Age structure and self-thinning indicate the development of plant species and their adaptability to the environment, and the proportion of poisonous plants could reflect the status of grasslands degradation. Little is known about age structure and self-thinning of poisonous dicotyledonous forbs in the alpine meadows on the Tibetan Plateau. We selected four poisonous dicotyledonous species, namely Anaphalis lacteal, Stellera chamaejasme, Pedicularis kansuensis, and Gentiana straminea, and determined their age structures by using number of branches, crown diameters, and plant heights and their self-thinning by using dry weights and different components (branches, leaves, and inflorescences). The populations of the four species were pyramid shaped with a rich seedling and juvenile base, which demonstrated a strong ability to increase in number rapidly and adapt to the environment. The Godron index indicated that the stability of age structures of the four species were A. lacteal > S. chamaejasme > G. straminea > P. kansuensis. Significant self-thinning was exhibited by branches of A. lacteal, branches and leaves of S. chamaejasme, and inflorescences of P. kansuensis. The self-thinning exponents from the allometric relationships between biomass and density differed at the level of branches, leaves, and inflorescences in the four poisonous forbs. We concluded that the populations of the four poisonous species were stable and able to increase in number rapidly on the Qinghai-Tibetan Plateau.

Research continually adds to our understanding of the ecological factors and biophysical processes driving frequent, large-scale fires on Great Basin rangelands in the western United States. Yet, even with advances in forecasting rangeland fire probabilities and likely ecological outcomes of fire, it remains difficult for individuals, communities, or organizations to coordinate their actions across jurisdictions and at an ecologically relevant scale to address collective wildfire risk. In this forum, we discuss current institutional arrangements that perpetuate scale mismatches in this system (i.e., institutional objectives, authorities, and capacities that limit coordinated actions to mitigate collective wildfire risk). We make a case for fireshed-scale coordination via rangeland Fireshed Councils, a proposed rangeland and fire planning and management unit that has both biophysical and social relevance to individuals and organizations engaged in fire risk mitigation. A rangeland Fireshed Council offers a venue for diverse group members to mix and match their respective rules and tools to navigate institutional barriers and capacity challenges in new ways. Operating in a collective arrangement at this scale aims to ensure that an individual's or entity's activities transcend traditional modes of planning (i.e., parcel-scale), complement concurrent management activities, and translate to fire-resilient landscapes and human communities. Rangeland Fireshed Councils will require resources and support from high governance levels for sustainability and legitimacy, as well as relative autonomy to determine how best to support local needs.

In eastern Oregon, western juniper (Juniperus occidentalis) encroachment has degraded vast amounts of wildlife habitat; thus, the removal of juniper has become a common restoration practice. Vegetative responses following juniper treatment have been well documented; however, wildlife, especially mule deer (Odocoileus hemionus) responses have not. We deployed camera traps at 40 sites within the Phillip W. Schneider Wildlife Area in northeastern Oregon to assess habitat use of wintering mule deer during two winters with different conditions, a mild winter in 2017–2018 and a harsher winter in 2018–2019. We assessed mule deer spatial habitat use using N-mixture models accounting for imperfect detection. We assessed temporal use by fitting kernel density functions to the timestamps of mule deer photographs. Spatial analysis indicated that during a mild winter, mule deer used unburned juniper treatment habitats more than untreated and unburned habitats. Once burned, however, juniper treatment habitats were used the least. During a harsher winter, mule deer spatially responded negatively to total precipitation rather than habitat conditions. Temporal analysis indicated that mule deer did not change their activity pattern between the two winters and used a mosaic of habitats to meet their daily requirements. Our results highlight the importance of juniper removal from encroached sage-steppe habitat but also emphasize the importance of habitat heterogeneity. Our results also demonstrate that wildland fires can negate the benefit of juniper treatment to wintering mule deer.

The quality of savanna habitats across the globe has declined due to increased grazing pressure from introduced ungulate species. High grazing pressure can result in a loss of perennial grass cover, which can lead to the formation of “soil scalds” on clay soils. Scalds are maintained by the formation of a soil crust, which impedes water penetration and increases runoff. Scald formation can have significant negative ecological impacts on savanna ecosystems, yet the reversibility of this process remains uncertain. In this study, we examine perennial grass decline in a north Australian savanna, where historic grazing pressure has resulted in formation of soil scalds. We tested the reversibility of scald formation by implementing a soil treatment, which involved ripping the soil to a depth of 5–10 cm and placing erosion matting on the soil surface. In addition, ungulate exclusion fencing was erected to test if the presence of feral ungulates impacted scald recovery. After a year of above-average rainfall, both control and soil treatment plots showed significant recovery in perennial and annual grass cover, as well as a significant decline in bare ground cover. However, the degree of recovery was greatest in soil treatment plots, mainly due to increases in annual grass cover. This short-term study suggests that passive recovery of scalds is possible under favorable conditions and confirms that soil mediation can accelerate revegetation. In contrast, fencing was not found to have a significant effect on vegetation recovery, which is likely due to the low ungulate density present during the study. It is important to note, however, that our results are from a single season and a long-term study is required to confirm ongoing recovery.

