canopy light interception above 200 W m−2 between 14:00 and 17:00 and berry temperatures greater than 35◦C for 2 additional hours .

In both 2020 and 2021, there were HWs that occurred mid to late August. Looking at anthocyanin concentration, there was more variation in concentrations among treatments in 2020. Additionally, concentrations were higher in 2021 among the three treatments. The higher anthocyanin concentrations may be due to less extreme HW temperatures, thus less anthocyanin degradation. Looking at Figure 5, in 2020, there were no significant differences between the treatments during HW2, but looking at HW3, the 60% ET treatment suffered the most significant losses. At the start of HW4 the 120% ET treatment had significantly higher flavonol concentrations than the 60% or the 180% treatments. Nevertheless, at harvest there were no significant differences between the three treatments. In 2021 as seen in Figure 5, there were no significant differences in flavonol concentration until HW2 where there were differences between the 60% and the 120% ET treatments. Interestingly, there was a major decline in concentration for the 120% ET treatment at the start of HW2, and by commercial harvest, plant plastic pots this treatment has the lowest concentration. This may be due to differences in light exposure because flavonols develop when exposed to light.

The 120% treatment may have had the lowest flavonol concentration at harvest because these vines had the most water applied during the growing season, so there was likely more foliage covering the berries. Similar to anthocyanin concentration, flavonol concentrations reached higher peaks in the 2021 growing season than in the 2020 growing season. Flavonol concentration went beyond 0.20 mg/B for the 60% ET treatment in 2021, but did not exceed 0.15 mg/B in 2020. This may be due to less extreme HW temperatures in 2021 and more direct sunlight exposure that allowed for increased flavonol development. As seen in Figure 6, the 2020 results show that, following HW2, there was a significant difference between the 60% and 120% treatments. This is also seen at the start HW3, and all treatments saw a marked decrease in PAs leading to no significance between them for the rest of the season until at harvest where there was a difference between the 60% and 180% treatments. Also seen in Figure 6, in 2021, there was a significant difference between the 90% and 120% ET treatments at the start of HW1 and at the start of HW2. After HW2, significant differences were seen between the 60% and the other two treatments. Overall, there were more significant differences between the treatments during the 2021 growing season compared to the 2020 growing season. In 2020, PA concentrations were on a similar trend among the three treatments. The larger variations in PA concentrations between treatments in 2021 may be attributed to the severity of the HWs and the impact it had on the grapevines.

During the 2021 growing season, the berries got sunburnt due to high exposure, and therefore more irrigation was applied in order to preserve quality. Table 1 shows the summary statistics of the RNA sequencing. Sample 1_NW_B3R2 was an outlier and removed from the analysis due to having a higher number of reads compared to the other samples. For each irrigation treatment, the berry transcriptomes of two consecutive dates of collection were compared to evaluate the number of differentially expressed genes . The purple represents the 60% ET treatment, the teal represents the 120% ET treatment, and the yellow represents the 180% ET treatment. As seen in the figure, there were significantly more genes differentially expressed between the HW vs. pre-HW dates than the HW and post-HW dates for the 60% ET and 120% ET treatments. Interestingly, it was the opposite for the 180% ET treatment. For each pairwise comparison of collection dates, the DEGs detected for the three irrigation treatments were compared . Looking at the top two diagrams, there is a larger number of shared genes unique to the 60% and the 120% treatments compared to those uniquely shared with the 180% treatment. Specifically, there were 550 up-regulated genes shared only between the 60% and 120% treatments versus the 96 and 38 genes only shared with the 180% treatment. Looking at the bottom two diagrams, there is an overall decrease in the number of genes being differentially expressed when comparing the post-HW date relative to the HW date. There is also a higher number of genes being differentially expressed for the 180% treatment with 478 being up-regulated and 605 being down-regulated. In terms of berry temperature, significant differences among the treatments were only observed on August 13th, which is the pre-HW date for the August 2020 HW. Measurements recorded throughout the remaining HW dates showed that berry temperature remained similar among the three treatments. These results may be due to the berries being in the shade. In a study done by Ponce de Leon and Bailey , they found that shaded berries tended to have similar temperatures to the ambient air temperature and could reach over 10 °C above ambient temperature when in direct sunlight. There is currently a lack of published literature that explores the effects of HWs and irrigation on berry temperature, and the results from this study suggest that the two factors do not play a significant role in berry temperature. There were major declines in anthocyanin concentration in 2020 and 2021 for the 60% ET treatment, which suggests a suppression of anthocyanin synthesis and promotion of degradation at such high temperatures. This finding remains consistent with published literature, such as the work done in Yan et al. . In their study, three experiments were conducted on Vitis vinifera L. cv. Merlot, cl. 347 in which the grapevines were exposed to three different temperature regimes.

Their results consistently showed that the low-temperature regimes and high-temperature regimes had the highest and lowest anthocyanin levels, respectively. Further evidence of anthocyanin synthesis suppression and promotion of degradation at high temperatures is found in Mori et al. . Similar to the experimental design in Yan et al. , Kyoho grape berries in this study were grown under different temperature conditions. Anthocyanin levels were consistently lower in berries grown under high temperature conditions compared to berries grown at 25 °C or berries grown at 30 °C during the day and 15 °C at night. These results were attributed to a decrease of UFGT activities in the flavonoid pathway, as previously mentioned. Particular attention should be given to the anthocyanin results seen in 2020 . By harvest, the 120% ET treatment was significantly different from the 60%, black plastic pots but not significantly different from the 180% treatment. This is important because similar results were seen in anthocyanin concentrations with much less water used for irrigation. These results further support research that has proven the beneficial aspects of deficit irrigation. As seen in Bucchetti et al. and Roby et al. , deficit irrigation consistently increased anthocyanin concentrations by reducing berry size and thus increasing content per berry. That being said, theresults from this study show that overwatering during HWs is unnecessary when trying to compensate for berry phenolics. In terms of flavonol concentration, particular attention should be given to the 120% ET treatment in the 2021 growing season . By harvest, there was a major decline in concentration for this treatment. As previously mentioned, flavonol synthesis is light-dependent, and shading can have notable effects on flavonol concentration . Since sunlight is a key influencing factor, the decline in flavonol concentration for the 120% ET treatment may be attributed to a denser canopy that provided more shading to the fruit, which inhibited flavonol synthesis. In the 2020 and 2021 growing seasons, total PA concentration was significantly lower in the 60% ET treatment than the other two treatments by harvest . Since HWs occurred in both seasons pre-veraison, the treatment differences likely happened during PA synthesis, which occurs from flowering to veraison. The pre-veraison HWs could have impacted PA synthesis in the 60% ET treatment, which was exposed to higher water and heat stress, thus decreasing PA concentration. Although studies have shown variable results on the effects of heat events on PA concentration, PAs are unlikely to degrade due to the high stability of their chemical structure . A common trend seen throughout both years is that the 180% and 120% treatments from 2020 and 2021 respectively resulted in lower phenolic concentrations than the 120% and 90% treatments. This is important to note because these results suggest that irrigation prior to HWs can be beneficial in maintaining fruit quality, but excessive watering may negate the beneficial aspects of deficit irrigation. In terms of the lower anthocyanin biosynthesis in the 3x and 2.5x treatments, it may be related to plant water status since moderate deficit irrigation has been shown to increase anthocyanin biosynthesis and promote ripening . Additionally, this may also be due to insufficient light exposure of the clusters since the canopies were more dense with foliage.

As seen in Figure 7 and Figure 8, there were significantly more genes differentially expressed between the HW vs. pre-HW dates than the HW and post-HW dates for the 60% ET and 120% ET treatments, and it was the opposite for the 180% ET treatment. This may potentially be a combined response to the heat stress and too much irrigation being applied. The RNA sequencing results showed that there were several down-regulated genes from the phenylpropanoid and flavonoid pathways shared between the pre-, during, and post-HW dates and irrigation treatments. What is potentially being observed is a general repression of core and peripheral phenylpropanoid pathways, which are normally triggered in red-skinned grape berries throughout ripening . Some of the genes that deserve particular attention include trans-cinnamate 4-monooxygenase , 4-coumarate-CoA ligase , chalcone synthase , flavonol synthase, F3’5’H, and UFGT. C4H and 4CL play key roles in the phenylpropanoid pathway. C4H catalyzes the reaction that forms p-coumaric acid, and 4CL converts p-coumaric acid to 4-Coumaroyl-CoA . The down-regulation of C4H and 4CL are important to note because 4-Coumaroyl-CoA is an important precursor for compounds produced in the flavonoid pathway, and decreased production of this precursor may lead to overall decreased levels of phenolic compounds. Chalcone synthase is the first key enzyme in the flavonoid pathway, and therefore plays a central role in initiating flavonoid biosynthesis . The down-regulation of this gene may lead to reduced flavonol levels in grape berries, which is crucial in times of excessive heat and light exposure due to their nature as UV protectants. Flavonol synthase plays an important role in converting dihydroflavonols to flavonols . F3’5’H catalyzes flavonoid hydroxylation, which leads to the formation of flavonols, anthocyanins, and PAs . UFGT converts anthocyanidins to anthocyanins . The down-regulation of these genes lead to decreased production of phenolic compounds, and such effects have been well-documented . Implementation of differential irrigation prior to and during HWs were shown to have a major impact on berry composition and gene expression. Damaging effects on berry quality were observed from underwatering and overwatering. Significant changes in berry composition occurred throughout the HWs, including a suppression of anthocyanin synthesis and promotion of degradation, and lower flavonol and PA concentrations in highly irrigated treatments. The down-regulation of key enzymes involved in the phenylpropanoid and flavonoid pathways, suggest a possible mechanism for the lower phenolic concentrations. The frequency and duration of extreme heat events predicted for the upcoming decades indicates the need for further field research looking at potential strategies to mitigate the negative effects of heat waves on berry composition and gene expression. Misting, shade cloths, cover crops, canopy management, and trellis systems that protect fruit exposure remain as options to help cope with the effects. Furthermore, studying acclimation within and across seasons of different cultivars to extreme heat events will help guide the grape and wine industry towards cultivars with better adaptations and ultimately higher quality fruit and wine. Obesity has become a major health problem worldwide and in the absence of an effective universal medical approach to tackle this epidemic, many patients use over-the-counter weight loss supplements to help them lose weight. Numerous products are available that promote weight loss and appetite suppression and are sold as fat burners. These supplements are often sold without any regulatory process or having undergone any Food and Drug Administration approved clinical trial showing safety and efficacy.

