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• 1. [Article] The relative contribution of climate to changes in lesser prairie-chicken abundance

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by the author(s) and ...

  Citation × Citation Citation Abstract Copy Title: The relative contribution of climate to changes in lesser prairie-chicken abundance Author: Haukos, David, Ross, Beth E., Hagen, Christian, Pitman, James To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by the author(s) and published by John Wiley & Sons, Inc. on behalf of the Ecological Society of American. It can be found at: http://esajournals.onlinelibrary.wiley.com/hub/journal/10.1002/%28ISSN%292150-8925/ Title: The relative contribution of climate to changes in lesser prairie-chicken abundance Author: Haukos, David, Ross, Beth E., Hagen, Christian, Pitman, James To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by the author(s) and published by John Wiley & Sons, Inc. on behalf of the Ecological Society of American. It can be found at: http://esajournals.onlinelibrary.wiley.com/hub/journal/10.1002/%28ISSN%292150-8925/ Close

• 2. [Article] Landscape-Level Approaches to Desert Bighorn Sheep (Ovis canadensis nelsoni) Conservation in a Changing Environment

  Landscape characteristics can strongly influence demographic and genetic processes in wildlife populations. Climate change and human land use are causing many landscapes to change rapidly, and the effects ...

  Citation × Citation Citation Abstract Copy Title: Landscape-Level Approaches to Desert Bighorn Sheep (Ovis canadensis nelsoni) Conservation in a Changing Environment Author: Creech, Tyler Graydon Landscape characteristics can strongly influence demographic and genetic processes in wildlife populations. Climate change and human land use are causing many landscapes to change rapidly, and the effects on wildlife populations must be understood to properly manage these threats and design effective conservation strategies. In this dissertation, I explored the implications of landscape heterogeneity for desert bighorn sheep (Ovis canadensis nelsoni), an ecologically and culturally important ungulate species in the southwestern United States, and demonstrated new approaches that can be applied to landscape-level conservation of many wildlife species in changing landscapes. This research focused on populations within and surrounding U.S. national parks, comprising a large portion of the desert bighorn sheep's geographic range, and utilized a genetic dataset including > 1,600 individuals that was developed during this and previous projects. Landscape resistance models have been used extensively to predict potential linkages among fragmented wildlife populations, including desert bighorn sheep, but have rarely been used to guide systematic decision-making such as prioritizing conservation actions to maximize regional connectivity. In Chapter 1, I combined network theory and landscape resistance modeling to prioritize management for connectivity, including protection and restoration of dispersal corridors and habitat patches, in a desert bighorn sheep metapopulation in the Mojave Desert. I constructed network models of genetic connectivity (potential for gene flow) and demographicconnectivity (potential for colonization of empty habitat patches). I found that the type of connectivity and the network metric used to quantify had substantial effects on prioritization results; however, I was able to identify high-priority habitat patches and corridors that were highly ranked across all combinations of the above factors. Potential diet quality varies across landscapes and through time for desert bighorn sheep and other ungulates, but is difficult to measure at fine spatial and temporal resolution using traditional field-based methods. The remotely sensed vegetation index NDVI can potentially overcome these limitations, but its relationship to diet quality has never been empirically validated for desert herbivores. In Chapter 2, I examined how strongly NDVI was associated with diet quality of desert bighorn sheep in the Mojave Desert using fecal nitrogen data from multiple years and populations, and considered the effects of temporal resolution, geographic variability, and NDVI spatial summary statistic. I found that NDVI was more reliably associated with diet quality over the entire growing season than with instantaneous diet quality for a population, and was positively associated with population genetic diversity (a proxy for long-term diet quality). Although NDVI was a useful diet quality indicator for Mojave Desert bighorn sheep, my analysis suggested that it may be unreliable if satellite data are too spatially coarse to detect microhabitats providing high-quality forage, or if diet is strongly influenced by forage items that are weakly correlated with landscape greenness. Landscape genetic studies typically rely on neutral genetic markers to explore gene flow and genetic variation, but the potential for species to adapt to changing landscapes depends on how natural selection influences adaptive genetic variation. In Chapter 3, I optimized landscape resistance models for desert bighorn sheep in three regions with different landscape characteristics, and then used genetic simulations incorporating natural selection to determine how the spread of adaptive variation is influenced by differences among landscapes. Optimized landscape resistance models differed between regions but slope, presence of water barriers, and major roads had the greatest impacts on gene flow. Differences among landscapes strongly influenced the spread of adaptive genetic variation, with faster spread in landscapes with more continuously distributed habitat and when a pre-existing allele (i.e., standing genetic variation) rather than a novel allele (i.e., mutation) served as the source of adaptive genetic variation. Climate change presents a substantial threat to desert bighorn sheep and wildlife worldwide, and adaptation may be required to persist in novel environmental conditions. Knowledge of how adaptive capacity - the potential to cope with climate change by persisting in situ or moving to more suitable ranges or microhabitats - varies across populations is needed to establish conservation priorities for minimizing climate change impacts to individual species. In Chapter 4, I explored variation in the evolutionary component of adaptive capacity for 62 desert bighorn sheep populations on and near U.S. national parks. I measured adaptive capacity of populations as a function of two factors that are strongly associated with the potential for evolutionary adaptation, genetic diversity and connectivity (estimated using a landscape resistance model from Chapter 3). Genetic diversity and connectivity were highly variable across regions and populations. I identified populations with high adaptive capacity that could serve as genetic refugia from climate change impacts (e.g., those in Death Valley and Grand Canyon National Parks), but also populations with low adaptive capacity