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Competition amplifies drought stress in forests across broad climatic and compositional gradients Categories: Publication; Tags: Data Visualization & Tools, Drought, Drought, Fire and Extreme Weather, Forests, Landscapes, All tags... National CASC, Science Tools For Managers, USA, aridity, competitive intensity, dendrochronology, drought severity, drought stress, forest density, forest growth, forest response, long-term experimental forests, Fewer tags Drivers of California’s changing wildfires: a state-of-the-knowledge synthesis Over the past four decades, annual area burned has increased significantly in California and across the western USA. This trend reflects a confluence of intersecting factors that affect wildfire regimes. It is correlated with increasing temperatures and atmospheric vapour pressure deficit. Anthropogenic climate change is the driver behind much of this change, in addition to influencing other climate-related factors, such as compression of the winter wet season. These climatic trends and associated increases in fire activity are projected to continue into the future. Additionally, factors related to the suppression of the Indigenous use of fire, aggressive fire suppression and, in some cases, changes in logging practices... Categories: Publication; Types: Citation Final Report: Informing and Evaluating Forest Management Strategies to Promote Drought Resistance Severe droughts cause widespread tree mortality and decreased growth in forests across the globe. Forest managers are seeking strategies to increase forest resistance (minimizing negative impacts during the drought) and resilience (maximizing recovery rates following drought). Limited experimental evidence suggests that forests with particular structural characteristics have greater capacity to resist change and or recover ecosystem function in the face of drought. However, the applicability of these results to practical forest conservation and management remains unclear. This project utilized an existing network of eight long-term, operational-scale, forest management experiments from Arizona to Maine to examine... Categories: Publication; Types: Citation, Report; Tags: Data Visualization & Tools, Drought, Drought, Fire and Extreme Weather, Forests, Landscapes, All tags... National CASC, Science Tools For Managers, drought, forest resistance, resilience, severe drought, tree mortality, Fewer tags Low stand density moderates growth declines during hot droughts in semi‐arid forests Abstract (from Journal of Applied Ecology): Increasing heat and aridity in coming decades is expected to negatively impact tree growth and threaten forest sustainability in dry areas. Maintaining low stand density has the potential to mitigate the negative effects of increasingly severe droughts by minimizing competitive intensity. However, the direct impact of stand density on the growing environment (i.e. soil moisture), and the specific drought metrics that best quantify that environment, are not well explored for any forest ecosystem. We examined the relationship of varying stand density (i.e. basal area) on soil moisture and stand‐level growth in a long‐term (multi‐decadal), ponderosa pine Pinus ponderosa,... Categories: Publication; Types: Citation Tree mortality response to drought-density interactions suggests opportunities to enhance drought resistance The future of dry forests around the world is uncertain given predictions that rising temperatures and enhanced aridity will increase drought-induced tree mortality. Using forest management and ecological restoration to reduce density and competition for water offers one of the few pathways that forests managers can potentially minimize drought-induced tree mortality. Competition for water during drought leads to elevated tree mortality in dense stands, although the influence of density on heat-induced stress and the durations of hot or dry conditions that most impact mortality remain unclear. Understanding how competition interacts with hot-drought stress is essential to recognize how, where and how much reducing... Categories: Publication; Types: Citation Are drought indices and climate data good indicators of ecologically relevant soil moisture dynamics in drylands? Droughts are disproportionately impacting global dryland regions where ecosystem health and function are tightly coupled to moisture availability. Drought severity is commonly estimated using algorithms such as the standardized precipitation-evapotranspiration index (SPEI), which can estimate climatic water balance impacts at various hydrologic scales by varying computational length. However, the performance of these metrics as indicators of soil moisture dynamics at ecologically relevant scales, across soil depths, and in consideration of broader scale ecohydrological processes, requires more attention. In this study, we tested components of climatic water balance, including SPEI and SPEI computation lengths, to... Categories: Publication; Types: Citation Dry forest decline is driven by both declining recruitment and increasing mortality in response to warm, dry conditions Aim Anticipating when and where changes in species' demographic rates will lead to range shifts in response to changing climate remains a major challenge. Despite evidence of increasing mortality in dry forests across the globe in response to drought and warming temperatures, the overall impacts on the distribution of dry forests are largely unknown because we lack comparable large-scale