While used traditionally in a number of cultures, one of the best examples of its medicinal use is from the Kuna Indians who have lived for centuries on remote islands off of the Caribbean coast of Panama. This group of indigenous people is famous the lack of hypertension, an infrequent prevalence of CVD, diabetes, and cancer, and a longer lifespan, compared to Panamanians living on the mainland. However, when these people migrate to an urban environment, the incidence of hypertension and vascular diseases increased significantly. Nutritional assessments showed that the consumption of total fruit, fish, and cocoa-containing beverages were significantly higher among Kuna Indians living on the island compared to those residing in Panama City, even though the overall dietary intake of added sugars and salt was higher in the indigenous group. Scientists hypothesized that cocoa may be an influencing factor in the low prevalence of CVD in this population, due to its high concentration of flavonoids. The primary flavonoids in cocoa are flavanols, including monomeric catechins, epicatechin, and polymeric procyanidins. Cocoa also contains methylxanthines, i.e., theobromine and caffeine, large plastic growing pots which remain in flavanol-poor cocoa butter and cocoa solids after pressing. The effect of cocoa flavanols on vascular function was first reported more than two decades ago.

Extending the observations about cocoa flavanols to broader dietary patters, studies exploring the association between the intake of flavonoids and the risk of CVD have yielded inconsistent results, suggesting that certain sub-classes may be more effective than others in terms of cardio-protection. Some observational studies have shown that the dietary intake of flavanols was associated with a decreased risk of CVD and ischemic heart diseases. Epidemiological studies have reported that a moderate amount of chocolate consumption was associated with a decreased risk of CVD. A Cochrane meta-analysis concluded that the consumption of flavanol-rich chocolate and cocoa products had a small but statistically significant effect on reducing systolic and diastolic blood pressure, both by 1.76 mmHg. Similarly, another systematic review and meta-analysis included 42 acute and short- term randomized controlled trials concluded that chocolate, cocoa, and flavanol intake significantly improved vasodilation function as measured by flow-mediated dilatation , reduced diastolic blood pressure by 1.6 mmHg, and marginally improved the serum cholesterol profile. However, these results were strongest among individuals with moderately elevated blood pressure and untreated hypertension. The vasodilation function in healthy males, measured by FMD, was significantly increased one to four hours after taking a cocoa drink containing 917 mg of cocoa flavanols, compared to baseline values and to those consuming a control beverage with 37 mg of flavanols. 

The pattern of improvement in FMD from the flavanol-rich cocoa beverage was closely mirrored when participants also consumed 1 or 2 mg/kg of body weight of -epicatechin dissolved in water, suggesting -epicatechin and its metabolites were the main contributors of the vascular effects. Additional research from the same study found that while -epicatechin is a primary contributor to the vasodilation function, dimeric and oligomeric procyanidins that are metabolized by the gut microbiome may also contribute to the vasculo-protection. In healthy young men, daily intake of a cocoa extract containing 130 mg of -epicatechin and 560 mg of procyanidins for 30 days significantly improved FMD and reduced blood pressure and arterial stiffness as measured by pulse wave velocity , while 20 mg of -epicatechin and 540 mg procyanidins, or a control capsule, did not. However, total cholesterol was decreased after in both groups consuming cocoa, suggesting synergistic effects of -epicatechin and procyanidins, possibly through gut microbiome-mediated catabolism. Cocoa also contains methylxanthines, which are biologically active. While the intake of theobromine and caffeine alone did not result in a significant change in vascular endothelial function measures, interestingly, the combination of methylxanthines plus a high cocoa flavanol drink induced a significant improvement in FMD response than the beverage only. In addition, plasma metabolites of -epicatechin were higher after consuming the flavanol-rich cocoa drink with methylxanthines than when the flavanols were consumed alone, indicating a likely interaction between theobromine, caffeine, and cocoa flavanols on vascular function. Several molecular mechanisms regarding the effects of flavanols on blood pressure and vasodilation have been proposed. Flavanols such as -epicatechin can increase nitric oxide production directly by increasing endothelial nitric oxide synthase expression. The release of NO consequently increases intracellular cGMP which then induces a relaxation of vascular smooth muscle cells. The increased eNOS activation may also be modulated by flavanols through a calcium/calmodulin pathway by increasing the intracellular calcium concentration, or by phosphatidylinositol 3-kinase/protein kinase B -dependent eNOS phosphorylation. In addition, -epicatechin has been shown to down-regulate the expression of nicotinamide adenine dinucleotide phosphate oxidase by inhibiting the synthesis of vasoconstrictors such as endothelin-1, and therefore increase the utilization of NO.

Flavanols may also directly inhibit angiotensin-converting enzyme activity, which increases NO production. Apart from modulating NO production, flavanols may also induce the release of endothelium-derived relaxing factors such as hydrogen peroxide and prostacyclin. Cocoa flavanols also benefit cardiovascular health by inhibiting platelet activation and adhesion. In healthy individuals, platelet aggregation induced by collagen and adenosine diphosphate, and the expression of P-selectin, was significantly decreased compared to a placebo group after the daily intake of 234 mg of cocoa flavanols and procyanidins for 28 days. Some studies have reported that the reduction in platelet aggregation was not different between flavanol-rich darkchocolate or low-flavanol dark chocolate mixed with white chocolate, suggesting potential antiadhesive effects from methylxanthines. While the exact mechanisms to explain the interaction between flavanols and platelets are still under investigation, proposed mechanisms from in vitro and ex vivo models include an inhibition in the expression of endothelial adhesion molecules , and the down-regulation of pro-inflammatory factors such as interleukin -6 and tumor necrosis factor-α, large plastic pots which also decrease the recruitment of other proinflammatory compounds. Mango originated from the Indian subcontinent and has been cultivated for thousands of years. The bark, leaves, roots, and flowers of the tree, and the peel, kernel, and pulp of the fruit, have been used in traditional medicine in tropical and sub-tropical regions throughout the world. The bark and leaves have been used for treating diarrhea and diabetes in Bangladesh, and Ghana, with the pulp and kernel used for hemorrhaging in the lungs and intestines in India.54 Mango fruit is a rich source of fiber, vitamins C and E, folate, potassium, β-carotene, and phenolic compounds. Dietary intake of vitamins C and E, and β-carotene, are associated with reduced risks for CVD. Major phenolic compounds reported in mango pulp include mangiferin, quercetin, kaempferol, myricetin, catechin, gallic acid, ferulic acid, protocatechuic acid, and chlorogenic acid. One study observed that a higher mango intake was associated with improved nutrient intakes, diet quality, and body mass index , factors known to reduce the risk of CVD. Clinical trials also suggest that mango fruit may have protective effects against the development of CVD. Daily intake of 200g of fresh-cut Ataulfo mango for 30 days decreased blood lipids and increased the plasma antioxidant capacity in healthy adults. In obese men and women aged 20-50 years, supplementation of 10 g/d freeze-dried mango pulp for 12 weeks decreased blood glucose levels but not inflammatory or any cholesterol markers. Another study reported that the daily intake of 400 g of fresh frozen mango pulp significantly decreased systolic blood pressure only in individuals with a BMI of 18-26.2 kg/m2 . In contrast, plasminogen activator inhibitor 1, IL-8, and mitochondrial pyruvate carrier-1 were significantly reduced in individuals when the BMI was partitioned as > 28.9 kg/m2 . In addition, in participants with impaired glucose sensitivity, the supplementation of 100 or 300 mg/d of mango fruit powder with 250 ml water daily for four weeks significantly increased the vasodilation of arteries as measured by the reactive hyperemia index compared to a placebo group.

Mangiferin is a unique compound in mango that has been studied for its vasculo protective effects . A mango bark extract with a high concentration of mangiferin decreased cholesterol in plasma and liver, and reduced oxidative stress in mice. A subsequent human study showed that the daily intake of 900 mg of Vimang® for 90 days reduced a measure of serum oxidative stress compared to a control group among older individuals. In both the animal and human studies, the marker of oxidative stress, while considered valid at the time of the study, is now viewed with limitations. In overweight hyperlipidemic individuals, the daily intake of 150 mg of mangiferin for 12 weeks significantly improved lipid profiles and glucose homeostasis. In hyperuricemic rats, mangiferin intake significantly reduced SBP, serum uric acid and inflammatory markers, and increased the expression of eNOS. One potential mechanism to help explain the vasodilatory effect of mangiferin may be due to the increased expression of eNOS, and therefore enhanced the production of NO. Reports have shown that the composition of phenolic compounds in mango varied significantly among different varieties. Mango varieties with high polyphenol content, such as Ataulfo, may play a more prominent role in cardiovascular health, but the interaction between the polyphenols, carotenoids and other bio-active compounds in mango must be considered. Further studies may also focus on the potential effects of mango by-products on metabolic health, since the total concentration of phenolic compounds is higher in the kernel, peel, leaves, and bark compared to the edible fruit. Such explorations may be useful in processing what is considered as agricultural waste into useful extracts. Low-bush blueberry and high-bush blueberry are two common species originally grown in North America. Native Americans have a long folklore history of using both types of blueberry plants to treat rheumatism and infection. Anthocyanins are responsible for the red, blue, and purple color in ripe berries. Blueberries are one of the most abundant sources of anthocyanins in commonly consumed fruits. The total anthocyanin level in fresh blueberries is significant, reaching up to 487 mg/100g. Blueberries also contain appreciable amounts of proanthocyanidins and hydroxycinnamic acids , along with vitamins and minerals, fiber, and small quantities of flavonols and flavanols. Epidemiological studies suggest that a higher dietary anthocyanin intake is associated with a lower risk of hypertension, and reduced arterial stiffness in women, though these studies do not specify blueberries as the sole source of these bio-actives. A meta-analysis of 19 cohort studies reported that the dietary intake of anthocyanins was associated with a decreased risk of coronary heart disease and CVD mortality, but not myocardial infarction, stroke, or total CVD risk. The effects of blueberries on markers of CVD risk have been studied. In obese postmenopausal women with pre- and stage I-hypertension, daily consumption of 22 g of freeze-dried blueberry powder containing 469 mg of anthocyanins for eight weeks significantly reduced systolic and diastolic blood pressure by 7 mmHg and 5 mmHg, respectively, and arterial stiffness measured by brachial-ankle PWV, compared to their baseline values or to a placebo group. In healthy males, FMD was significantly increased one, two, and six hours after the intake of 34, 57, and 80 g of blueberry powder mixed in water , compared to a control drink. However, no changes were seen in arterial stiffness measures. In addition, the increase in polyphenol metabolites and decrease in neutrophil NADPH oxidase in plasma were correlated to FMD, suggesting that the phenolic metabolites after blueberry powder consumption effectively improved vasodilation functions by elevating the bio-availability of NO through inhibition of NADPH oxidase. Later the research group identified that the FMD improvements were mainly due to anthocyanin metabolites. The blood pressures of overweight and obese smokers who consumed 250 g of blueberries for three weeks showed no significant changes from baseline values . Among mid-aged women who were at risk for type II diabetes, daily consumption of 240 ml of wild blueberry juice with 314 mg of anthocyanins for seven days significantly improved serum nitrates and nitrites, but no change were noted for in glucose metabolism parameters, cholesterols, inflammatory markers, platelet adhesion molecules, vasodilation, or blood pressure, compared to baseline and the placebo group. Taken together, the above results suggest that clinical trials with blueberries may need require a few weeks or longer of regular intake in order to observe clinically significant changes. Similar to blueberries, the American-cranberry is also a plant that is native to North America and has a long history of botanical uses by indigenous people, such as for urinary tract disorders and diarrhea.