that may require conservation actions to improve their potential for adaptation (e.g., those in eastern Utah and the southern Mojave Desert). Genetic structure analyses suggested that populations in eastern Utah were genetically distinct from the rest of the study area, likely resulting from restricted gene flow following regional population extinctions. This dissertation highlighted the effects of landscape heterogeneity on genetic and demographic processes in desert bighorn sheep populations. Collectively, the information in these chapters should help guide management of desert bighorn sheep in the face of climate change and human land use. The landscape-level approaches demonstrated here may be useful for managing many other wildlife species. Title: Landscape-Level Approaches to Desert Bighorn Sheep (Ovis canadensis nelsoni) Conservation in a Changing Environment Author: Creech, Tyler Graydon Landscape characteristics can strongly influence demographic and genetic processes in wildlife populations. Climate change and human land use are causing many landscapes to change rapidly, and the effects on wildlife populations must be understood to properly manage these threats and design effective conservation strategies. In this dissertation, I explored the implications of landscape heterogeneity for desert bighorn sheep (Ovis canadensis nelsoni), an ecologically and culturally important ungulate species in the southwestern United States, and demonstrated new approaches that can be applied to landscape-level conservation of many wildlife species in changing landscapes. This research focused on populations within and surrounding U.S. national parks, comprising a large portion of the desert bighorn sheep's geographic range, and utilized a genetic dataset including > 1,600 individuals that was developed during this and previous projects. Landscape resistance models have been used extensively to predict potential linkages among fragmented wildlife populations, including desert bighorn sheep, but have rarely been used to guide systematic decision-making such as prioritizing conservation actions to maximize regional connectivity. In Chapter 1, I combined network theory and landscape resistance modeling to prioritize management for connectivity, including protection and restoration of dispersal corridors and habitat patches, in a desert bighorn sheep metapopulation in the Mojave Desert. I constructed network models of genetic connectivity (potential for gene flow) and demographicconnectivity (potential for colonization of empty habitat patches). I found that the type of connectivity and the network metric used to quantify had substantial effects on prioritization results; however, I was able to identify high-priority habitat patches and corridors that were highly ranked across all combinations of the above factors. Potential diet quality varies across landscapes and through time for desert bighorn sheep and other ungulates, but is difficult to measure at fine spatial and temporal resolution using traditional field-based methods. The remotely sensed vegetation index NDVI can potentially overcome these limitations, but its relationship to diet quality has never been empirically validated for desert herbivores. In Chapter 2, I examined how strongly NDVI was associated with diet quality of desert bighorn sheep in the Mojave Desert using fecal nitrogen data from multiple years and populations, and considered the effects of temporal resolution, geographic variability, and NDVI spatial summary statistic. I found that NDVI was more reliably associated with diet quality over the entire growing season than with instantaneous diet quality for a population, and was positively associated with population genetic diversity (a proxy for long-term diet quality). Although NDVI was a useful diet quality indicator for Mojave Desert bighorn sheep, my analysis suggested that it may be unreliable if satellite data are too spatially coarse to detect microhabitats providing high-quality forage, or if diet is strongly influenced by forage items that are weakly correlated with landscape greenness. Landscape genetic studies typically rely on neutral genetic markers to explore gene flow and genetic variation, but the potential for species to adapt to changing landscapes depends on how natural selection influences adaptive genetic variation. In Chapter 3, I optimized landscape resistance models for desert bighorn sheep in three regions with different landscape characteristics, and then used genetic simulations incorporating natural selection to determine how the spread of adaptive variation is influenced by differences among landscapes. Optimized landscape resistance models differed between regions but slope, presence of water barriers, and major roads had the greatest impacts on gene flow. Differences among landscapes strongly influenced the spread of adaptive genetic variation, with faster spread in landscapes with more continuously distributed habitat and when a pre-existing allele (i.e., standing genetic variation) rather than a novel allele (i.e., mutation) served as the source of adaptive genetic variation. Climate change presents a substantial threat to desert bighorn sheep and wildlife worldwide, and adaptation may be required to persist in novel environmental conditions. Knowledge of how adaptive capacity - the potential to cope with climate change by persisting in situ or moving to more suitable ranges or microhabitats - varies across populations is needed to establish conservation priorities for minimizing climate change impacts to individual species. In Chapter 4, I explored variation in the evolutionary component of adaptive capacity for 62 desert bighorn sheep populations on and near U.S. national parks. I measured adaptive capacity of populations as a function of two factors that are strongly associated with the potential for evolutionary adaptation, genetic diversity and connectivity (estimated using a landscape resistance model from Chapter 3). Genetic diversity and connectivity were highly variable across regions and populations. I identified populations with high adaptive capacity that could serve as genetic refugia from climate change impacts (e.g., those in Death Valley and Grand Canyon National Parks), but also populations with low adaptive capacity that may require conservation actions to improve their potential for adaptation (e.g., those in eastern Utah and the southern Mojave Desert). Genetic structure analyses suggested that populations in eastern Utah were genetically distinct from the rest of the study area, likely resulting from restricted gene flow following regional population extinctions. This dissertation highlighted the effects of landscape heterogeneity on genetic and demographic processes in desert bighorn sheep populations. Collectively, the information in these chapters should help guide management of desert bighorn sheep in the face of climate change and human land use. The landscape-level approaches demonstrated here may be useful for managing many other wildlife species. Close