The concepts of ecosystem resilience and resistance (R&R) are being widely used in management planning for the big-sagebrush ecosystem of the western United States. Soil temperature and moisture regimes have been used to map geographic areas that are expected to have high, moderate, or low resilience (recovery of perennial species after disturbance) and resistance (to the spread of invasive annual grasses, most often Bromus tectorum L. or cheatgrass). While the theory underlying this framework is well developed, there have been few empirical tests of the map's utility in predicting on-the-ground management outcomes. We used data from 51 sites in Utah to relate R&R level to changes in plant cover after disturbances, using effect size analyses that standardized the magnitude of postdisturbance change (relative to predisturbance levels) across sites. Sites had been treated mechanically to reduce shrub cover or burned, and most sites were seeded. Perennial grass cover, which included native and non-native species due to the seed mixes used, increased in all R&R classes relative to predisturbance levels, but this increase was greatest at High R&R sites. Perennial forb cover increased only in the High R&R sites and decreased in Low R&R sites. Sagebrush shrub cover decreased across all R&R levels but showed evidence of recovery at High and Moderate R&R sites. These results indicate that outcomes across different disturbance types were generally in line with expectations based on the R&R map. Annual grass cover increased slightly at High and Moderate R&R sites but decreased in the Low R&R sites. These annual grass results illustrate that local site characteristics, and history may be more important factors than broad-scale soil moisture-temperature regime classifications in some cases. Nonetheless, our results overall indicate that the R&R map can be a useful tool for predicting the general outcomes of management actions in the sagebrush ecosystem.

Purple threeawn (Aristida purpurea Nutt.) is a perennial bunchgrass indigenous to much of North America that often dominates disturbed or previously overgrazed rangelands and is mostly avoided by herbivores as forage. Management of threeawn using fire and nitrogen addition can increase its forage quality and likelihood of selection by livestock. We assessed effects of fire, nitrogen fertilizer addition, and phenological stage on purple threeawn mineral concentrations the first growing season postfire on two similar sites in southeastern Montana. Fire (no fire, summer fire, fall fire) and rate of nitrogen fertilizer addition (0, 46, 80 kg N·ha^–1) were arranged in a completely randomized, fully factorial design. Samples were collected at five phenological stages throughout each growing season. Minerals were evaluated using laboratory analysis of potassium (K), calcium (Ca), phosphorus (P), sulfur (S), magnesium (Mg), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) concentrations. With no nitrogen addition, summer and fall fire increased Ca from 0.22% to 0.38% and 0.31%, respectively, S from 0.08% to 0.15% and 0.13%, and Mg from 0.06% to 0.14% and 0.12%, while fall fire decreased Fe from 289 to 176 ppm. In the vegetative stage, fire (fall and summer averaged) increased K from 0.38% to 1.08%, Ca from 0.22% to 0.35%, P from 0.10% to 0.23%, S from 0.08% to 0.16%, Mg from 0.05% to 0.13%, Zn from 19.2 ppm to 35.8 ppm and Cu from 2.8 ppm to 6.2 ppm. Increasing rate of nitrogen addition and advancing phenological stage had little to no effect on mineral concentrations relative to fire effects. Results indicate prescribed fire can increase mineral concentrations from deficient levels to exceeding requirements for growing cattle, providing more evidence supporting use of prescribed fire to increase forage quality and potential herbivore utilization of purple threeawn within 1 yr following fire.