Sugars were measured at 25% using a Refractometer PAL-1 . The C content of sugar was calculated at 42% using the formula of sucrose. Below ground biomass was measured by pneumatically excavating the root system with compressed air applied at 0.7 Mpa for three of the 12 sampling blocks, exposing two vines each in 8 m3 pits. The soil was prewetted prior to excavation to facilitate removal and minimize root damage. A root restricting duripan, common in this soil, provided an effective rooting depth of about 40 cm at this site with only 5–10 fine and small roots able to penetrate below this depth in each plot. Roots were washed, cut into smaller segments and separated into four size classes , oven-dried at 60 °C for 48 h and weighed. Larger roots were left in the oven for 4 days. Stumps were considered part of the root system for this analysis.In vineyard ecosystems, annual C is represented by fruit, leaves and canes, and is either removed from the system and/or incorporated into the soil C pools, square pots for plants which was not considered further. Structures whose tissues remain in the plant were considered perennial C.

Woody biomass volumes were measured and used for perennial C estimates. Cordon and trunk diameters were measured using a digital caliper at four locations per piece and averaged, and lengths were measured with a calibrated tape. Sixty vines were used for the analysis; twelve vines were omitted due to missing values in one or more vine fractions. All statistical estimates were conducted in R.An earth moving machine was used to uproot vines and gather them together to form mounds. Twenty-six mounds consisting of trunks plus cordons and canes were measured across this vineyard block . The mounds represented comparable spatial footprints within the vineyard area . Mound C stocks were estimated using their biomass contribution areas, physical size, density and either a semi-ovoid or hemispherical model.The present study provides results for an assessment of vineyard biomass that is comparable with data from previous studies, as well as estimates of below ground biomass that are more precise than previous reports. While most studies on C sequestration in vineyards have focused on soil C, some have quantified above ground biomass and C stocks. For example, a study of grapevines in California found net primary productivity values between 5.5 and 11 Mg C ha−1 —figures that are comparable to our mean estimate of 12.4 Mg C ha−1 . For pruned biomass, our estimate of 1.1 Mg C ha−1 were comparable to two assessments that estimated 2.5 Mg of pruned biomass ha−1 for both almonds and vineyards. Researchers reported that mature orchard crops in California allocated, on average, one third of their NPP to harvestable biomass, and mature vines allocated 35–50% of that year’s production to grape clusters.

Our estimate of 50% of annual biomass C allocated to harvested clusters represent the fraction of the structures grown during the season . Furthermore, if woody annual increments were considered this proportion would be even lower. Likewise the observed 1.7 Mg ha−1 in fruit represents ~14% of total biomass , which is within 10% of other studies in the region at similar vine densities. More importantly, this study reports the fraction of C that could be recovered from winemaking and returned to the soil for potential long term storage. However, this study is restricted to the agronomic and environmental conditions of the site, and the methodology would require validation and potential adjustment in other locations and conditions. Few studies have conducted a thorough evaluation of belowground vine biomass in vineyards, although Elderfield did estimate that fine roots contributed 20–30% of total NPP and that C was responsible for 45% of that dry matter. More recently, Brunori et al. studied the capability of grapevines to efficiently store C throughout the growing season and found that root systems contributed to between 9 and 26% of the total vine C fixation in a model Vitis vinifera sativa L. cv Merlot/berlandieri rupestris vineyard. The results of our study provide a utilitarian analysis of C storage in mature wine grape vines, including above and below ground fractions and annual vs. perennial allocations. Such information constitutes the basic unit of measurement from which one can then estimate the contribution of wine grapes to C budgets at multiple scales— fruit, plant or vineyard level—and by region, sector, or in mixed crop analyses. Our study builds on earlier research that focused on the basic physiology, development and allocation of biomass in vines.

Previous research has also examined vineyard-level carbon at the landscape level with coarser estimates of the absolute C storage capacity of vines of different ages, as well as the relative contribution of vines and woody biomass in natural vegetation in mixed vineyard-wildland landscapes. The combination of findings from those studies, together with the more precise and complete carbon-by-vine structure assessment provided here, mean that managers now have access to methods and analytical tools that allow precise and detailed C estimates from the individual vine to whole-farm scales. As carbon accounting in vineyard landscapes becomes more sophisticated, widespread and economically relevant, such vineyard-level analyses will become increasingly important for informing management decisions. The greater vine-level measuring precision that this study affords should also translate into improved scaled-up C assessments . In California alone, for example, there are more than 230,000 ha are planted in vines. Given that for many, if not most of those hectares, the exact number of individual vines is known, it is easy to see how improvements in vine-level measuring accuracy can have benefits from the individual farmer to the entire sector. Previous efforts to develop rough allometric woody biomass equations for vines notwithstanding, there is still a need to improve our precision in estimating of how biomass changes with different parameters. Because the present analysis was conducted for 15 year old Cabernet vines, there is now a need for calibrating how vine C varies with age, varietal and training system. There is also uncertainty around the influence of grafting onto rootstock on C accumulation in vines. As mentioned in the methods, the vines in this study were not grafted—an artifact of the root-limiting duripan approximately 50 cm below the soil surface. The site’s location on the flat, valley bottom of a river floodplain also means that its topography, while typical of other vineyard sites per se, created conditions that limit soil depth, drainage and decomposition. As such, the physical conditions examined here may differ significantly from more hilly regions in California, such as Sonoma and Mendocino counties. Similarly, the lack of a surrounding natural vegetation buffer at this site compared to other vineyards may mean that the ecological conditions of the soil communities may or may not have been broadly typical of those found in other vineyard sites. Thus, to the extent that future studies can document the degree to which such parameters influence C accumulation in vines or across sites, large square plant pots they will improve the accuracy and utility of C estimation methods and enable viticulturists to be among the first sectors in agriculture for which accurate C accounting is an industry wide possibility. The current study was also designed to complement a growing body of research focusing on soil-vine interactions . Woody carbon reserves and sugar accumulation play a supportive role in grape quality, the main determinant of crop value in wine grapes. The extent to which biomass production, especially in below ground reservoirs, relates to soil carbon is of immediate interest for those focused on nutrient cycling, plant health and fruit production, as well as for those concerned with C storage. The soil-vine interface may also be the area where management techniques can have the highest impact on C stocks and harvest potential. We expect the below ground estimates of root biomass and C provided here will be helpful in this regard and for developing a more thorough understanding of below ground C stores at the landscape level. For example, Williams et al.estimated this component to be the largest reservoir of C in the vineyard landscape they examined, but they did not include root biomass in their calculations. Others have assumed root systems to be ~30% of vine biomass based on the reported biomass values for roots, trunk, and cordons . With the contribution of this study, the magnitude of the below ground reservoir can now be updated.California’s Mediterranean climate, albeit highly variable with frequent periods of drought and floods, provided the foundation for a diverse and vibrant agricultural industry to grow in response to the availability of low-cost labor and water supplies. Starting in the middle of the 19th century field crops–grains, forages, and cotton–dominated California crop landscapes, if not value of production, for a hundred years.

Toward the beginning of the 20th century, though, California agriculture began its move toward intensive cropping of vegetables and fruits. Railroads helped expand produce markets and low-wage immigrant labor. Later, migrants from the Dust Bowl, and then from Mexico, kept labor costs on fruit and vegetable farms competitive . Importantly, irrigation infrastructure and regulation—particularly water pumping, storage, transport, and rules of use—allowed cultivation of water-intensive summer crops where no rain fell for 6 mo each year. The Great Depression catalyzed massive surface water infrastructure developments such as the Colorado River Project and, in the late 1930s, the Central Valley Project by the US Bureau of Reclamation . Further growth of infrastructure in the postwar era included the State Water Project serving mostly cities and some agricultural lands in central and southern California. Infrastructure development over this period created one of the largest and most engineered irrigated agricultural systems in the world. The water supply network bridged the gap of hundreds of kilometers between the water-rich north—with mountains and heavy precipitation in the winter—and the low-precipitation Mediterranean climate central and south that plays host to most of California agriculture production and population. For nearly two centuries California farms have prospered through technological adoption, innovation investments, and on-farm management improvements. Yet with a changing climate coupled with increased concerns over the environment and sustainability, the landscape of California agriculture is changing. Over the past two decades, noticeably less land and water has been devoted to extensive field crops, as farms shifted to vegetables and tree and vine crops. These specialty crops generally produce higher revenues per unit of land and water . Expectations of higher returns have contributed to more than half of the state’s irrigated agricultural croplands growing fruits, nuts, and vegetables, which comprise roughly 80% of the farm revenue and employment . The degree to which these changes and concerns significantly reduce agriculture’s presence and productivity will depend on how Californians, including its growers and policymakers, respond.The mosaic of agriculture in California is driven by a variety of natural and human-created conditions . California’s terrain, climate, and soil heterogeneity are instrumental to California’s diverse array of agricultural commodities. The irrigated crop footprint alone is nearly 3.8 million hectares . Land in farms spans more than 10 million ha, producing over 400 crop and livestock commodities that annually generate around $50 billion in cash receipts and support 420,000 jobs in 2021 . The food and beverage processing sector, which primarily relies on local crop and animal supplies, supports an additional 250,000 jobs. Agriculture contributes significant shares of the income and employment in areas such as the CV, where labor, capital, irrigation water, management, and downstream sectors in livestock and food processing are closely linked. We briefly describe agriculture in three regions comprising the largest areas of irrigated acreage and commodity value: the CV, the Southern California Region, and the Coastal California. Agriculture in California’s foothills and mountain areas provide nearly 5 million ha of pasture and hay for cattle, along with the winter snow pack that historically stores nearly a third of California’s runoff that supplies CV irrigation as well as urban water use. CV. The nearly 52,000 km2 CV accounts for more than two thirds of California’s irrigated agriculture, encompassing a few major cities and dozens of moderate-sized rural communities. The northern part of the CV contains the Sacramento Valley and the Sacramento River basin, which averages 890 mm/y. of precipitation and is close to the snow pack-heavy northern mountains.