• 3. [Article] Building on Two Decades of Ecosystem Management and Biodiversity Conservation under the Northwest Forest Plan, USA

  Correction: We discovered two typos and a change in a sentence needed in our published manuscript. Regarding the typos: timber estimates in Section 2 of the NWFP’s Long-Term Objectives should have been ...

  Citation × Citation Citation Abstract Copy Title: Building on Two Decades of Ecosystem Management and Biodiversity Conservation under the Northwest Forest Plan, USA Author: DellaSala, Dominick A., Baker, Rowan, Heiken, Doug, Nelson, S. Kim, et al. Correction: We discovered two typos and a change in a sentence needed in our published manuscript. Regarding the typos: timber estimates in Section 2 of the NWFP’s Long-Term Objectives should have been 2.34 million cubic meters annually instead of 234 million cubic meters annually and ~1.78 million cubic meters instead of 178 million cubic meters annually. The statement regarding murrelet populations—“Trends were downward (but not significant) in other NWFP states” should be deleted in this paper [1]. The authors would like to apologize for any inconvenience caused to the readers by these changes. Title: Building on Two Decades of Ecosystem Management and Biodiversity Conservation under the Northwest Forest Plan, USA Author: DellaSala, Dominick A., Baker, Rowan, Heiken, Doug, Nelson, S. Kim, et al. Correction: We discovered two typos and a change in a sentence needed in our published manuscript. Regarding the typos: timber estimates in Section 2 of the NWFP’s Long-Term Objectives should have been 2.34 million cubic meters annually instead of 234 million cubic meters annually and ~1.78 million cubic meters instead of 178 million cubic meters annually. The statement regarding murrelet populations—“Trends were downward (but not significant) in other NWFP states” should be deleted in this paper [1]. The authors would like to apologize for any inconvenience caused to the readers by these changes. Close

• 4. [Article] Climate change outreach project : final report

  INR’s mission is to provide Oregonians with ready access to current, science‐based information and methods for better understanding resource management challenges and developing solutions and after the ...

