Research and Publications
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Using shrub, grass, and forb species from six locations in the western Great Basin, North America, we compared establishment, productivity, reproduction, phenology, and resistance to invaders for experimental communities with either sympatric or allopatric population associations. Each community type was planted with six taxa in outdoor mesocosms, measured over three growing seasons, and invaded with the annual grass Bromus tectorum in the final season. For most populations, the allopatric or sympatric status of neighbors was not important. However, in some cases, it was beneficial for some species from some locations to be planted with allopatric neighbors, while others benefited from sympatric neighbors, and some of these responses had large effects. For instance, the Elymus population that benefited the most from allopatry grew 50% larger with allopatric neighbors than in single origin mesocosms. This response affected invasion resistance, as B. tectorum biomass was strongly affected by productivity and phenology of Elymus spp., as well as Poa secunda. Our results demonstrate that, while community composition can affect plant performance in semi-arid plant communities, assembling communities from sympatric populations is not sufficient to ensure high productivity and invasion resistance. Instead, we observed an idiosyncratic interaction between sampling effects and evolutionary history, with the potential for seed source of individual populations to have community-level effects.
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We found that there were large proportions of non-significant responses among all categories combined, with roughly half or more of all responses non-significant (48 percent for wildlife, 60 percent for vegetation-environmental), comparable to other recent systematic reviews of pinyon-juniper treatment effects. However, we also found that when there were significant responses, some important trends potentially emerged. Important undesirable outcomes included far more positive than negative responses of exotic grass and forb abundance among nearly all treatment types. Cutting treatments were also more likely to decrease biocrust cover and microbial activity. Potentially beneficial outcomes included mostly positive responses among sagebrush obligate species, including more positive than negative responses for mule deer and sage-grouse. Some treatment types (for example, mastication) also resulted in more positive than negative responses for native grasses and forbs (although, non-significant responses were the majority). We also highlighted many limitations of this review, including how responses often come from few studies, and how some response-treatment category combinations lack adequate response data. Moreover, the existing research is often insufficient to address many key questions about treatment effects, largely owing to short time-scales and limited spatial extents of observations, which do not match the size of treatments being implemented by land managers, nor capture long-term, post-treatment ecological dynamics. We also identify a lack of research that addresses key interactions that could undermine restoration objectives, including potential effects of climate change and grazing on post-treatment environments. Thus, we emphasize the importance of integrating these factors into future pinyon-juniper treatment research, and we stress the need for use of monitoring programs and research studies that partake in data collection and analysis over long durations and broad spatial scales.
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More frequent, larger, and severe wildfires necessitate greater resources for fire-prevention, fire-suppression, and postfire restoration activities, while decreasing critical ecosystem services, economic and recreational opportunities, and cultural traditions. Increased flexibility and better prioritization of management activities based on ecological needs, including commitment to long-term prefire and postfire management, are needed to achieve notable reductions in uncharacteristic wildfire activity and associated negative impacts. Collaboration and partnerships across jurisdictional boundaries, agencies, and disciplines can improve consistency in sagebrush-management approaches and thereby contribute to this effort. Here, we provide a synthesis on sagebrush wildfire trends and the impacts of uncharacteristic fire regimes on sagebrush plant communities, dependent wildlife species, fire-suppression costs, and ecosystem services. We also provide an overview of wildland fire coordination efforts among federal, state, and tribal entities.
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The 2020 Resources Planning Act (RPA) Assessment summarizes findings about the status, trends, and projected future of the Nation’s forests and rangelands and the renewable resources that they provide. The 2020 RPA Assessment specifically focuses on the effects of both socioeconomic and climatic change on the U.S. land base, disturbance, forests, forest product markets, rangelands, water, biodiversity, and outdoor recreation. Differing assumptions about population and economic growth, land use change, and global climate change from 2020 to 2070 largely influence the outlook for U.S. renewable resources. Many of the key themes from the 2010 RPA Assessment cycle remain relevant, although new data and technologies allow for deeper and wider investigation. Land development will continue to threaten the integrity of forest and rangeland ecosystems. In addition, the combination and interaction of socioeconomic change, climate change, and the associated shifts in disturbances will strain natural resources and lead to increasing management and resource allocation challenges. At the same time, land management and adoption of conservation measures can reduce pressure on natural resources. The RPA Assessment findings and associated data can be useful to resource managers and policymakers as they develop strategies to sustain natural resources.
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By connecting high-resolution estimates of fine fuel to climatic, biophysical and land-use factors, wildfire exposure, and a natural resource value at risk, we provide a pro-active and adaptive framework for fire risk management within highly variable and rapidly changing dryland landscapes.
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Wildfires burned more area on non-forested lands than forested lands over the past 20 years. This was true for all land ownerships in CONUS and the western US. Burned area increased over the 20-year time period for both non-forest and forest. Across CONUS, annual area burned was higher on non-forest than forests for 14 of the past 21 years (Fig. 1), and total area burned was almost 3,000,000 ha more in non-forest than in forest. For the western US, total burned area was almost 1,500,000 ha more in non-forest than in forest. From a federal agency perspective, approximately 74% of the burned area on Department of the Interior (DOI) lands occurred in non-forest and 78% of the burned area on US Forest Service (FS) lands occurred in the forest.
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We synthesized restoration techniques and their effectiveness in the Mojave and western Sonoran Desert, provide estimated costs of candidate techniques, and anticipate future research needs for effective restoration in changing climates and environments. Over 50 published studies in the Mojave and western Sonoran Desert demonstrate that restoration can improve soil features (e.g., biocrusts), increase cover of native perennial and annual plants, enhance native seed retention and seed banks, and reduce risk of fires to conserve mature shrubland habitat. We placed restoration techniques into three categories: restoration of site environments, revegetation, and management actions to limit further disturbance and encourage recovery. Within these categories, 11 major restoration techniques (and their variations) were evaluated by at least one published study and range from geomorphic (e.g., reestablishing natural topographic patterns) and abiotic structural treatments (e.g., vertical mulching) to active revegetation (e.g., outplanting, seeding).
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Our systematic review returned a sample of 222 publications that met these criteria, with an increase in wilderness fire science over time. Studies largely occurred in the USA and were concentrated in a relatively small number of protected areas, particularly in the Northern Rocky Mountains. As a result, this sample of wilderness fire science is highly skewed toward areas of temperate mixed-conifer forests and historical mixed-severity fire regimes. Common principal subjects of publications included fire effects (44%), wilderness fire management (18%), or fire regimes (17%), and studies tended to focus on vegetation, disturbance, or wilderness management as response variables.
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The West Coast both experiences the largest smoke exposures and contributes most to the burden of smoke PM2.5 in the western US. Applying prescribed burns on the coast yields large benefits for the West, while doing so in other states has relatively smaller impacts. Larger prescribed burns may reduce smoke impacts from future large wildfires, but few such burns have occurred in key areas.