Our data showed that the expression of flavonoids/PAs related-genes was highly increased in V9-berries at the third harvest time compared to V7- berries, resulting in the accumulation of more PAs in V9-berries.Developing and producing table grapes with high quality is of utmost importance for the success of grapevine breeding programs. Scarlet Royal table grape , variety , is one such success story, producing premium fruit quality and becoming one of the major red varieties in California. However, under certain unknown circumstances, the berry quality of Scarlet Royal grapes can be affected by undesirable astringent taste, which can negatively impact marketability and consumer acceptance. Research on the relationship between astringency and phenolic composition in table grapes is still scarce, especially on the transcriptomic level. In this study, we aimed to understand the molecular events involved in the development of berry astringency, which is a complex set of sensations resulting from the shrinking, drying, drawing, or puckering of the mouth epithelium . We focused on Scarlet Royal berries from two different vineyards with contrasting astringency and analyzed the changes in phenolic-related compounds at six different time points from veraison until the last harvesting time.

Our panel test revealed that the V9-berries were perceived as more astringent, blueberry packaging a characteristic that could be attributed to their elevated levels of tannins . Differences observed between the two vineyards under study indicate that V7 vines yield more compared to V9. This difference may be attributed to the lower cluster count in V9, a factor known to potentially contribute to astringency, as suggested by Cañon et al., 2014 in wine grapes. Additionally, petiole analysis revealed higher levels of nitrogen and potassium in V9 vines compared to V7. Vine nutrient levels contribute to the final berry quality at harvest . These factors may also contribute to the higher levels of tannins detected in V9 berries; however, further research is needed to confirm this theory. Nevertheless, the two vineyards are located in close proximity to each other, and weather data collected from the same station in the Delano area indicates similar conditions. Therefore, it is unlikely that astringency or higher phenolic compounds are induced by weather factors. In fact, several studies, mainly in wine, have pointed to PAs as a determining factor for astringency intensity . For example, Vidal et al. reported that the total amount of tannins is the most plausible factor for sensory astringency, with flavan-3-ols dimers, trimers, and non-galloylated tetramers contributing to the astringency sensation. The PAs are a group of oligomers and polymers of flavan-3-ols and are the naturally occurring and predominant type of tannins in grapes and wine . Another study on aronia berry juice confirmed PAs as the key astringent compounds using sensory evaluation and phenolic profile approaches along with in-vitro models .

The study found that PAs with higher degrees of polymerization were responsible for the strong astringent mouthfeel . The composition of phenolic substances, especially PAs, seems to play a crucial role in determining berry astringency, and further exploration of this relationship is warranted in fresh fruits of different species and cultivars. Understanding the molecular basis of astringency development in Scarlet Royal berries can provide valuable insights for improving grape breeding programs and enhancing the overall quality of table grapes.The relationship between astringency and the berry polyphenols content has not been explored yet in table grape at the molecular level. To the best of our knowledge, the present study provides the first transcriptome profiling along with the changes of polyphenols in grape berries of the same variety but having astringency diversity . The transcriptome profile of both V7-berries and V9-berries underlined the remarkable transcriptional shift during berry ripening at different vineyards . Commonly, berry transcriptome profiles may widely vary based on many factors, including genotypic variations among varieties/species and developmental stages , as well as environmental circumstances. In our case of study, stemmed differences from the developmental stages and genotypic variations were eliminated, and hence the difference of the vineyard locations was the main source of variance with 97% of variance . The identified DEGs output of V9-berries compared to V7-berries is highly explanatory, including polyphenolic-related genes that are robustly expressed and co-regulated with astringency development, particularly in the V9-berries. The enrichment of the up-regulated genes with BP GO terms related to the biosynthesis of secondary metabolites, phenylpropanoid, and nitrogen compound metabolic process , commensurate with the higher amounts of N found in V9- berries . In fact, not only the levels of N fertilization but also its different forms highly affected the composition of phenolic compounds in leaves and wine . However, the synergistic/antagonistic effects of other macro- and micro-nutrients should also be considered. Our results highlighted the negative impact of above-normal amounts of macro-nutrients, mainly N, and to a lesser extent P and K, on the desirable attributes of grape berries.

Otherwise, the positive effect of Ca, Mg, and Mn were achieved as their levels were maintained within the normal range . These data should be also seen in the light of the highly enriched BP GO terms in the down regulated genes . Particularly, those for hormonal signaling pathways such as auxin, abscisic acid, strigolactones, as well as the KEGG pathway for the carotenoid biosynthetic pathway .The transcriptome profiling identified the common and unique molecular events featuring the development of tannins/astringency in grape berries. It is well-documented that the synthesis of PAs in grapevines is achieved via three sequential pathways: the shikimate pathway, the phenylpropanoid pathway, and ultimately the flavonoid pathway . Our results revealed that the expression levels of flavonoids/PAs-related genes were highly induced in V9- berries at the third harvesting time compared to V7-berries. The 19 selected genes were involved in the three pathways: the shikimate pathway, phenylpropanoids pathway, and flavonoids pathway. The shikimate pathway is an alternative route to produce aromatic compounds, including phenylalanine, tyrosine, and tryptophan, which serve as precursors for various metabolites, such as phenolic compounds . The up-regulation of genes like chorismate synthase and chorismate mutase in V9-berries may lead to the accumulation of phenylalanine, which is a critical precursor for the phenylpropanoid pathway. The latter pathway is responsible for synthesizing several end products, including PAs, anthocyanins, lignin, lignans, hydroxycinnamic acid esters, and hydroxycinnamic acid amides . Under the conditions of the V9 vineyard, several PAs/flavonoids structural genes such as PAL, C4H, 4CL, CHS, CHI, F3H, LDOX, LAR, and ANR were induced in V9-berries, leading to the accumulation of PAs in the berries . This process is facilitated by GSTs and transported by multidrug and toxic compound extrusion transporters. The activation of the PAs biosynthetic pathway in V9- berries may lead to a reduction in the necessary substrates for anthocyanin synthesis, resulting in low red color intensity in V9- berries compared to V7-berries. Additionally, the accumulation of PAs is associated with the development of astringency taste in V9-berries. Our study provides valuable insights into the molecular events underlying astringency development in Scarlet Royal berries. By integrating transcriptome profiling with polyphenolic composition analysis, the research shed light on the co-regulation of genes involved in the shikimate, phenylpropanoid, and flavonoid pathways, leading to the synthesis of PAs and ultimately influencing astringency. The findings from this research have implications for grapevine breeding programs and the production of high-quality table grapes. Understanding the molecular mechanisms underlying astringency development can help breeders in selecting and developing grape varieties with desirable attributes. Additionally, the knowledge gained from this study can inform vineyard management practices, such as nutrient fertilization, to optimize polyphenolic composition and berry quality. In conclusion, the data presented in this study indicates that berry astringency is strongly correlated with a high tannin content, blueberry packaging box likely resulting from the activation of nineteen genes within the phenylpropanoid pathway. The activation of these genes shifts the flavonoid biosynthesis pathway towards proanthocyanins, leading to increased tannin accumulation in the berries. It appears that triggering these events is associated with nutritional imbalances and a lower number of clusters per vine, as confirmed by petiole nutrient levels and the observed lower berry soluble solids and higher titratable acidity levels. The identification of these genes holds significant value for table grape genetic improvement programs. The nutrient imbalance theory derived from this research could be applied worldwide to optimize grapevine fertilization programs. Furthermore, it paves the way for further research in this area, with a particular focus on vine nutrients, crop load management, and berry astringency, thereby contributing to advancements in the field of table grape cultivation.The cultivated garden strawberry , an allo-octoploid , has a unique natural and domestication history, originating as an interspecific hybrid between wild octoploid progenitor species approximately 300 years before present1 . The genomes of the progenitor species, Fragaria virginiana and Fragaria chiloensis, are the products of polyploid evolution: they were formed by the fusion of and interactions among genomes from four diploid progenitor species approximately 1 million years before present.

Whereas two of the diploid progenitor species have been identified, the other two diploid progenitor species have remained unknown. Moreover, the history of events leading to the formation of the octoploid lineage and the evolutionary dynamics among the four sub-genomes that restabilized cellular processes after ‘genomic shock’ in allopolyploids remain poorly understood. Here, we present what is, to our knowledge, the first chromosome-scale assembly of an octoploid strawberry genome, the identities of the extant diploid progenitor species of each sub-genome, and novel insights into the collective evolutionary processes involved in establishing a dominant sub-genome in this highly polyploid species. The Rosaceae are a large eudicot family including a rich diversity of crops with major economic importance worldwide, such as nuts , ornamentals , pome fruits , stone fruits , and berries. Strawberries are prized by consumers, largely because of their complex array of flavors and aromas. The genus Fragaria was named by the botanist Carl Linnaeus, on the basis of the Latin word ‘fragrans’, meaning ‘sweet scented’, describing its striking, highly aromatic fruit . A total of 22 wild species of Fragaria have been described, ranging from diploid to decaploid. The genus Fragaria is highly interfertile between and within ploidy levels, thus leading to the natural formation of higher-polyploid species. Polyploid events, also known as whole-genome duplications, have been an important recurrent process throughout the evolutionary history of eukaryotes and have probably contributed to novel and varied phenotypes. Polyploids are grouped into two main categories: autopolyploids and allopolyploids, involving either a single or multiple diploid progenitor species, respectively. Many crop species are allopolyploids, thus contributing to the emergence of important agronomic traits such as spinnable fibers in cotton, diversified morphotypes in Brassica, and varied aroma and flavor profiles in strawberry. Allopolyploids face the challenge of organizing distinct parental sub-genomes—each with a unique genetic and epigenetic makeup shaped by independent evolutionary histories—residing within a single nucleus. Previous studies have proposed, as part of the ‘sub-genome dominance’ hypothesis, that the establishment of a single dominant sub-genome may resolve various genetic conflicts in allopolyploids. However, understanding of the underlying mechanisms and ultimate consequences of sub-genome dominance remains largely incomplete. sub-genome-level analyses in most allopolyploid systems are greatly hindered by the inability to confidently assign parental gene copies to each sub-genome, owing to both large-scale chromosomal changes and homoeologous exchanges that shuffle and replace homoeologs among parental chromosomes. Octoploid strawberry still has a complete set of homoeologous chromosomes from all four parental sub-genomes, thus greatly simplifying homoeolog assignment. Furthermore, gene sequences from extant relatives of the diploid progenitor species, which probably still exist for octoploid strawberry, can be used to accurately assign homoeologs to each parental sub-genome. However, a highquality reference genome for the octoploid is needed to fully exploit strawberry as a model system for studying allopolyploidy as well as to provide a platform for identifying biologically and agriculturally important genes and applying genomic-enabled breeding approaches. The assembly of the octoploid strawberry genome, with an estimated genome size of 813.4 Mb, has been particularly challenging because of its high heterozygosity and ploidy level. For example, the most recently published version of the octoploid strawberry genome is highly fragmented, with more than 625,000 scaffolds, and largely incomplete, with less than 660 Mb assembled after removal of the numerous gaps. Thus, that version of the genome, owing to its overall highly fragmented nature, has not been a useful resource for genome-wide analyses including the discovery of molecular markers for breeding.Our goal was to obtain a high-quality reference genome for the Fragaria×ananassa cultivar ‘Camarosa’, one of the most historically important and widely grown strawberry cultivars worldwide.