  Citation × Citation Citation Abstract Copy Title: Climate change outreach project : final report Author: Institute for Natural Resources, Yaden, David, Gaines, Lisa, Orscheln, Nell, Davis-Born, Renee, Achterman, Gail, Rice, Bronwen INR’s mission is to provide Oregonians with ready access to current, science‐based information and methods for better understanding resource management challenges and developing solutions and after the 2004 release of the Governor’s Advisory Group on Global Warming (GAGGW’s) extensive report, The Oregon Strategy for GHG Reductions, INR recognized the need for a grassroots understanding of the issues surrounding climate change in Oregon. INR subsequently was funded to implement Phase I of a three‐phased strategy to address the scientific information issue of climate change. 4 Climate Change Outreach Project Final Report This final report documents the efforts of the INR project team. Section 2 provides the project background, goals, and objectives. Section 3 describes how each of the objectives was achieved and their subsequent impacts. Section 4 highlights some of the overall lessons learned, while Sections 5 and 6 conclude the report by focusing on the project management and the report conclusions. Title: Climate change outreach project : final report Author: Institute for Natural Resources, Yaden, David, Gaines, Lisa, Orscheln, Nell, Davis-Born, Renee, Achterman, Gail, Rice, Bronwen INR’s mission is to provide Oregonians with ready access to current, science‐based information and methods for better understanding resource management challenges and developing solutions and after the 2004 release of the Governor’s Advisory Group on Global Warming (GAGGW’s) extensive report, The Oregon Strategy for GHG Reductions, INR recognized the need for a grassroots understanding of the issues surrounding climate change in Oregon. INR subsequently was funded to implement Phase I of a three‐phased strategy to address the scientific information issue of climate change. 4 Climate Change Outreach Project Final Report This final report documents the efforts of the INR project team. Section 2 provides the project background, goals, and objectives. Section 3 describes how each of the objectives was achieved and their subsequent impacts. Section 4 highlights some of the overall lessons learned, while Sections 5 and 6 conclude the report by focusing on the project management and the report conclusions. Close

• 5. [Article] Outcome Distributions in Impact Assessment : Climate Change and Technology Adoption in Pacific Northwest Agriculture

  Increased temperature and precipitation variability and frequent extreme weather events due to climate change pose a threat to farming operations and agricultural communities. The recent IPCC assessment ...

  Citation × Citation Citation Abstract Copy Title: Outcome Distributions in Impact Assessment : Climate Change and Technology Adoption in Pacific Northwest Agriculture Author: Zhang, Hongliang Increased temperature and precipitation variability and frequent extreme weather events due to climate change pose a threat to farming operations and agricultural communities. The recent IPCC assessment shows that the projected climate change will, on average, reduce wheat yields by 5% in temperate regions without adaptation and even more if temperatures continue to rise. Designing policies for helping climate-vulnerable farmers requires a comprehensive understanding of the impacts of climate change on agricultural systems and potential adaptation strategies. This dissertation consists of three essays that address several relevant issues from an economic perspective. The first essay presents an empirical analysis to assess the impacts of climate change on farm-level economic outcome distributions for winter wheat systems (including winter wheat yield, farm revenue, expenditure, and net return) in the U.S. Pacific Northwest by using a flexible moment-based approach. Results indicate that a warming climate, on average, reduces winter wheat yield but increases farm economic returns in this region, while droughts have a large negative impact on the ex-ante distributions of winter wheat yields and farm net returns. Using the econometric