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

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

Direct effects of soil amendments on field emergence and growth of the invasive annual grass Bromus tectorum L. and the native perennial grass Hilaria jamesii (Torr.) Benth

Bromus tectorum L. is a non-native, annual grass that has invaded western North America. In SE Utah, B. tectorum generally occurs in grasslands dominated by the native perennial grass, Hilaria jamesii (Torr.) Benth. and rarely where the natives Stipa hymenoides Roem. and Schult. and S. comata Trin. & Rupr. are dominant. This patchy invasion is likely due to differences in soil chemistry. Previous laboratory experiments investigated using soil amendments that would allow B. tectorum to germinate but would reduce B. tectorum emergence without affecting H. jamesii. For this study we selected the most successful treatments (CaCl2, MgCl2, NaCl and zeolite) from a previous laboratory study and applied them in the field in two different years at B. tectorum-dominated field sites. All amendments except the lowest level of CaCl2 and zeolite negatively affected B. tectorum emergence and/or biomass. No amendments negatively affected the biomass of H. jamesii but NaCl reduced emergence. Amendment effectiveness depended on year of application and the length of time since application. The medium concentration of zeolite had the strongest negative effect on B. tectorum with little effect on H. jamesii. We conducted a laboratory experiment to determine why zeolite was effective and found it released large amounts of Na+, adsorbed Ca2+, and increased Zn2+, Fe2+, Mn2+, Cu2+, exchangeable Mg2+, exchangeable K, and NH+4 in the soil. Our results suggest several possible amendments to control B. tectorum. However, variability in effectiveness due to abiotic factors such as precipitation and soil type must be accounted for when establishing management plans

Building a Teaching Technology Toolbox for Rangeland Ecology

The world is becoming more connected and integrated with technology by the minute, and the academic world is no exception. Students are of the Digital Age, and faculty struggle to keep up. Despite the technological literacy of students, schools and universities still provide the scientific background and applicable tools for rangeland ecology and management careers. Thus, instructors can use technology and online resources as learning tools to develop students’ understanding of scientific fundamentals, core competences, and practical skills necessary for the workplace. Here, we discuss the reasons to use technology and online resources, provide examples applicable to rangeland ecology and management, and discuss considerations when employing technology in teaching. The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform March 202

The Effect of Seeding Treatments and Climate on Fire Regimes in Wyoming Sagebrush Steppe

Wildfire size and frequency have increased in the western United States since the 1950s, but it is unclear how seeding treatments have altered fire regimes in arid steppe systems. We analyzed how the number of fires since 1955 and the fire return interval and frequency between 1995 and 2015 responded to seeding treatments, anthropogenic features, and abiotic landscape variables in Wyoming big sagebrush ecosystems. Arid sites had more fires than mesic sites and fire return intervals were shortest on locations first treated between 1975 and 2000. Sites drill seeded before the most recent fire had fewer, less frequent fires with longer fire return intervals (15–20 years) than aerially seeded sites (intervals of 5–8 years). The response of fire regime variables at unseeded sites fell between those of aerial and drill seeding. Increased moisture availability resulted in decreased fire frequency between 1994 and 2014 and the total number of fires since 1955 on sites with unseeded and aerially pre-fire seeding, but fire regimes did not change when drill seeded. Greater annual grass biomass likely contributed to frequent fires in the arid region. In Wyoming big sagebrush steppe, drill seeding treatments reduced wildfire risk relative to aerial seeded or unseeded sites