Farms in our sample had an average of $1.4 million in assets and $0.6 million in debts. The average debt-to asset ratio was close to 0.5. This ratio is much higher than the 0.16 debt-to-asset ratio reported by the United States Department of Agriculture for all American agriculture in 2003. When viewing assets and debts as financial inputs necessary to generate revenue, the ratio of financial input to gross sales was highest for vegetables and lowest for orchard crops.This study provides a detailed statistical profile of an important segment of California agriculture, the horticultural crop industry. The information provided is based on a unique survey of growers of horticultural crops, also known as specialty crops, that was conducted during the spring of 2002 at the request of the Risk Management Agency of the United States Department of Agriculture . This report presents data about horticultural industries in California and about the risk management attitudes, approaches, plastic growing bag and needs of farmers producing these commodities. Specialty crops are diverse. These crops can best be defined by exclusion—as all agricultural crops excluding grain crops , oil seeds , cotton, peanuts, and tobacco.

The bulk of specialty crops consist of fruits and nuts, vegetables, and ornamental crops . The industries featured in this study accounted for more than $16 billion of gross farm revenue in 2001. This value was more than 90 percent of the state’s total crop value and 60 percent of total agricultural value produced in California at the farm level. These industries are also important nationally. California accounts for 37 percent of the total value of horticultural crop production in the United States. In the past, these industries have expanded steadily in California, adding more than 300,000 acres between 1992 and 1997 . In the future, California’s horticultural industries are expected to continue to expand in size and importance. For the most part, horticultural growers have not been major recipients of farm program subsidies and have had relatively little government support compared to growers of commodities such as grains, oil seeds, cotton, sugar, and dairy products. Some horticultural crops have been eligible for USDA crop insurance programs and ad hoc disaster assistance, promotion assistance, and miscellaneous support, but the degree of subsidy has been small—typically around 5 percent of total value, compared to 30 to 50 percent and higher for grains, oil seeds, and cotton . Horticultural crops differ from other kinds of crops in their product characteristics, production processes, and market environments and thus in their risk characteristics. The design of public policy for these crops must reflect management of their unique risks.

Knowledge of market variables and grower risk behavior is essential to developing effective risk management tools for horticultural crops. Unfortunately, while studies on traditional crops abound, little research has been done on horticultural crops. The objective of this survey was to generate wide-ranging statistical information that can be used broadly to better understand the horticultural crop industry, its sources of risk, and typical responses to those risks. The statistical profile of California’s horticultural producers presented here is the most exhaustive ever undertaken for this group. It draws on survey data collected from approximately one-third of all horticultural crop producers in the state. This report presents a large volume of information concisely. To do so, we summarize the methodology used to collect and tabulate the data; provide an overview of the seven topics addressed; and discuss the primary results. The discussion is organized by issue and includes a narrative describing the main findings for each topic. Selected figures and tables are included. The narrative is supplemented with a data section in the Appendix, which is organized into three parts. The first provides the response rate for each question in the survey. The second contains data tables organized by commodity category. The tables supplement the information presented in the narrative section with further disaggregated analysis. The last part of the Appendix provides the actual survey instrument.The first stage of the study, the survey of specialty crop growers, involved developing a questionnaire. The questionnaire was developed specifically for specialty crop growers based on the format of a survey instrument used previously , with input from RMA and from researchers who conducted an identical study in Florida, Pennsylvania, and New York. The California Agricultural Statistical Service assisted in formatting the questionnaire to facilitate its implementation. The final version of the survey instrument is presented in Appendix 3. We established the sample frame by defining a minimum number of acres required for a farm to qualify for the study using information from CASS’s database.

To be included in the study, a farm had to have at least five acres of perennial crops or at least two acres of annual specialty crops . This limit was designed to exclude very small farms that were unlikely to be commercial operations. The acreage criterion was applied to CASS’s database, which contains information on more than 60,000 farms in California . A total of 31,864 farms met the acreage limit with the crops selected for the survey. CASS conducted two rounds of mailings and one round of telephone interviews to collect completed surveys. In total, the two survey mailings garnered 7,391 responses. Those mailings were followed by telephone interviews of growers who had not responded by mail, which collected an additional 7,746 responses. In total, 15,137 responses were received . Relatively few farmers answered all 25 survey questions, which required responses in 192 cells. Under some “usability” criteria on the completeness of the DATA COLLECTION AND AGGREGATION answers, some responses were discarded.1 In total, 10,410 observations were entered into an electronic database file that was then transferred to the authors. Our primary analysis used only the horticultural-crop based sample, which consisted of 10,200 observations. Among non-crop categories, aquaculture producers provided the largest number of observations, allowing some statistical analysis of that industry. We provide data tables for aquaculture in Appendix 2 but omitted aquaculture from the narrative analysis. Note that sample size used in our analysis varies depending on the question being analyzed. Survey responses varied in degree of completeness, and valuable information could have been lost if only fully completed responses were used. Thus, to maintain the maximum sample size, different sub-samples were used, depending on the usability and appropriateness of the data provided, in analyzing particular issues. Information on sample size is included in most of the table presentations.Several mountain ranges in California create the dominant Central Valley and smaller coastal valleys where much of the state’s agricultural production is concentrated. The large Central Valley consists of the Sacramento Valley, wholesale grow bags which lies north of the San Francisco Bay Delta, and the San Joaquin Valley, which lies south of the delta. The Central Valley is encircled by the Cascade ranges and Klamath Mountains to the north, the Sierra Nevada Mountains to the east, the coastal ranges to the west, and the Tehachapi Mountains to the south. The coastal ranges also create a long strip of valleys, including, for example, Napa Valley and Salinas Valley. . Climates in the region are affected by the cool currents of the Pacific Ocean and various mountain ranges. Temperatures in coastal regions are relatively mild while inland areas are hotter. Almost all of the state’s rain and snowfall occurs during late fall and winter . The majority of California’s water supply originates in the northern mountain regions of the state. Land for specialty crops is nearly all irrigated via ground water and various district, state, and federal water storage and distribution systems . California has 58 counties. In our analysis, we aggregated the counties into 11 regions with similar geographic and climatic characteristics as shown in Figure 1. The Sacramento Valley and San Joaquin Valley are together referred to as the Central Valley.California’s specialty crops include more than 200 individual crops. To facilitate a manageable analysis, crop aggregation was needed. First, all the commodities were assigned to one of five basic categories: field crops, fruits and nuts, vegetables, ornamental crops, and non-crop commodities. The last category included a small number of apiary and aquaculture farmers, but for category-specific analyses, we considered only aquaculture farmers because there were too few apiary farmers for any statistical analysis.

Fruits/nuts, vegetables, and ornamentals, which were our focus, were then further divided into subcategories of similar types of crops . The third level of classification identified specific crops. Our data analysis used mostly the first two levels of classification. See Table 1 for a detailed description of the classifications. While classification of fruits and nuts into the second level is self-evident, such classification of vegetables needs discussion. A wide variety of vegetables appears in the data and choosing transparent and intuitive yet manageable groups was difficult. Following USDA guidelines, nine botanical classifications of vegetables were aggregated into six groups, guided by climatic growing conditions and by the number of observations available.To highlight the results, we limited our analysis to the three primary crop categories—fruits/nuts, vegetables, and ornamental crops. The basic data set used in this analysis included only specialty crop farmers by excluding respondents whose primary commodity was listed as a non-crop or a field crop. With this exclusion, our basic data set consisted of 10,200 observations. Note, however, that much smaller samples were used in the analysis of many of the issues . In the following discussion we highlight only the major results for each topic. A fuller description of the data used for most charts and figures in this narrative can be found in Appendix 2.As a starting point, we present an overview of our sample and distributions of acreage and farms by region and by crop category. At the end of this section, we compare these distributions of survey respondents to those reported in the 1997 Census of Agriculture to illustrate the representativeness of the farms surveyed. Table A1 presents the share of farms and mean acres per farm by region and by crop category. Standard deviations are provided to give readers some sense of the variation in acreage. The three San Joaquin Valley regions accounted for 47 percent of the sample, the Sacramento Valley added another 13 percent, and the four coastal regions added 33 percent. The Far North, Sierra Nevada, and Desert regions comprised a substantial portion of the state’s land area, but only 7 percent of specialty crop growers in the sample were located in those regions and the average acreage per farm in those regions was below the state average. Fruit/nut growers represented about 86 percent of the sample; therefore, any data analysis on all crops tends to be dominated by the characteristics of fruit and nut farms. As shown in Table A1, mean acres varied considerably across crop categories but much less across regions. The average acreage for vegetable farms was substantially larger than the averages for fruit/nut and ornamental farms. On the other hand, average farm acres across regions were within the narrow range of 100–280 acres . The standard deviations for all acreage distributions reported in Table A1 were relatively high, meaning that the distributions were spread widely. To compare the degree of spread between distributions, the ratio of the standard deviation to the mean was calculated. The CV was seven for the whole sample and much higher in some regions. The South Coast’s CV of 15 was the largest. Of the crop categories, ornamentals had the largest variation in acreage. Table A2 provides the distribution of farms across finer crop classifications for each of the three main crop categories. Observations were classified into a subcategory based on farmers’ responses on their primary crops.3 Some facts stand out. Grape farms and nut farms each comprised more than 30 percent of all fruit/ nut farms, and nurseries comprised 67 percent of all ornamental farms. While almost one-third of vegetable farms grew tomatoes , the rest of the subcategories of vegetables were fairly evenly distributed. Table A3 provides the cumulative distributions by acreage class, which indicated that median per-farm acreage was between 21 and 30 acres for fruits/nuts and about 70 acres for vegetables. The same distributions are provided pictorially in Figure A1. About 40 percent of both fruit/nut and vegetable farms were concentrated around the land classes of 20 acres or less. Such high density of relatively small farms was common in the farm acreage distributions.