estimates, the farm-level climate vulnerability is quantified and examined. The second essay examines the effects of conservation tillage (including no-till and other conservation tillage) on winter wheat yield and production risk. We test the hypothesis that conservation tillage practices are risk-reducing. We use farm-level tillage practice data from the 2012 Agricultural Census for the U.S. Pacific Northwest. Results are estimated using a three-stage approach by integrating a multinomial logit model with a flexible moment-based approach. We find that conservation tillage has a negative effect on winter wheat productivity. We also find statistical evidence that conservation tillage is risk-increasing. Implications of the results for using conservation tillage to adapt to climate change are discussed. The third essay compares the difference-in-difference and fixed effects approaches to estimate long-term climate impacts versus short-term weather effects on U.S winter wheat systems. A county-level panel dataset is used to assess the effects of climate and weather variables on winter wheat yield and farm revenue in the U.S. Pacific Northwest and the central Great Plains. The net effect of a warming climate is found to be negative on the winter wheat production both in the short run and the long run. Implications of the results for short-term adjustments and long-term adaptations are discussed. Title: Outcome Distributions in Impact Assessment : Climate Change and Technology Adoption in Pacific Northwest Agriculture Author: Zhang, Hongliang Increased temperature and precipitation variability and frequent extreme weather events due to climate change pose a threat to farming operations and agricultural communities. The recent IPCC assessment shows that the projected climate change will, on average, reduce wheat yields by 5% in temperate regions without adaptation and even more if temperatures continue to rise. Designing policies for helping climate-vulnerable farmers requires a comprehensive understanding of the impacts of climate change on agricultural systems and potential adaptation strategies. This dissertation consists of three essays that address several relevant issues from an economic perspective. The first essay presents an empirical analysis to assess the impacts of climate change on farm-level economic outcome distributions for winter wheat systems (including winter wheat yield, farm revenue, expenditure, and net return) in the U.S. Pacific Northwest by using a flexible moment-based approach. Results indicate that a warming climate, on average, reduces winter wheat yield but increases farm economic returns in this region, while droughts have a large negative impact on the ex-ante distributions of winter wheat yields and farm net returns. Using the econometric estimates, the farm-level climate vulnerability is quantified and examined. The second essay examines the effects of conservation tillage (including no-till and other conservation tillage) on winter wheat yield and production risk. We test the hypothesis that conservation tillage practices are risk-reducing. We use farm-level tillage practice data from the 2012 Agricultural Census for the U.S. Pacific Northwest. Results are estimated using a three-stage approach by integrating a multinomial logit model with a flexible moment-based approach. We find that conservation tillage has a negative effect on winter wheat productivity. We also find statistical evidence that conservation tillage is risk-increasing. Implications of the results for using conservation tillage to adapt to climate change are discussed. The third essay compares the difference-in-difference and fixed effects approaches to estimate long-term climate impacts versus short-term weather effects on U.S winter wheat systems. A county-level panel dataset is used to assess the effects of climate and weather variables on winter wheat yield and farm revenue in the U.S. Pacific Northwest and the central Great Plains. The net effect of a warming climate is found to be negative on the winter wheat production both in the short run and the long run. Implications of the results for short-term adjustments and long-term adaptations are discussed. Close