Data Paper. Data Paper

<h2>File List</h2><div> <p><a href="Mass_volume_data.txt">Mass_volume_data.txt</a> (MD5: 8cd6a810d1b410b6aea55ea8e6406818)</p> <p><a href="Allometry_Treatment_Comparisons.txt">Allometry_Treatment_Comparisons.txt</a> (MD5: f87e4c2c18f924639e348074ffcd8598)</p> <p><a href="Allometry_Best_Estimates.txt">Allometry_Best_Estimates.txt</a> (MD5: dff313b5c826596e872dfd991175faaa)</p> </div><h2>Description</h2><div> <p>Known allometric relationships between aboveground plant biomass and canopy volume allow standing biomass and net primary productivity (NPP) to be estimated non-destructively. Canopy volume–aboveground biomass relationships are published for many ecosystems, but not for most desert species. It is also unknown if elevated atmospheric carbon dioxide [CO₂] affects canopy volume–aboveground biomass relationships in desert perennials, limiting efforts to model NPP in an elevated CO₂ environment. We measured canopy volume and aboveground biomass for perennial plants in the Mojave Desert, USA, at the Nevada Desert FACE Facility (NDFF): four species before treatment and 22 species after 10 years (1997–2007) of elevated CO₂. Canopy volume to aboveground biomass allometry was estimated for each of the nine most common species individually; the remaining 13 species and unidentified dead shrubs combined to form a single “other” group. The resulting slopes and intercepts, which were estimated using a robust version of major axis regression, were compared across treatments and time points. None of the species had altered allometry in elevated CO₂ compared to ambient CO₂ treatments, nor did the relationships change over time. Data for each species were therefore combined across treatments and time points to provide the best available predictive equations relating canopy volume and aboveground biomass. The data set contains the canopy volume and aboveground biomass for all 3702 individual plants that were measured. We provide the regression coefficients relating canopy volume to aboveground biomass for both treatment and time comparisons and a single equation that predicts aboveground biomass from canopy volume for each species group. Our results suggest that grasses, forbs, and cacti may increase more rapidly in canopy volume than aboveground biomass, resulting in more shallow slopes compared to woody shrubs. The most notable limitation of this data set is that the maximum plant size at this site may be smaller than at other locations with the same species. The canopy volume to aboveground biomass equations could be improved by adding data from additional locations. Our results suggest that aboveground biomass for desert perennial plants in elevated CO₂ conditions may be reasonably estimated from the allometry of plants under ambient CO₂.</p> <p> <i>Key words</i>: Acamptopappus;<i> allometry; </i>Ambrosia;<i> aridland; climate change; </i>Ephedra; Krameria; Larrea; Lycium; Pleuraphis; Psorothamnus;<i> production.</i></p> </div

Environmental Influences on Density and Height Growth of Natural Ponderosa Pine Regeneration following Wildfires

Over the past century the size and severity of wildfires, as well as post-fire recovery processes (e.g., seedling establishment), have been altered from historical levels due to management policies and changing climate. Tree seedling establishment and growth drive future overstory tree dynamics after wildfire. Post-fire tree regeneration can be highly variable depending on burn severity, pre-fire forest condition, tree regeneration strategies, and climate; however, few studies have examined how different abiotic and biotic factors impact seedling density and growth and the interactions among those factors. We measured seedling density and height growth in the period 2015–2016 on three wildfires that burned in ponderosa pine (Pinus ponderosa) forests in the period 2000–2007 across broad environmental and burn severity gradients. Using a non-parametric multiplicative regression model, we found that downed woody fuel load, duff depth, and fall precipitation best explained variation in seedling density, while the distance to nearest seed tree, a soil productivity index, duff depth, and spring precipitation as snow best explained seedling height growth. Overall, results highlight the importance of burn severity and post-fire climate in tree regeneration, although the primary factors influencing seedling density and height growth vary. Drier conditions and changes to precipitation seasonality have the potential to influence tree establishment, survival, and growth in post-fire environments, which could lead to significant impacts for long-term forest recovery

A strategic plan for future USDA- Agricultural Research Service erosion research and model development

Soil erosion is a natural process, and the erosion potential of a site is the result of complex interactions among soil, vegetation, topographic position, land use and management, and climate. Soil erosion occurs when aeolian and hydrologic processes exceed a soil’s inherent resistance to these forces. Soil erosion was recognized as a significant problem at both local and national scales in the United States in the 1920s; by 1935 soil erosion was considered a national disaster, covering over one-half of the country (Sampson and Weyl 1918; Weaver 1935), and is still a concern with 21% of the western United States degraded and vulnerable to accelerated soil erosion (Herrick et al. 2010; Weltz et al. 2014a; Duniway et al. 2019). In 1995, it was estimated that 4 × 109 t (4.4 × 109 tn) of soil was lost from US cropland (Pimentel et al. 1995). The most vulnerable areas for soil movement and thus erosion occur where annual precipitation is 100 to 400 mm y–1 (4 to 16 in yr–1), which limits soil moisture available to sustain plant growth. Anthropogenic-driven dust emissions have dramatically increased across the globe (Webb and Pierre 2018) and in the United States (Neff et al. 2008) over last several decades. On-site and off-site costs associated with wind erosion exceeds US$8 billion y–1 Huszar and Piper 1986; USDA 1993). The combined off-site and on-site costs of erosion from agriculture in the United States is estimated to be about US$44 billion y–1, or about US$100 ha–1 (US$40 ac–1) of cropland and pasture (Pimentel et al. 1995), and US$44.5 billion in the European Union (Montanarella 2007). Cropland and livestock production contribute US$132.8 billion or 1% of the US gross domestic product. Erosion increases production costs by ~25% each year