Kaplan’s support—and further pressure on Planning staff by City Council President Jane Brunner—was essential for getting the Planning Department to begin integrating urban agriculture into the current zoning update. The passage of SF’s urban agriculture ordinance also provided a significant boost to urban agriculture advocates in Oakland. Pesticide Watch, one of the NGOs active in the SFUAA helped to found the East Bay Urban Agriculture Alliance in February 2011. The organization, made up of a combination of “urban homesteaders” and food justice activists, has been engaged with the OFPC and Oakland-based NGO Bay Localize to finalize recommendations to the city for its integration into the zoning update. Many of the involved urban agriculture activists were also motivated by the highly publicized case of urban farmer and author Novella Carpenter who was cited for non-compliance with city permit requirements . Under mounting pressure both from City Council and the public, the Planning Department launched a plan to update urban agriculture zoning, a process that has galvanized community members, plastic nursery plant pot as evidenced by the July 2011 meeting I discuss in the dissertation’s introduction.

The first phase of the zoning update, approved by City Council in October 2011, was the legalization of sales of produce grown in home gardens . While these changes at the policy level to scale up urban agriculture are only beginning in Oakland, they signal a transition from lip service to implementation on the part of municipal government. Indeed, Planner David Ralston captures the shift in the receptivity of city officials, “Now they won’t laugh you out of town when you talk about urban agriculture” . In a modified version of the People’s Grocery logo that briefly appeared on fundraising website for non-profits, a white male in a baseball cap stands to the left of the other three young urban farming activists, one hand on a shovel, the other on the Asian male’s shoulder . This addition seems odd at first, an apparent afterthought, or perhaps a nod toward politically correct multicultural inclusiveness, or simply a more accurate representation of Oakland’s demographic make-up. But the addition also befits the story of the rise of the contemporary urban agriculture movement in Oakland. At each historical moment, from the Black Panthers to the EJ campaigns, to the rise of garden-based community food security and job training programs and urban agriculture’s current food justice-oriented incarnation, the success of urban agriculture activism has depended on multiracial, cross-class coalitions; indeed, as history sadly tells us, such alliances are necessary because the efforts of the poor acting alone are likely to be crushed. In addition to capturing the demographic of the 21st century urban agriculture movement , grounded in the ideology of food justice, the alternate logo pays homage to the radical groundwork underlying the food justice movement.

In the cases of the Black Panther Party, the EJ movement, and Urban Habitat, activists challenged the racial, political, economic, and ecological disparities between the flatlands and the hills. The struggle for healthy food, clean air, and green space mobilized community members at these different moments. Their successes depended on the discursive rescaling of the language of struggle in a way that helped cultivate multiracial and cross-class alliances. Using the language of Cox , these groups were able to expand their spaces of engagement through this politics of scale, to defend and improve their spaces of dependence, their neighborhoods and the food they eat. These coalitions, in turn, were able to marshal the resources necessary to grow the movement, tilling up vacant lots for food production, education, and youth employment. As organizations grew with the slow trickle of public and private funding, they became legitimate in the eyes of funders, who then opened the spigot further. While the specific goals of the urban agriculture organizations varied, their gardens nevertheless served as training grounds and/or inspiration for the current generation of food justice-oriented urban agriculture activists, intent not only on teaching nutrition and science, but also on creating an alternative provisioning strategy in Oakland’s flatlands while raising awareness of the structural inequities of the corporate food regime. Returning to the logo, the rays of sunlight beaming upwards, silhouetting the urban skyline and raised fists of the activists, embody the hope and vision of the food justice movement, the dawn of a just and equitable food system that contributes not only to the health of the city’s inhabitants, but also to broader goals of environmental sustainability and economic justice. On one level, these urban agriculture organizations have helped to move Oakland closer to these goals, as the growing patchwork of gardens and food policy attest.

On another level, however, the increasing institutionalization of the urban agriculture movement begs the question: what has been lost as these efforts have been formalized, as funding ebbs from one urban agriculture initiative and flows to another, as cross-class, multiracial coalitions are formed, as action in the streets and vacant lots and gardens is translated into grant proposals and zoning codes? Furthermore, can we consider urban agriculture to be radical? To what extent does urban agriculture actually function as an alternative provisioning system and what is the extent of its reach? I conclude by highlighting a few key considerations. First, let me reiterate the absence of the city’s majority urban farmers in the contemporary urban agriculture movement, the immigrant and migrant populations who continue to grow food for home consumption and maintenance of cultural traditions . Food justice activists use this form of urban agriculture as symbolic capital to strengthen their claims, frequently proffering it as an example of urban agriculture’s contribution to food security, neighborhood beautification, cultural value, and ecological sustainability. As urban agriculture has become a movement, however, largely dominated by a multiethnic group of young, educated, middle class activists, these urban farmers play a limited role in defining the urban agriculture movement as a movement. While some reap the benefits of urban agriculture programs—garden space at a new community garden, for example—many are simply unaware that a movement even exists. Second, the institutionalization of the urban agriculture movement has depended on funding. Organizations frequently compete for the same modest grants and end up fighting for proverbial crumbs. Moreover, these crumbs, in turn, can ultimately define the missions of the organizations. If the funding “flavor of the month” happens to be school gardens, seedling starter pot then school gardens become a central focus of the activity of these organizations . Many urban agriculture activists are quite aware of this dependent relationship, as well as the dependence of communities on outside NGOs for the implementation of urban agriculture and other programs. The centrality of the “non-profit industrial complex” is, in many ways, simply an outgrowth of the so-called neoliberal turn, where NGOs have rolled out to fill in the gaps in the social safety net left by the roll back of the Keynesian welfare state . The ability of such a movement, so dependent on relatively small flows of public and private funding, to effect structural change or create a just alternative to the corporate food regime , much less to sustain itself, is doubtful. Finally, the scalar politics employed by urban agriculture activists and their radical antecedents exemplify the power of coalition building and the ability to slowly shift the dominant paradigm surrounding the food system, slowly revealing its connections to city planning and public health. Ultimately the story of urban agriculture in Oakland is one of urban agriculture’s de-radicalization and its institutionalization into the mainstream. But rather than a story of its urban agriculture’s appropriation by the mainstream, it is a story of change arising from within the system due precisely to urban agriculture’s new place within the system.97 Changes are taking place on some structural level as food policy is slowly drafted, adopted, and implemented. The extent to which these changes, piecemeal and limited in reach, coalesce and evolve into a robust framework of incentives and regulation that truly challenges the corporate food regime remains to be seen.The ratio of workers to full-time-equivalent jobs in an industry is one important measure of the nature of the labor market.

Over the last several decades, seasonal industries such as construction have restructured in ways that have reduced the ratio of workers to FTE jobs. To evaluate this aspect of the agricultural labor market in California, we analyzed data collected by the California Employment Development Department in 2016 and compared key findings with our earlier analysis of similar data from 2015.How many people work for wages in California agriculture? Answering this question has been surprisingly difficult, largely because most farm jobs are seasonal, lasting from several weeks to several months, and there is high turnover, with many workers trying farm work and soon quitting. EDD publishes data on farm employment for the payroll period that includes the 12th of the month; in 2016, EDD data indicated that average monthly farm employment was 425,400. This 425,000 average is not a count of all individuals employed in agriculture, because some workers were employed but not during the payroll period that includes the 12th of the month. Including these not-on-payroll during the 12th of the month workers provides a count of all workers employed in agriculture. EDD does not report the total number of unique farm workers. This article fills this information gap, finding that there were about 2.3 workers for each average or FTE job. All California employers who pay $100 or more in quarterly wages are required to report each quarter their employees for the payroll period that includes the 12th of the month and the wages paid to all workers during the quarter, and to submit appropriate unemployment insurance taxes. In 2016, some 16,150 California agricultural establishments — North American Industry Classification System code 11, including farming, forestry, fishing and hunting — hired a monthly average 425,400 workers and paid them a total of $13.7 billion. The data also show that over the past decade, the number of agricultural establishments fell over 10%, average employment rose over 10%, and total wages rose 50%. Over 99% of the agricultural establishments that report employment are farms or firms supporting farms such as farm labor contractors . There are very few workers who had their maximum earnings in forestry, fishing and hunting, only 0.8%. We use “farm worker” in this paper to mean all workers employed in agriculture, including supervisors and accountants employed by farms, acknowledging that a few are employed in forestry, fishing and hunting. The average monthly employment of 425,400 reported by EDD represents 12 monthly snapshots of persons on the payroll during the payroll period that includes the 12th of the month. As such, it is a measure of the number of FTE positions in agriculture in California. Employers do not report hours of work, so some of the workers on the payroll may have worked full time and others part time. The $13.7 billion total wage figure represents payments to all workers, including those who were employed at other times of the month but not during the payroll period that includes the 12th. Dividing $13.7 billion by 425,400 gives $32,316, which would be the average annual salary of a full-time farm worker. However, since many farm workers are employed fewer than 2,080 hours a year, average earnings for the individuals who do farm work are significantly less; our analysis of earnings by individual workers indicates that the average earnings from all jobs of all workers with at least one job in California agriculture was $19,762 in 2016. To investigate this difference, we captured all workers reported by an agricultural employer, tallying a total of 989,500 individual workers in 2016. This process allows us to compare the total number of farm workers with the monthly average number of farm jobs. Figure 1 shows that this ratio has been rising from two workers per average job in 2014 and 2015 to 2.3 workers per average job in 2016, suggesting more workers tried farm work. The analysis is based on Social Security numbers reported by agricultural employers when paying UI taxes. Because we had data on all of the California jobs associated with each individual SSN reported by an agricultural employer, we could assign each worker to the NAICS code in which he or she had their highest earnings. This procedure identified 804,200 workers who worked primarily in agriculture .