• 6. [Article] Amphibian communities and climate change: where ecological processes meet evolutionary interactions

  Forecasts of the impacts of climate change have traditionally focused on individual species and their phenotypes, phenology, or distribution. However, shifts in species distributions and the resulting ...

  Citation × Citation Citation Abstract Copy Title: Amphibian communities and climate change: where ecological processes meet evolutionary interactions Author: Thurman, Lindsey L. Forecasts of the impacts of climate change have traditionally focused on individual species and their phenotypes, phenology, or distribution. However, shifts in species distributions and the resulting reorganization of community composition represent an important violation to the assumption of species acting in isolation. Whereas species may respond individualistically to climate change, the manifestations of their responses will be largely influenced by interactions with other organisms. Tractably dealing with complex interaction networks in the face of climate change will require an understanding of community dynamics and the degree to which biotic interactions influence species' behavior, physiology, and survival – and ultimately their footprint on the landscape. To improve our understanding of community-level responses to climate change, I explored amphibian response strategies from both a population- and community-level perspective and provided a critical evaluation of one of the primary methods for incorporating biotic interactions into predictive species distribution models. In Chapter 2, I evaluated amphibian species’ physiological constraints and the potential consequences of phenotypic plasticity as a first step to understanding their sensitivity, and ultimately, adaptive capacity to climate change. I experimentally quantified phenotypic plasticity in larval growth and development in three high elevation Anuran species (Anaxyrus boreas, Pseudacris regilla, and Rana cascadae) in response to projected climate warming scenarios for the Cascade Mountain Range. Warming initiated faster weight gain and accelerated larval growth rates in each of the species. However, any effort to achieve optimum body size (in both length and weight), while maintaining the necessary developmental trajectory under heat stress, was relatively unsuccessful. In Chapter 3, I tested the response strategies of the same three Anuran species to a different climate stressors, hydroperiod reduction (i.e. drought), and included the additional stress of interspecific competition. I found that competition exacerbated the effects of drying on competitively inferior species (Anaxyrus boreas and Pseudacris regilla) and that, in general, species responses were largely context-dependent. My results emphasize the importance of biotic interactions in predictions of species response to climate change. In Chapter 4, I provide a critical evaluation of standard methods for incorporating biotic interactions into predictive species distribution models. Most methods utilize observational data via species co-occurrences on the landscape to infer the role of biotic interactions in structuring species distributions. Results from a series of tests using two long-term amphibian co-occurrence datasets from Mt. Rainier National Park (Washington) and Mt. Hood (Oregon) show that the current best available methods are largely disconnected from community ecology theory and have yet to reconcile the complex dynamics within trophically-structured communities. My research aims to fill a critical knowledge gap in the connection between community dynamics and biogeography, with significant implications for conservation and management of a severely threatened taxonomic group. I highlight the significant challenges of estimating species response to climate change across multiple levels of taxonomic organization and spatio-temporal scales. Title: Amphibian communities and climate change: where ecological processes meet evolutionary interactions Author: Thurman, Lindsey L. Forecasts of the impacts of climate change have traditionally focused on individual species and their phenotypes, phenology, or distribution. However, shifts in species distributions and the resulting reorganization of community composition represent an important violation to the assumption of species acting in isolation. Whereas species may respond individualistically to climate change, the manifestations of their responses will be largely influenced by interactions with other organisms. Tractably dealing with complex interaction networks in the face of climate change will require an understanding of community dynamics and the degree to which biotic interactions influence species' behavior, physiology, and survival – and ultimately their footprint on the landscape. To improve our understanding of community-level responses to climate change, I explored amphibian response strategies from both a population- and community-level perspective and provided a critical evaluation of one of the primary methods for incorporating biotic interactions into predictive species distribution models. In Chapter 2, I evaluated amphibian species’ physiological constraints and the potential consequences of phenotypic plasticity as a first step to understanding their sensitivity, and ultimately, adaptive capacity to climate change. I experimentally quantified phenotypic plasticity in larval growth and development in three high elevation Anuran species (Anaxyrus boreas, Pseudacris regilla, and Rana cascadae) in response to projected climate warming scenarios for the Cascade Mountain Range. Warming initiated faster weight gain and accelerated larval growth rates in each of the species. However, any effort to achieve optimum body size (in both length and weight), while maintaining the necessary developmental trajectory under heat stress, was relatively unsuccessful. In Chapter 3, I tested the response strategies of the same three Anuran species to a different climate stressors, hydroperiod reduction (i.e. drought), and included the additional stress of interspecific competition. I found that competition exacerbated the effects of drying on competitively inferior species (Anaxyrus boreas and Pseudacris regilla) and that, in general, species responses were largely context-dependent. My results emphasize the importance of biotic interactions in predictions of species response to climate change. In Chapter 4, I provide a critical evaluation of standard methods for incorporating biotic interactions into predictive species distribution models. Most methods utilize observational data via species co-occurrences on the landscape to infer the role of biotic interactions in structuring species distributions. Results from a series of tests using two long-term amphibian co-occurrence datasets from Mt. Rainier National Park (Washington) and Mt. Hood (Oregon) show that the current best available methods are largely disconnected from community ecology theory and have yet to reconcile the complex dynamics within trophically-structured communities. My research aims to fill a critical knowledge gap in the connection between community dynamics and biogeography, with significant implications for conservation and management of a severely threatened taxonomic group. I highlight the significant challenges of estimating species response to climate change across multiple levels of taxonomic organization and spatio-temporal scales. Close

• 7. [Article] Water and Soil Management Practices to Enhance Plant Growth, Berry Development, and Fruit Quality of Northern Highbush Blueberry (Vaccinium corymbosum L.)

  Drought and mandatory water restrictions are limiting the availability of irrigation water in many important blueberry growing regions and new strategies are needed to maintain yield and fruit quality ...