data on tree recruitment rates. Here, our aim was to develop range-wide population models for dry forest tree species (pinyon pine and juniper), quantifying both mortality and recruitment, to better understand where and under what conditions species range contractions are occurring. Location Western United States. Major taxa studied... Categories: Publication; Types: Citation Landscape‐scale restoration minimizes tree growth vulnerability to 21st century drought in a dry forest Abstract (from Ecological Applications): Increasing aridity is a challenge for forest managers and reducing stand density to minimize competition is a recognized strategy to mitigate drought impacts on growth. In many dry forests, the most widespread and common forest management programs currently being implemented focus on restoration of historical stand structures, primarily to minimize fire risk and enhance watershed function. The implications of these restoration projects for drought vulnerability are not well understood. Here, we examined how planned restoration treatments in the Four Forests Restoration Initiative, the largest forest restoration project in the United States, would alter landscape‐scale patterns... Categories: Publication; Types: Citation Landscape-scale forest restoration decreases vulnerability to drought mortality under climate change in southwest USA ponderosa forest Drought-induced tree mortality is predicted to increase in dry forests across the globe as future projections show hotter, drier climates. This could potentially result in large-scale tree die-offs, changes in species composition, and loss of forest ecosystem services, including carbon storage. While some studies have found that forest stands with greater basal areas (BA) have higher drought mortality, many have not evaluated the extent to which forests restored to lower densities via restoration activities affect drought mortality. The southwestern USA is particularly susceptible to tree mortality due to the predicted increases in temperature, drier soils, and forests with high density. Our objective was to evaluate... Categories: Publication; Types: Citation Where can managers effectively resist climate-driven ecological transformation in pinyon–juniper woodlands of the US Southwest? Pinyon–juniper (PJ) woodlands are an important component of dryland ecosystems across the US West and are potentially susceptible to ecological transformation. However, predicting woodland futures is complicated by species-specific strategies for persisting and reproducing under drought conditions, uncertainty in future climate, and limitations to inferring demographic rates from forest inventory data. Here, we leverage new demographic models to quantify how climate change is expected to alter population demographics in five PJ tree species in the US West and place our results in the context of a climate adaptation framework to resist, accept, or direct ecological transformation. Two of five study species, Pinus... Categories: Publication; Types: Citation The aboveground and belowground growth characteristics of juvenile conifers in the southwestern United States Juvenile tree survival will play an important role in the persistence of coniferous forests and woodlands in the southwestern United States (SWUS). Vulnerability to climatic and environmental stress declines as trees grow, such that larger, more deeply rooted juveniles are less likely to experience mortality. It is unclear how juvenile conifers partition the aboveground and belowground components of early growth, if growth differs between species and ecosystem types, and what environmental factors influence juvenile carbon allocation above- or belowground. We developed a novel data set for four juvenile conifer groups (junipers, piñon pines, ponderosa pines, firs; 1121 juveniles sampled, 221 destructively) in three... Categories: Publication; Types: Citation Patterns of Big Sagebrush Plant Community Composition and Stand Structure in the Western United States Abstract (from ScienceDirect): Big sagebrush (Artemisia tridentata Nutt.) plant communities are found in western North America and comprise a mix of shrubs, forbs, and grasses. Climate, topography, and soil water availability are important factors that shape big sagebrush stand structure and plant community composition; however, most studies have focused on understanding these relationships at sites in a small portion of the big sagebrush region. Our goal was to characterize detailed stand structure and plant composition patterns and identify environmental variables related to those patterns by sampling 15 sites distributed across the western United States. In each site, we characterized stand structure at the individual... Categories: Publication; Types: Citation; Tags: Data Visualization & Tools, North Central CASC, Science Tools For Managers Density-dependent vulnerability of forest ecosystems to drought Abstract (from http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12847/full): Climate models predict increasing drought intensity and frequency for many regions, which may have negative consequences for tree recruitment, growth and mortality, as well as forest ecosystem services. Furthermore, practical strategies for minimizing vulnerability to drought are limited. Tree population density, a metric of tree abundance in a given area, is a primary driver of competitive intensity among trees, which influences tree growth and mortality. Manipulating tree population density may be a mechanism for moderating drought-induced