A 1910 promotional booklet published by the Oakland Chamber of Commerce features a world map with all shipping lines leading to “Oakland Opposite the Golden Gate, The Logical Port and Industrial Center of the Pacific Coast” . 47 Worker housing emerged primarily in West Oakland, between the downtown business district and the rail and shipping terminus. The displacement of San Francisco residents following the 1906 earthquake was a boon for Oakland, bringing in a new workforce and new demands for housing. With population and industry growing at a rapid pace and aided by the extension of horsedrawn and electric streetcar lines, Oakland expanded to the north and east, annexing previously autonomous communities such as Temescal, Claremont, Brooklyn, Fruitvale, Melrose, and Elmhurst by 1909 . World War I saw a massive influx of military capital into Oakland. Automotive manufacturers such as the Durant Motor Company, Hall-Scott Motor Company, Chevrolet, and General Motors expanded considerably during these years, bucket flower earning Oakland the moniker “Detroit of the West.” Shipbuilding dominated the port, and employed upwards of 40,000 in 1920.

Drawn by the promise of jobs, new workers, many of them African Americans and immigrants, flooded in by the thousands. Wartime industrialization and the boom that continued through the ‘20s saw the expansion Oakland’s residential development alongside the construction of new factories eastwards into the orchards and pastures of the annexed townships . Integrating the pragmatism of locating industry where land was available with the reformist planning vision of Ebenezer Howard and Lewis Mumford, planners and developers in Oakland embraced the paradigm of the “industrial garden”: the dispersal of industry away from the mixed-use downtown core but closely tied to nearby, semiautonomous residential neighborhoods. In these industrial garden suburbs, factory workers would return home by bus or rail to a neighborhood of small, single-family homes, each with a yard or garden. Proponents pushed “garden living” in these quiet and tranquil respites far—but not too far—from the factory grind as a cure to the social and health risks already well documented in the mixed-use urban slums of the Northeast, Chicago, and to a lesser extent in the older downtown cores of San Francisco, Oakland, and Los Angeles . Urban and rural modes of survival came together here, as workers clocked out and headed home to tend vegetables, chickens, and goats in their yards .

As Mike Davis writes, the industrial garden was “a new kind of industrial society where Ford and Darwin, engineering and nature, were combined in a eugenic formula that eliminated the root causes of class conflict and inefficient production” ; in essence, by keeping the worker happy, productivity could increase while nipping a restive labor movement at the bud. During the New Deal the vast expanse of small homes that had cropped up as part of the industrial garden expanded rapidly. Beginning in 1934, a flood of highly subsidized, low-interest mortgage loans from the newly created Federal Housing Administration fed the growing suburbs; East Oakland soon filled in with suburban developments of small Mediterranean-style single-family homes. As in other California industrial centers, developers consolidated land purchase, subdivision, construction, and sales in order to maximize efficiency and minimize costs. Vast tracts of small houses, mostly prefabricated or built from kits with nearly identical floor plans, created an economy of scale that dovetailed nicely with the contemporary planning vision of neighborhood cohesion, mixed use, and garden cities to create quintessential industrial gardens. In order to expand homeownership, housing production had to be reorganized into a quasi-Fordist system of on-site assembly of prefab components to perfect the “minimum house”: a small, single-family home constructed as cheaply as possible but comfortable and unique enough to satisfy the dream of home ownership . The newly subdivided suburban landscape was rapidly filled in with these small, single-family homes erected virtually overnight. However, market forces alone were not responsible for the shifting landscape. While the social idealism of Ebenezer Howard’s garden cities and Lewis Mumford’s inclusive “eco-topian” regions undergirded the vision of many suburban planners, the pragmatism of industrial location, the whims of individual developers, and the rising power of racist homeowners’ organizations soon elided their utopian vision.

Indeed, the flows of capital defining Oakland’s urban landscape were clearly racialized. The federally-subsidized dream of homeownership in the industrial garden was not available to everyone; people of color rarely qualified for FHA loans because these were to be applied only to newly constructed homes and, contrary to Howard’s vision of universalist garden cities that welcomed and nourished all workers, new home developments in the suburban industrial gardens were racially exclusive. Until 1948 racial covenants established by developers and homeowners’ associations prevented people of color from moving in and disturbing social divisions seen as “natural” . Even after the Supreme Court made racial covenants illegal via Shelley v. Kraemer in 1948, such obstacles remained in practice. Contractors were rarely able to secure loans for construction for non-whites in a “Caucasians only” neighborhood and realtors feared “the wrath of white homeowners” . The racialized demarcation of urban space taking place between the wars was not new in California. For decades the labor movement in California had already laid the groundwork for the formation of a virulent form of white class-consciousness via their aggressive exclusion of Asian, Latino, and African American workers . Easy access to low-cost, single-family homes in close proximity to East Oakland’s factories simply fueled racist and exclusionary sentiments by creating a sense of bootstrap entitlement. Homeownership thus helped heterogeneous European and Euro-American populations of workers consolidate as a spatially and racially homogenized labor force of “whites,” geographically distinct from the radicalism of recent European immigrants and African Americans in West and North Oakland and along the estuary.48 Suburbanization of industry and housing was thus a way to escape from the working class and “to attract a better brand of labor, removed from the ‘bad moral atmosphere’ of the inner city, and promising the stability of homeownership for the ‘better class’ of workers” .If industrial relocation and FHA-funded residential development were the source of capital flows that irrigated East Oakland’s industrial garden from the 1920s to the ‘40s, homeowners associations, zoning, and redlining were the dikes that initially prevented this capital from flowing back towards West Oakland, and then effectively quarantined its devaluation to the few areas where people of color were allowed to live. New capital continued to flow in. Between January 1945 and December 1947 roughly $300 million was spent on the expansion of new industrial plants in the Bay Area . Within the city itself, however, devalued fixed capital—a landscape of aging housing stock and obsolete factories— left little room for new industry to take root. A highly coordinated growth machine of industry, developers, boosters, cut flower bucket and white laborers driven by the promise of homeownership and jobs diverted this latest flow of capital to the green fields of the newly incorporated industrial suburbs—San Leandro, Hayward, Fremont, San Lorenzo, Newark, Union City, Milpitas—that flanked the East Bay between Oakland and San Jose. Vast tracts of agricultural land were incorporated into these pro-business municipalities, zoned as industrial, and sold for prices below industrial land prices in Oakland. National companies such as General Motors and Caterpillar built branch plants on these fertile green fields, and defense contracts showered the new industrial suburbs with federal capital, ensuring rapid growth. As the data in Table 2.1 illustrate, manufacturing nearly doubled in Alameda County between 1948 and 1967. Here at the urban edge of the new suburbs, industry was given a tabula rasa. In essence, these new suburban municipalities provided a more favorable business climate, spatially removed from the pressure cooker of the urban center’s working class and the grip of recalcitrant city politicians . In the words of the Bay Area Council, which helped drive industrial suburbanization, suburban employees were “more loyal, more cooperative, more productive workers than those in big cities” . The implicit message to future investors was that this suburban workforce was largely white.Just as in East Oakland during the interwar years, industry and housing in the new suburbs went hand in hand, part of a concerted planning effort to disperse industry and the suburban residential developments that followed in its stead. These industrial shifts and the prosperity of the post-war era further fertilized the American dream of homeownership.

Large scale housing developments in the urban periphery and the expansion of automobile ownership cultivated suburban development and white flight, draining urban areas of their tax base. Just as the industrial garden of East Oakland was watered with a strong mix of industrial and residential capital during the World War I and 1920s boom years, and with capital available through FHA loans in the ‘30s and ‘40s, the new industrial garden suburbs grew rapidly in the post World War II era as a result of this same combination of industrial capital and federal housing subsidies. As Oakland de-industrialized and new factories sprouted in the suburbs, working class white Oaklanders followed, lured by homeownership and proximity to jobs, just as they had done in the previous wave of inter-war and wartime suburbanization. Between 1949 and 1951 only 600 units among the 75,000 constructed in the Bay Area were open to blacks . Upwardly mobile whites left the East Oakland flats to join the downtown ruling elite in their Oakland foothills and hillside neighborhoods, taking their cash with them. In Elmhurst, for example, white residents made up 82 percent of the neighborhood’s population in 1960 and median income was $6,154, only about 2 percent lower than the citywide median income; a decade later whites made up only slightly more than a third, while on the other side of the city boundary in San Leandro, people of color were excluded. As capital was channeled into the industrial suburbs, it began to dry up inside the city’s boundaries, leaving the once-verdant urban economy parched of tax revenue. By the mid 1960s, the number of manufacturers within Oakland had begun its steady decline. Between this downward trajectory and the steady growth of manufacturing in the new industrial suburbs, Oakland’s share of Alameda County’s industrial productivity dropped from more than half to less than a third in the four decades following World War II .55 More than 130 factories shut their doors and nearly 10,000 manufacturing jobs were lost by 1977 . Unemployment skyrocketed as a result. The unemployment rate in 1964 was 11 percent but for blacks was almost twice that high. Business ownership was absentee for the most part; by 1978, only 25 percent of businesses in East Oakland were locally-owned . This trend continued in the ‘80s as jobs shifted from the traditional manufacturing and warehousing sectors to a service-based industry. The Bay Area on the whole benefited from a boom during this period, with a 15 percent growth in jobs between 1981 and 1986. Oakland, however, reaped little in the way of this regional bounty; employment grew only by 1.5 percent during these same years. The flatlands bore the brunt of job loss during this period. West Oakland and Fruitvale lost eight to ten percent of jobs. In the Elmhurst and San Antonio districts, employment decreased by roughly a third . As East Oakland’s industrial garden withered and whites fled to the suburbs and hills, housing there became available to upwardly mobile people of color for the first time. The Oakland border with San Leandro truly became a color line. Just as East Oakland’s industrial garden communities had excluded people of color via racial covenants, new housing developments in places like San Leandro and San Lorenzo excluded people of color using racial covenants and informal “gentlemen’s agreements” between realtors and homeowners’ associations. Creating a class alliance with developers, increasingly conservative white homeowners in the new suburbs helped to exert political pressure to further confine devaluation to the Oakland flatlands. Proposition 14, a 1964 ballot initiative sponsored by the California Real Estate Association and supported by 65 percent of voters statewide, essentially overturned the federal Fair Housing Act, passed the year before. In 1978 this same alliance was able to pass the infamous Proposition 13, which severely limited cities’ ability to raise property taxes. The resulting decrease in property taxes took a toll on Oakland’s already impoverished flatlands, as inflow of revenue was squeezed by more than $14 million, leading to facilities closures and cuts to public services .

