Plant Functional Groups and Species Contribute to Ecological Resilience a Decade After Woodland Expansion Treatments

Woody plant expansions are altering ecosystem structure and function, as well as fire regimes, around the globe. Tree-reduction treatments are widely implemented in expanding woodlands to reduce fuel loads, increase ecological resilience, and improve habitat, but few studies have measured treatment outcomes over long timescales or large geographic areas. The Sagebrush Treatment Evaluation Project (SageSTEP) evaluated the ecological effects of prescribed fire and cut-and-leave treatments in sagebrush communities experiencing tree expansion in North American cold desert shrublands. We used 10 yr of data from the SageSTEP network to test how treatments interacted with pre-treatment tree dominance, soil climate, and time since treatment to affect plant functional groups and dominant species. Non-sprouting shrub (Artemisia spp.), sprouting shrub, perennial graminoid, and annual grass responses depended on tree dominance and soil climate, and responses were related to the dominant species\u27 life-history traits. Sites with warm and dry soils showed increased perennial graminoid but reduced Artemisia shrub cover across the tree dominance gradient after prescribed burning, while sites with cool and moist soils showed favorable post-burn responses for both functional types, particularly at low to moderate tree dominance. Cut-and-leave treatments sustained or increased native perennial plant functional groups and experienced smaller increases in exotic annual plants in both soil climates across the tree dominance gradient. Both treatments reduced biocrust cover. Selecting appropriate tree-reduction treatments to achieve desired long-term outcomes requires consideration of dominant species, site environmental conditions, and the degree of woodland expansion. Careful selection of management treatments will reduce the likelihood of undesirable consequences to the ecosystem

Invasive annual grasses—Reenvisioning approaches in a changing climate

For nearly a century, invasive annual grasses have increasingly impacted terrestrial ecosystems across the western United States. Weather variability associated with climate change and increased atmospheric carbon dioxide (CO2) are making even more difficult the challenges of managing invasive annual grasses. As part of a special issue on climate change impacts on soil and water conservation, the topic of invasive annual grasses is being addressed by scientists at the USDA Agricultural Research Service to emphasize the need for additional research and future studies that build on current knowledge and account for (extreme) changes in abiotic and biotic conditions. Much research has focused on understanding the mechanisms underlying annual grass invasion, as well as assessing patterns and responses from a wide range of disturbances and management approaches. Weather extremes and the increasing occurrences of wildfire are contributing to the complexity of the problem. In broad terms, invasive annual grass management, including restoration, must be proactive to consider human values and ecosystem resiliency. Models capable of synthesizing vast amounts of diverse information are necessary for creating trajectories that could result in the establishment of perennial systems. Organization and collaboration are needed across the research community and with land managers to strategically develop and implement practices that limit invasive annual grasses. In the future, research will need to address invasive annual grasses in an adaptive integrated weed management (AIWM) framework that utilizes models and accounts for climate change that is resulting in altered/new approaches to management and restoration

Enhancing wind erosion monitoring and assessment for U.S. rangelands

Wind erosion is a major resource concern for rangeland managers because it can impact soil health, ecosystem structure and function, hydrologic processes, agricultural production, and air quality. Despite its significance, little is known about which landscapes are eroding, by how much, and when. The National Wind Erosion Research Network was established in 2014 to develop tools for monitoring and assessing wind erosion and dust emissions across the United States. The Network, currently consisting of 13 sites, creates opportunities to enhance existing rangeland soil, vegetation, and air quality monitoring programs. Decision-support tools developed by the Network will improve the prediction and management of wind erosion across rangeland ecosystems. © 2017 The Author(s)The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Agricultural Research Service Weed Science Research: Past, Present, and Future

The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed-crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America\u27s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency\u27s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being

Climate Change Impacts on Net Ecosystem Productivity in a Subtropical Shrubland of Northwestern México

The sensitivity of semiarid ecosystems to climate change is not well understood due to competing effects of soil and plantâ mediated carbon fluxes. Limited observations of net ecosystem productivity (NEP) under rising air temperature and CO2 and altered precipitation regimes also hinder climate change assessments. A promising avenue for addressing this challenge is through the application of numerical models. In this work, we combine a mechanistic ecohydrological model and a soil carbon model to simulate soil and plant processes in a subtropical shrubland of northwest México. Due to the influence of the North American monsoon, the site exhibits net carbon losses early in the summer and net carbon gains during the photosynthetically active season. After building confidence in the simulations through comparisons with eddy covariance flux data, we conduct a series of climate change experiments for nearâ future (2030â 2045) scenarios that test the impact of meteorological changes and CO2 fertilization relative to historical conditions (1990â 2005). Results indicate that reductions in NEP arising from warmer conditions are effectively offset by gains in NEP due to the impact of higher CO2 on water use efficiency. For cases with higher summer rainfall and CO2 fertilization, climate change impacts lead to an increase of ~25% in NEP relative to historical conditions (mean of 66 g C mâ 2). Net primary production and soil respiration derived from decomposition are shown to be important processes that interact to control NEP and, given the role of semiarid ecosystems in the global carbon budget, deserve attention in future simulation efforts of ecosystem fluxes.Key PointsModel simulation accurately captured the seasonality of vegetation activityNet ecosystem productivity decreased under reduced summer rainfall and increased temperature scenariosElevated CO2 scenarios offset the negative impacts of meteorological conditionsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142969/1/jgrg20992_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142969/2/jgrg20992.pd

Roots under attack : Contrasting plant responses to below- and aboveground insect herbivory

The distinctive ecology of root herbivores, the complexity and diversity of root-microbe interactions, and the physical nature of the soil matrix mean that plant responses to root herbivory extrapolate poorly from our understanding of responses to aboveground herbivores. For example, root attack induces different changes in phytohormones to those in damaged leaves, including a lower but more potent burst of jasmonates in several plant species. Root secondary metabolite responses also differ markedly, although patterns between roots and shoots are harder to discern. Root defences must therefore be investigated in their own ecophysiological and evolutionary context, specifically one which incorporates root microbial symbionts and antagonists, if we are to better understand the battle between plants and their hidden herbivores