  Citation × Citation Citation Abstract Copy Title: Water and Soil Management Practices to Enhance Plant Growth, Berry Development, and Fruit Quality of Northern Highbush Blueberry (Vaccinium corymbosum L.) Author: Almutairi, Khalid F. Drought and mandatory water restrictions are limiting the availability of irrigation water in many important blueberry growing regions and new strategies are needed to maintain yield and fruit quality with less water. Three potential options for reducing water use, including deficit irrigation, irrigation cut-offs, and crop thinning, were evaluated for 2 years in a mature planting of northern highbush blueberry (Vaccinium corymbosum L. ‘Elliott’). Treatments consisted of no thinning and 50% crop removal in combination with either full irrigation at 100% of estimated crop evapotranspiration (ETsubscript c]), deficit irrigation at 50% ET[subscript c] (applied for the entire growing season), or full irrigation with irrigation cut-off for 4–6 weeks during early or late stages of fruit development. Stem water potential was similar with full and deficit irrigation but, regardless of crop thinning, declined by 0.5–0.6 MPa when irrigation was cut-off early and by > 2.0 MPa when irrigation was cut-off late. In one or both years, the fruiting season was advanced with either deficit irrigation or late cut-off, whereas cutting off irrigation early delayed the season. Yield was not affected by deficit irrigation in plants with a full crop load but was reduced by an average of 35% when irrigation was cut-off late each year. Cutting off irrigation early likewise reduced yield, but only in the second year when the plants were not thinned; however, early cut-off also reduced fruit soluble solids and berry weight by 7% to 24%compared to full irrigation. Cutting off irrigation late produced the smallest and firmest fruit with the highest soluble solids and total acidity among the treatments, as well as the slowest rate of fruit loss in cold storage. Deficit irrigation had the least effect on fruit quality and, based on these results, appears to be the most viable option for maintaining yield with less water (2.5 ML·ha⁻¹ less water per season). A second study was conducted in a 7-year-old field of certified organic highbush blueberry. Two cultivars (‘Duke’ and ‘Liberty’) mulched with either porous polyethylene ground cover (“weed mat”) or yard debris compost topped with sawdust (sawdust+compost) and each fertilized with either feather meal or fish emulsion were evaluated. One-year-old fruiting laterals were randomly-selected at three heights (top, middle, and bottom) on the east and west side of the plants. Bud, flower, and fruit development were monitored through fruit harvest. There was relatively little effect of mulch type or fertilizer source on the measured variables. Fruit harvest occurred ≈8 d after the fruit were fully blue and ranged from 2-25 July 2012 and 26 June-3 July 2013 in ‘Duke’ and from 1-20 Aug. 2012 and 17 July-7 Aug. 2013 in ‘Liberty’. Proportionally more fruit buds occurred on middle laterals than upper and lower laterals. The dates of bud swell and bud break were not affected by cultivar or lateral position. ‘Duke’ and ‘Liberty’ produced 6-8 and 7-9 flowers/bud, respectively. Fruit set was high in both cultivars, averaging ≈95%. However, 13-18% and 29-38 % of the initial set fruit dropped in ’Duke’ and ‘Liberty’ in late May to early June. Fruit ripening was more uniform within clusters in ‘Duke’ than in ‘Liberty’, and average fruit size was similar among harvests in ‘Duke’ but decreased by 25-40% between the first and last harvest in ‘Liberty’. Fruit matured 3−5 d earlier on the east side of the canopy than on the west side. The results suggest that pruning proportionally more on the lower part of the canopy than on the upper part will result in larger fruit at harvest than uniform pruning throughout the bush. The final study was conducted to determine the potential of applying micronized elemental sulfur (S°) by chemigation through the drip system to reduce high soil pH in a new planting of ‘Duke’ blueberry. The S° was mixed with water and injected weekly for 2 months prior to planting, as well as 2 years after planting, atrates of 0, 50, 100 and 150 kg·ha⁻¹ per year, and was compared to the conventional practice of incorporating prilled S° into the soil prior to planting (two applications of 750 kg·ha⁻¹ each). Chemigation quickly reduced soil pH (0-10 cm) within a month from 6.6 with no S° to 6.1 with 50 kg·ha-1 S° and 5.8 with 100 or 150 kg·ha⁻¹ S°. The change was short-term, however, and by May of the following year, soil pH averaged 6.7, 6.5, 6.2, and 6.1 with each increasing rate of S° chemigation, respectively. The conventional treatment, in comparison, averaged 6.6 on the first date and 6.3 on the second date. In July of the following year, soil pH ranged from an average of 6.4 with no S° to 6.2 with 150 kg·ha⁻¹ S° and 5.5 with prilled S°. Soil pH declined thereafter to as low as 5.9 with additional S° chemigation and at lower depths (10-30 cm) was similar to the conventional treatment. None of the treatments had any effect on winter pruning weight in year 1 or on yield, berry weight, and plant dry weight in year 2. Chemigation with S° can be used to quickly reduce soil pH following planting and, therefore, may be a useful practice to correct high pH problems in established blueberry fields. However, it was less effective and more time consuming than applying prilled