While seasonal droughts are known to be a natural and regular occurrence in arid and semi-arid regions, the increased frequency, duration, and intensity with which they have occurred in recent years is highly unusual . Such extreme droughts, referred to as “global-change type drought” , are predicted to continue, and even become the norm, as a result of human-induced climate change . Consequently, species that are typically capable of withstanding regular drought stress may be susceptible to canopy dieback, and mortality, as a result of shifts in drought regimes . Chaparral shrublands, which occupy approximately 7 million acres throughout California , are a dominant vegetation community in southern California, composed primarily of evergreen, drought tolerant shrubs and subshrub species including manzanita , ceanothus , and chamise . These species are well adapted to the seasonal variations in temperature and precipitation typical of mediterranean climates where hot, rainless summers are the norm . However, mediterranean-type regions like southern California are predicted to experience rapid increases in temperature , procona London container and increased drought occurrence and severity ; IPCC, 2013, resulting from human-caused climate change.

These regions have thus been designated as worldwide global change “hot spots” . Indeed, recent studies have reported extensive mortality of chaparral shrub species resulting from global-change type drought throughout southern California . Thus, climate change represents a significant threat to native plant community persistence in this region. A critical topic for ecological research is understanding where, how, and to what extent plant communities will change as a result of increased drought . Studies aimed at understanding the physiological mechanisms behind drought-related plant mortality – and why some plants suffer mortality from drought while others survive – have elucidated a variety of complex mechanisms of plant mortality . These include loss of hydraulic conductance , exhausted carbon reserves , and susceptibility to pests and pathogens due to being in a weakened state from drought . Measuring xylem pressure potential can be a useful index of soil water availability , and dark-adapted fluorescence can be a quick and accurate indicator of plant stress, as values drop significantly in water-stressed plants, . Together, these may be useful tools for predicting plant vulnerabilities to drought and biotic invasion. Landscape variables such as elevation, slope, and aspect have also been shown to correlate with plant water stress and mortality , and can be useful for predicting vulnerabilities during drought.

However, major knowledge gaps still remain, and studies combining field mortality patterns with physiological data on plant water stress are rare . Plants employ a variety of complex strategies to cope with drought stress, but generally fall along a continuum of “drought avoiders” or “drought tolerators”. Drought avoidance, also known as “isohydry”, refers to plants that regulate stomatal conductance to maintain high minimum water potentials as soil dries out . While this strategy reduces the risk of xylem cavitation and subsequent hydraulic failure, it may increase the likelihood of carbon starvation, as C assimilation is greatly reduced . Conversely, drought tolerant plants maintain higher Gs, even at very low water potentials, which allows for continued C assimilation but with greater risk of xylem cavitation . These different strategies can have significant implications for ecosystemlevel consequences of severe drought ; indeed, recent studies have linked anisohydry with greater levels of mortality in chaparral systems . An historic drought in southern California provided an opportunity to simultaneously measure physiological stress and dieback severity along an elevational gradient in a classically drought-tolerant evergreen chaparral shrub, big berry manzanita . A. glauca is one of the largest and most widely-spread members in a genus consisting of nearly 100 species. Its range extends as far north as the Cascade mountains and south into Baja California, though it is most dominant in southern California shrublands .

They frequently occur on exposed ridges and rocky outcroppings. In the chaparral shrublands of Santa Barbara County, it occurs from elevations of about 500- 1200m. A. glauca are obligate seeders, and must recruit from the seedbank following fire . Compared to resprouters, which regenerate from a carbohydrate-rich burl at their base following fire, seeders tend to be fairly shallowrooted , and are thus less able to access deep water sources . Seeders are generally considered to be more tolerant of seasonal drought than resprouters , possibly a mechanism for shallowrooted seedlings to survive summer drought in an open post-fire environment following germination . However, this strategy has also been linked to higher mortality during extreme drought . A. glauca are also known to exhibit anisohydric mechanisms of drought tolerance , and can exhibit extremely low water potentials and high resistance to cavitation during seasonal drought . In 2014, we observed sudden and dramatic dieback in A. glauca in the Santa Ynez mountain range of Santa Barbara, California during an historic drought . The drought that lasted from 2012 to 2018 in southern California was the most severe to hit the region in 1,200 years , with 2014 being the driest year on record . Preliminary field observations indicated greater levels of canopy dieback at lower elevation stands compared to higher elevations. Dieback also seemed to be more prevalent on exposed and southwest-facing slopes, which in this region experience direct sunlight for most of the day. Other studies have reported significant Arctostaphylos spp. dieback and even mortality during periods of extreme drought stress, further suggesting species in this genus are vulnerable to drought-related mortality. Additionally, we observed widespread symptoms of fungal infection – including branch cankers and brown/black leaf discoloration – later identified as members of the opportunistic Botryosphaeriaceae family , suggesting multiple factors may be driving canopy dieback in this species. Drought-related mortality has previously been associated with opportunistic fungal pathogens in A. glauca and other chaparral shrubs , yet few studies have sought to understand the relative levels of drought stress incurred by plants infected with these pathogens, cut flower transport bucket or how stress is related to canopy dieback and/or mortality. A. glauca shrubs are important members of the chaparral ecosystem, providing habitat and food for wildlife through their nectar and berries . Their structure and fire-induced germination strategies also make them significant components of the chaparral fire regime and post-fire successional trajectories . Large-scale mortality of this species could reduce resource availability for wildlife, as well as alter fuel composition and structure in the region, resulting in an increased risk of more intense, faster burning fires. Therefore, the potential continued dieback of A. glauca is of great concern for both ecosystem functioning and human populations alike. Yet because of the heterogeneity of landscapes in this rugged region, it is possible that portions of the landscape will act as refugia for drought-susceptible species. We hypothesized that A. glauca dieback severity is associated with areas of increased water stress across the landscape. To better understand the patterns and trajectory of A. glauca stress and dieback across a topographically diverse region of coastal California, we asked the following specific questions: How severe is drought-related stress and dieback in this region? How do plant stress and dieback severity vary with elevation and aspect across the landscape? How does dieback change across the landscape as a multi-year drought progresses? We chose xylem pressure potential as an indicator of plant water availability, and measured dark-adapted fluorescence and net photosynthesis as proxies for drought-related plant stress and physiological function.

To address Question 1, we conducted an initial survey measuring general levels of canopy dieback, shrub water availability, and stress in the region. To address Questions 2 and 3, we conducted a more in-depth study of how shrub water relations and dieback vary with aspect and along an elevational gradient, and tracked changes in dieback severity for the four final years of the seven-year drought. We expected to find areas of low XPP correlated with greater physiological stress responses, and more severe dieback in lower elevation sites and on southwest aspects. Alternatively, shrub stress and dieback may be dependent on a wider variety of variables, particularly in a landscape as heterogeneous as this. Additionally, we predicted that dieback severity and individual shrub death would increase over time in lower elevations and exposed slopes compared to upper elevations and more mesic slopes. The specific area chosen for this study is located in the Santa Ynez mountains of Los Padres National Forest . Stands of A. glauca occur from approximately 400m to 1200m elevation, and are frequently mixed with other co-dominate woody evergreen shrub species including Adenostoma fasciculatum, Ceanothus megacarpus and, at lower elevations, Malosma laurina. The landscape of this region is extremely heterogeneous, with unstable terrain composed largely of sandstone rock outcroppings and sandstone-derived soils , and steep slopes and ridges that are interrupted by deep canyons . These dramatic features, while common habitat for chaparral plant communities, were a limitation in our ability to choose field sites. Thus, we relied heavily on accessibility by road and trail in finding sites. The climate in this region is of a mediterranean-type, with cool moist winters and a hot, dry summer season. The majority of rainfall typically occurs from November to April, and mean annual rainfall, based on a 120-year average, is 47cm .Three weather stations, equipped with real-time, self-recording data loggers and maintained by the Santa Barbara County Public Works Hydrology Division, were chosen to retrieve precipitation data during the drought based on proximity and similar elevation to study sites. The Trout Club , San Marcos Pass , and El Deseo Ranch stations represented low, intermediate, and high elevations, respectively. Data from these stations were retrieved from the Santa Barbara County Public Works Hydrology website.Average rainfall at these stations, based on 54-69 year means, increases with elevation from 68.3cm to 90.4cm . Annual rainfall data for this study are presented in “rainfall years” from November 1 of one year to October 31 of the next, to reflect the seasonal wet period preceding each sampling period. Consistent with these historical trends, annual rainfall at Trout Club was lowest between the 2014-15 and 2018-19 water years . However, during this same time period, rainfall totals were generally lower at El Deseo Ranch compared to San Marcos Pass . In 2015, an initial survey was conducted to assess dieback, as well as shrub water demand and physiological stress as the summer dry season progressed during the drought. Five sites were chosen for this survey representing variable elevation, slope, and aspect, but were also limited by access, safety and proximity to roads. Sites were defined as being composed of greater than 50% A. glauca cover, except for site C, which had lower than 50% A. glauca cover but favorable access. Boundaries were delineated using a combination of on-the-ground visual assessment and polygons drawn using 1m National Agriculture Imagery Program imagery within ArcGIS® . Later, they were refined using a Phantom 4 Pro Drone .Each site was initially assessed for A. glauca stand dieback severity and site mortality in winter, before new summer leaf-out occurred . Stand dieback severity was defined as the percent of non-green or defoliated canopy cover within the boundaries of the site, and was estimated by the collective valuation of two-to-three people viewing the stand from different angles. If stands were not completely pure A. glauca , we did not include canopies of other species in our estimation of average percent dieback. Data on stand mortality were collected by counting the number of dead individuals within site boundaries using ArcGIS. Number of dead individuals per site was also recorded. To measure shrub water availability and physiological stress through the summer dry season, twenty individuals per site were selected based on similar size , accessibility, and representing different levels of health along a continuum. From these twenty, ten individuals were randomly chosen using a random number generator and tagged for collecting repeated data on stress and dieback as the dry season progressed. At one site only nine individuals fell within the size criteria and were readily accessible, therefore the sample size for this site was nine, for a total of 49 shrubs used in this initial survey. All selected individuals were measured for height and canopy volume. Measurements included basal diameter , height, and canopy width in two directions.