Sagebrush ecosystems in the United States have been declining since EuroAmerican settlement, largely due to agricultural and urban development, invasive species, and altered fire regimes, resulting in loss of biodiversity and wildlife habitat. To combat continued conversion to undesirable ecological states and loss of habitat to invasive species fueled by frequent fire, a variety of fuel treatments, including networks of fuel breaks, are being implemented or proposed in sagebrush ecosystems, particularly in and around the Great Basin. In this forum paper we briefly review current knowledge of common fuel treatment approaches, their intended benefits, potential risks, and limitations. We additionally discuss challenges for fuel treatment strategies in the context of changes in climate, invasive species, wildlife habitat, and human population, and we explore how advances in geospatial technologies, monitoring, and fire behavior modeling, as well as accounting for social context, can improve the efficacy of fuels management in sagebrush ecosystems. Finally, given continued potential for ecosystem transformation, we describe approaches to future fuels management by considering the applicability of the Resist-Accept-Direct (RAD) framework. The intent of the paper is to provide scientists and land managers with key information and a forward-thinking framework for fuels science and adaptive management that can respond to both expected and unexpected changes in sagebrush rangelands.

Despite the importance of grasslands for carbon storage and climate regulation, there is uncertainty about the effect of livestock grazing intensity on aboveground carbon assimilation and belowground carbon partitioning. Furthermore, the relationship between belowground carbon allocation and arbuscular mycorrhizal fungi, which serve as a conduit for carbon movement through the plant and soil, is unclear. To investigate this, we used an in situ ¹³C stable isotope pulse-chase labeling approach in plots under seven rates of sheep grazing intensity in a steppe grassland in northern China. We quantified the allocation of carbon to plants, soil, and soil-respired CO₂ along with measurements of mycorrhizal hyphal density in the soil. With increasing grazing intensity, carbon assimilation per unit shoot biomass increased significantly, whereas carbon allocation to roots marginally decreased. Soil-respired CO₂ appeared to be independent of grazing intensity. Mycorrhizal hyphal density decreased with increasing grazing intensity and was correlated significantly with new carbon input to roots 2 d after labeling and marginally related to that of soil 1 d after the ¹³C-CO₂ pulse. Our study suggests that grazing intensity alters the distribution of carbon among different carbon pools within the plant-soil system. The results also underscored the key role of mycorrhizas as a fast route for carbon transfer from plant to soil.

Eastern redcedar (Juniperus virginiana) is rapidly encroaching on grasslands in the southern Great Plains. This has several adverse effects on the landscape including increased wildfire risk, decreased water runoff, and reduced forage available for cattle production. Several best management practices have been identified to reduce the spread of eastern redcedar, including the use of prescribed fire. However, numerous barriers exist against the use of prescribed fire such as societal acceptance or liability concerns. The purpose of this study was to determine how stakeholders from government agencies, nongovernmental organizations, and landowners perceive the use of prescribed fire to control eastern redcedar encroachment. The strengths, weaknesses, opportunities, and threats–analytical hierarchical process method was used for data analysis. The study showed that governmental and landowner stakeholders viewed that the negatives associated with prescribed fire outweigh the potential benefits. Nongovernmental organization stakeholders had differing opinions, and they were largely supportive of using prescribed fire. The results suggest that there is a need for tailored outreach to alleviate the concerns associated with risks and liabilities, as escaped prescribed fires are highly uncommon.

The study of interspecific interactions helps scientists and conservationists understand the ability of species to coexist in a given area, improving the conservation and management of ecological communities. Here we present a case study where we tested whether spatial and temporal interactions of white-tailed deer (Odocoileus virginianus), an ungulate native to Costa Rica, and horses (Equus caballus), a domestic ungulate reintroduced to a protected area, might result in avoidance. We used a paired field design with 40 camera traps deployed in two adjacent 228-ha fields within northwestern dry forest of Costa Rica during the wet season. We used general linear models to evaluate the effect of horse presence and vegetation type on white-tailed deer spatial distribution, as well as the Pianka's index to assess evidence of spatial overlapping. In addition, temporal overlap between horses and deer was assessed using the overlap coefficient, and the temporal response of white-tailed deer to horse presence was assessed using a spatially explicit null model approach. Evidence indicated that white-tailed deer used sites with horses more than sites without horses and used grass and shrubland sites more than forested sites. Within the area with horses, spatial overlap between horses and white-tailed deer was intermediate, suggesting insights of a moderate degree of spatial partitioning. Horses and white-tailed deer both showed similar activity patterns with a high degree of overlap, but our null model approach suggested neutral interaction; thus, our results indicated non-negative effects of horse presence on white-tailed deer spatiotemporal activity. Our results are limited by spatial and temporal replication, so caution is recommended when using this information to make decisions in other sites where horses and deer coexist. However, this effort provides relevant and novel information for our study area and can help decision makers to better manage ecological communities in the northwestern dry forest of Costa Rica.