Fire and development influences on sagebrush community plant groups across a climate gradient in northern Nevada

Abstract

The sagebrush biome covers much of the western United States yet is at risk from ongoing disturbances. Physical disturbances such as fire often overcome the resistance of sagebrush communities to biological disturbances such as invasion by non‐native species, but the impact of burn severity or combined disturbance types on sagebrush community composition remains unclear. We examined the relationship between native functional groups and non‐native annual grass cover to the number of fires, burn severity, anthropogenic development, and vegetation treatments in northern Nevada, USA. We used Bureau of Land Management vegetation monitoring plots and existing climate, fire, and vegetation treatment databases to explore relationships using beta regression. After accounting for mean annual precipitation and temperature, and elevation, we quantified functional group mean cover related to levels of burn severity, numbers of fires, development, and vegetation treatments. Native herbaceous (grass and forb) groups were resilient to fire, but fire caused large declines in shrub and sagebrush cover. Non‐native annual grass cover was associated with higher burn severity and the first fire at a site. We did not find evidence that post‐fire restoration treatments were associated with increased native cover or decreased non‐native cover. However, shrub control and soil disturbing treatments (discing and chaining) were associated with decreased native perennial grass cover and increased non‐native annual grass cover. Functional groups displayed varying patterns related to anthropogenic development and fire. For example, development had a larger impact on non‐native cover at lower levels of burn severity, whereas forbs increased following fire only at lower levels of development. Although in some cases sagebrush communities showed resilience to disturbance, our results showed resistance to invasion by non‐native annual grasses can be overcome by combinations of disturbances at lower levels or by severe events.

Vegetation change over 140 years in a sagebrush landscape of the Rio Grande del Norte National Monument, New Mexico, USA

“…These results provide a new, local, southwestern United States perspective on the broad concern regarding declining sagebrush, which has largely come from research in the Great Basin (e.g., Wood et al, 2019). Increases in other shrub species have been documented in arid and semi‐arid grasslands around the globe, as well as in other parts of New Mexico during the last century (Huenneke et al, 2002; D'Odorico et al, 2012; Brunelle et al, 2014; Bestelmeyer et al, 2018).…”

Post-Fire Vegetation Response in a Repeatedly Burned Low-Elevation Sagebrush Steppe Protected Area Provides Insights About Resilience and Invasion Resistance

“…A second reason for low variation in grass cover among ecological sites over time in our study area was the shared attributes of soil temperature and moisture regime across all sites and only subtle differences in soil texture, historical and degraded plant community composition, and other site attributes described by NRCS for the ecological sites in the study area. Similarly, a third reason for low variation among ecological sites was the homogenizing effect (sensu Foster et al, 2013) of the 2011 fire, with likely cumulative influences from past fires and grazing (Chambers and Wisdom, 2009;Davies et al, 2012;Bernards and Morris, 2016;Mahood and Balch, 2019;Wood et al, 2019;Ellsworth et al, 2020). This homogenization has occurred throughout the study area across ecological sites, as community composition of all ecological sites converged toward an annual grass state.…”

Antecedent climatic conditions spanning several years influence multiple land-surface phenology events in semi-arid environments

“…Surprisingly, fire never appeared in our sets of top predictors. However, fire can radically change vegetation phenology, wherein its effects last for multiple years, depending on the fire severity and speed of recovery (Miller et al, 2013;Vermeire and Russell, 2018;Wood et al, 2019;Vanderhoof et al, 2020;Gemitzi and Koutsias, 2021;Wang et al, 2021). If fire resulted in a change in land-cover type, pixels would have shifted vegetation class (such as from forest to grassland) in our approach.…”