Invasive annual grasses are a growing threat to sagebrush steppe environments, affecting wildlife habitat by shortening fire return intervals and shifting composition of plant communities. Greater sage-grouse (Centrocercus urophasianus B.) rely on sagebrush steppe plants for forage and cover and are therefore vulnerable to impacts of invasive annual grasses. Pre-emergent herbicides such as indaziflam control annual grasses like cheatgrass (Bromus tectorum L.) and Japanese brome (Bromus japonicus Thunb.) and are increasingly used in natural areas, but effects of this tool on sage-grouse have not been evaluated. We contrasted greater sage-grouse habitat use between indaziflam-treated and untreated sagebrush steppe moderately invaded (15–30% cover) by annual bromes in south-central Idaho. To estimate relative habitat use, we conducted grouse pellet surveys along 50-m transects (n = 48 transects) during the summer brood-rearing period in 2023 and 2024, 3-5 years after treatment. We also conducted plant surveys along pellet transects, focusing on dietary forbs preferred by sage-grouse. We found that treated transects had lower annual Bromus spp. cover, annual preferred forb cover, and annual preferred forb Shannon diversity relative to untreated transects. Further, treated transects were associated with higher bare ground cover, as well as increased perennial preferred forb cover 4-5 years after treatment. Other plant community characteristics, including total cover of preferred forbs, were similar between treated and untreated transects. Notably, sage-grouse habitat use was twice as high on indaziflam-treated compared to untreated transects. These results suggest that indaziflam application in cheatgrass-invaded sagebrush steppe with relatively intact native plant communities may improve habitat conditions for sage-grouse despite potential decrements in annual forbs.
In the western United States, riparian zones dominated by willows (Salix spp.) provide a disproportional number of ecosystem services, including hotspots of biological diversity and significant carbon sinks. Nondestructive approaches to determine aboveground biomass of willows in riparian zones are a valuable means of ascertaining ecological function and condition, shifts in structural diversity, as well as the quantification of carbon stocks and rates of sequestration. We developed equations for estimating aboveground biomass of common tall willow species in the Northern Range of Yellowstone National Park. Strong correlations exist between aboveground biomass and easily measured variables of plant height, crown diameter, crown area, and crown volume (R2 = 0.81–0.97). With increasing plant size, biomass accumulation is exponential rather than linear. This suggests that average increases in plant heights over time (a linear rate of increase) do not accurately describe changes in crown volume or biomass; variables that strongly correlate with structural diversity of riparian communities. Coupling biomass estimates of individual willows with willow density we found strong effects of large ungulate browsing on these highly palatable species. Aboveground willow biomass ranged from <0.04 Mg · ha−1 in sites heavily grazed by bison (Bison bison) and up to 211 Mg · ha−1 in ungrazed riparian zones.
Fire interacts with ecosystem carbon in North American fire-grazing rangelands through processes that span chemical forms, soil depths, and temporal horizons. We synthesize empirical evidence on fire-driven carbon redistribution across the continental region where frequent fire and bison grazing historically co-occurred. Across these rangelands, temperate grasses allocate roughly 75–80% of biomass belowground, outside the combustion zone. Herbaceous aboveground biomass typically recovers within one to three growing seasons. Incomplete combustion produces pyrogenic carbon (PyC) amounting to ∼12% of the carbon emitted by fire. The stable component of that PyC persists in soil on centennial to millennial timescales. Frequent burning can reduce bulk soil organic carbon relative to fire exclusion, especially in dry systems, while shifting carbon inputs toward pyrogenic material. Across the Great Plains, shorter modeled fire intervals are associated with a larger mineral-associated fraction and a smaller particulate fraction, whereas the pyrogenic fraction changes little. Where fire is excluded, woody plant encroachment shifts a larger share of ecosystem carbon into aboveground biomass exposed to fire, drought, and dieback, while altering hydrologic function, biodiversity, and resilience to disturbance. The fire-grazing interaction distributes combustion and recovery across a shifting patch mosaic in which litter retention, grazing pressure, and belowground carbon inputs vary among patches. Carbon accounting frameworks that measure only stock size can mistake the carbon vulnerability created by fire suppression for carbon gain, inadvertently penalizing disturbance that sustains persistent soil carbon in these systems.
Mediterranean rangelands provide a substantial part of the annual diet of small ruminants in the extensive livestock systems of southern Europe. Woody vegetation, plant diversity and strong seasonal and structural heterogeneity complicate the estimation of the feeding value of these pastures. Conventional approaches based on botanical composition or herbaceous-layer indicators provide only a partial assessment of feed resource diversity, quality and nutritional role. We propose an alternative approach where we build a classification, based on near-infrared spectroscopy applied to 304 samples representative of the resources selected by sheep and goats in Mediterranean rangelands. Bite types were identified through behavioural observations and sampled across three sites in southern France during spring and autumn over two years. Spectra from dried and ground samples were pretreated and analysed using principal component analysis followed by hierarchical clustering. The resulting clusters separated resources according to plant organs and displayed consistent chemical and structural characteristics. Together, they formed a gradient ranging from protein-rich and highly digestible young organs, to fibre-rich and structurally dense resources. The classification was evaluated through cluster stability analyses, spatio-temporal cross-validations and projection of an independent dataset, complemented by qualitative assessment from farmers and technical advisors. Results revealed stable cluster cores and biologically-meaningful transition zones, particularly for reproductive organs such as grass ears and legume pods. Projection of the independent dataset showed strong overlap with the reference spectral space, supporting transferability beyond the initial sampling conditions. This approach provides an operational framework for integrating pastoral resource diversity into rangeland assessment and feeding management.
Successful rangeland revegetation on western rangelands can be challenging with natural and human-related influences. Defoliation from a wide range of vertebrate and invertebrate grazers can reduce seedling growth and increase plant mortality, thereby impeding restoration efforts. Understanding how herbivory can impede plant establishment and growth may help predict restoration outcomes and create effective solutions for rangeland restoration. Bottlebrush squirreltail (Elymus elymoides (Raf.) Swezey), a native perennial grass species often used in seed mixes, stabilizes soils, provides quality forage, and competes with annual plants. The purpose of this study was to identify the impact of herbivory on bottlebrush squirreltail seedling damage and mortality. This study was conducted on the Utah Test and Training Range (UTTR) in western Utah, USA, tracking herbivory, seedling emergence, and timing and cause of seedling death. We placed cameras in 28 randomly placed plots arranged in a randomized split-plot design with fenced and unfenced plots and seeded with two rows of bottlebrush squirreltail. We tracked individual seedlings and recorded their condition (alive, dead, grazed or damaged), comparing establishment and survival between fenced and unfenced plots. Seed predators reduced initial seedling establishment in unfenced plots by four times ( P = 0.0 0 02). Seedlings were seven times more likely to survive in fenced vs. unfenced plots. Of total seedling mortality, 73.6% of seedling death was caused by herbivory from black-tailed jackrabbit (Lepus californicus), invertebrate herbivores, and Botta's pocket gopher (Thomomys bottae). Strategies to mitigate the effect of herbivores should be considered to increase seeded plant establishment during restoration efforts. These results highlight the broader need for restoration projects in arid and semi-arid ecosystems to account for herbivore communities when planning seeding projects, as early-stage herbivory can strongly limit plant establishment across many species and ecosystems. (c) 2026 The Society for Range Management. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