stress and growth reductions, although the relationship between tree population density and... Categories: Publication; Types: Citation; Tags: Data Visualization & Tools, Drought, Drought, Fire and Extreme Weather, Forests, Landscapes, All tags... National CASC, Pinus ponderosa, Pinus resinosa, Science Tools For Managers, climate change adaptation, drought impacts, ecosystem services, semi-arid forests, temperate forests, thinning, tree population densisty, Fewer tags Climate change reduces extent of temperate drylands and intensifies drought in deep soils Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. While drylands as a whole are expected to increase in extent and aridity in coming decades, temperature and precipitation forecasts vary by latitude and geographic region suggesting different trajectories for tropical, subtropical, and temperate drylands. Uncertainty in the future of tropical and subtropical drylands is well constrained, whereas soil moisture and ecological droughts, which drive vegetation productivity and composition, remain poorly understood in temperate drylands. Here we show that, over the twenty first century, temperate drylands may contract by a third, primarily converting to subtropical drylands,... Categories: Publication; Types: Citation Future soil moisture and temperature extremes imply expanding suitability for rainfed agriculture in temperate drylands Abstract The distribution of rainfed agriculture, which accounts for approximately ¾ of global croplands, is expected to respond to climate change and human population growth and these responses may be especially pronounced in water limited areas. Because the environmental conditions that support rainfed agriculture are determined by climate, weather, and soil conditions that affect overall and transient water availability, predicting this response has proven difficult, especially in temperate regions that support much of the world’s agriculture. Here, we show that suitability to support rainfed agriculture in temperate dryland climates can be effectively represented by just two daily environmental variables: moist... Categories: Publication; Types: Citation Plant Production Responses to Precipitation Differ Along an Elevation Gradient and Are Enhanced Under Extremes Categories: Publication; Types: Citation; Tags: Drought, Drought, Fire and Extreme Weather, National CASC, biomass, climate change, All tags... drought, grassland, net primary production, remote sensing, southwestern USA, Fewer tags Assessing plant production responses to climate across water-limited regions using Google Earth Engine Categories: Publication; Tags: Climate change, Drought, Drought, Drought, Fire and Extreme Weather, Dryland, All tags... Landsat remote sensing time series, National CASC, Net primary production, Soil-adjusted vegetation index (SAVI), Southwestern U.S., Standardized precipitation evapotranspiration index (SPEI), Fewer tags Understanding the future of big sagebrush regeneration: challenges of projecting complex ecological processes Regeneration is an essential demographic step that affects plant population persistence, recovery after disturbances, and potential migration to track suitable climate conditions. Challenges of restoring big sagebrush (Artemisia tridentata) after disturbances including fire-invasive annual grass interactions exemplify the need to understand the complex regeneration processes of this long-lived, woody species that is widespread across the semiarid western U.S. Projected 21st century climate change is expected to increase drought risks and intensify restoration challenges. A detailed understanding of regeneration will be crucial for developing management frameworks for the big sagebrush region in the 21st century.... Categories: Publication; Types: Citation Unfamiliar Territory: Emerging Themes for Ecological Drought Research and Management Abstract (from One Earth): Novel forms of drought are emerging globally, due to climate change, shifting teleconnection patterns, expanding human water use, and a history of human influence on the environment that increases the probability of transformational ecological impacts. These costly ecological impacts cascade to human communities, and understanding this changing drought landscape is one of today’s grand challenges. By using a modified horizon-scanning approach that integrated scientists, managers, and decision-makers, we identified the emerging issues in ecological drought that represent key challenges to timely and effective responses. Here we review the themes that most urgently need attention, including... Categories: Publication; Types: Citation Quantifying the demographic vulnerabilities of dry woodlands to climate and competition using range-wide monitoring data Climate change is expected to alter the distribution and abundance of tree species, impacting ecosystem structure and function. Yet, anticipating where this will occur is often hampered by a lack of understanding of how demographic rates, most notably recruitment, vary in response to climate and competition across a species range. Using large-scale monitoring data on two dry woodland tree species (Pinus edulis and Juniperus osteosperma), we develop an approach to infer recruitment, survival, and growth of both species across their range. In doing so, we account for ecological and statistical dependencies inherent in large-scale monitoring data. We find that warming and drying conditions generally lead to declines... 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