S° prior to planting. Title: Water and Soil Management Practices to Enhance Plant Growth, Berry Development, and Fruit Quality of Northern Highbush Blueberry (Vaccinium corymbosum L.) Author: Almutairi, Khalid F. Drought and mandatory water restrictions are limiting the availability of irrigation water in many important blueberry growing regions and new strategies are needed to maintain yield and fruit quality with less water. Three potential options for reducing water use, including deficit irrigation, irrigation cut-offs, and crop thinning, were evaluated for 2 years in a mature planting of northern highbush blueberry (Vaccinium corymbosum L. ‘Elliott’). Treatments consisted of no thinning and 50% crop removal in combination with either full irrigation at 100% of estimated crop evapotranspiration (ETsubscript c]), deficit irrigation at 50% ET[subscript c] (applied for the entire growing season), or full irrigation with irrigation cut-off for 4–6 weeks during early or late stages of fruit development. Stem water potential was similar with full and deficit irrigation but, regardless of crop thinning, declined by 0.5–0.6 MPa when irrigation was cut-off early and by > 2.0 MPa when irrigation was cut-off late. In one or both years, the fruiting season was advanced with either deficit irrigation or late cut-off, whereas cutting off irrigation early delayed the season. Yield was not affected by deficit irrigation in plants with a full crop load but was reduced by an average of 35% when irrigation was cut-off late each year. Cutting off irrigation early likewise reduced yield, but only in the second year when the plants were not thinned; however, early cut-off also reduced fruit soluble solids and berry weight by 7% to 24%compared to full irrigation. Cutting off irrigation late produced the smallest and firmest fruit with the highest soluble solids and total acidity among the treatments, as well as the slowest rate of fruit loss in cold storage. Deficit irrigation had the least effect on fruit quality and, based on these results, appears to be the most viable option for maintaining yield with less water (2.5 ML·ha⁻¹ less water per season). A second study was conducted in a 7-year-old field of certified organic highbush blueberry. Two cultivars (‘Duke’ and ‘Liberty’) mulched with either porous polyethylene ground cover (“weed mat”) or yard debris compost topped with sawdust (sawdust+compost) and each fertilized with either feather meal or fish emulsion were evaluated. One-year-old fruiting laterals were randomly-selected at three heights (top, middle, and bottom) on the east and west side of the plants. Bud, flower, and fruit development were monitored through fruit harvest. There was relatively little effect of mulch type or fertilizer source on the measured variables. Fruit harvest occurred ≈8 d after the fruit were fully blue and ranged from 2-25 July 2012 and 26 June-3 July 2013 in ‘Duke’ and from 1-20 Aug. 2012 and 17 July-7 Aug. 2013 in ‘Liberty’. Proportionally more fruit buds occurred on middle laterals than upper and lower laterals. The dates of bud swell and bud break were not affected by cultivar or lateral position. ‘Duke’ and ‘Liberty’ produced 6-8 and 7-9 flowers/bud, respectively. Fruit set was high in both cultivars, averaging ≈95%. However, 13-18% and 29-38 % of the initial set fruit dropped in ’Duke’ and ‘Liberty’ in late May to early June. Fruit ripening was more uniform within clusters in ‘Duke’ than in ‘Liberty’, and average fruit size was similar among harvests in ‘Duke’ but decreased by 25-40% between the first and last harvest in ‘Liberty’. Fruit matured 3−5 d earlier on the east side of the canopy than on the west side. The results suggest that pruning proportionally more on the lower part of the canopy than on the upper part will result in larger fruit at harvest than uniform pruning throughout the bush. The final study was conducted to determine the potential of applying micronized elemental sulfur (S°) by chemigation through the drip system to reduce high soil pH in a new planting of ‘Duke’ blueberry. The S° was mixed with water and injected weekly for 2 months prior to planting, as well as 2 years after planting, atrates of 0, 50, 100 and 150 kg·ha⁻¹ per year, and was compared to the conventional practice of incorporating prilled S° into the soil prior to planting (two applications of 750 kg·ha⁻¹ each). Chemigation quickly reduced soil pH (0-10 cm) within a month from 6.6 with no S° to 6.1 with 50 kg·ha-1 S° and 5.8 with 100 or 150 kg·ha⁻¹ S°. The change was short-term, however, and by May of the following year, soil pH averaged 6.7, 6.5, 6.2, and 6.1 with each increasing rate of S° chemigation, respectively. The conventional treatment, in comparison, averaged 6.6 on the first date and 6.3 on the second date. In July of the following year, soil pH ranged from an average of 6.4 with no S° to 6.2 with 150 kg·ha⁻¹ S° and 5.5 with prilled S°. Soil pH declined thereafter to as low as 5.9 with additional S° chemigation and at lower depths (10-30 cm) was similar to the conventional treatment. None of the treatments had any effect on winter pruning weight in year 1 or on yield, berry weight, and plant dry weight in year 2. Chemigation with S° can be used to quickly reduce soil pH following planting and, therefore, may be a useful practice to correct high pH problems in established blueberry fields. However, it was less effective and more time consuming than applying prilled S° prior to planting. Close