Ecosystem resilience is evident 17 years after fire in Wyoming big sagebrush ecosystems

Abstract

Abstract. Recent policy has focused on prevention of wildfire in the sagebrush steppe in an effort to protect habitat for the greater sage grouse (Centrocercus urophasianus). Historically, fire return intervals in Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) ecosystems were 50-100 yr or more, but invasive species, climate change, and a legacy of intensive grazing practices have led to degraded rangeland condition, altered fire regimes and fire effects, and declines in sagebrush cover. Little is known about the long-term impacts of fire in this ecosystem in areas where grazing pressure has been removed, few invasive species exist, and fire return intervals are maintained. In this study, we quantified vegetation composition prior to prescribed burning, 1 year following fire, and 17 years after fire in a native-dominated Wyoming big sagebrush ecosystem at Hart Mountain National Antelope Refuge, Oregon, United States. Seventeen years following fire, the ecosystem was dominated by native herbaceous vegetation, with 8.3% cover of broad-leaved forbs and bunchgrasses in the understory, compared to just 3.8% cover of native herbaceous vegetation in unburned controls. Invasive annual grass cover ranged from 0.2% to 8.4% across all treatments and years (P = 0.56). One year following fire, the distance from a randomly located point and the nearest mature sagebrush was 16.6 m, but by 17 years after the fire, that distance had decreased to 2.5 m. Seventeen years after fires, shrub cover was 0.4-4% in burned plots compared to 13-24% in unburned controls. Collectively, these data demonstrate that good condition ungrazed Wyoming big sagebrush plant communities exhibited resilience following fire and maintained a native-dominated mosaic of shrubs, bunchgrasses, and forbs. Further, unburned control plots were dominated by woody vegetation and exhibited losses in herbaceous understory, possibly indicating that they are outside of their natural fire return interval. Our results illustrate that management of all habitat components, including natural disturbance and a mosaic of successional stages, is important for persistent resilience and that suppression of all fires in the sagebrush steppe may create long-term losses of heterogeneity in good condition Wyoming big sagebrush ecosystems.

Repeated fires reduce plant diversity in low‐elevation Wyoming big sagebrush ecosystems (1984–2014)

“…The results of this study may seem to conflict with other recent studies documenting Wyoming big sagebrush sagebrush recovery in the Great Basin (Ellsworth et al. , e.g., Shinneman and McIlroy ). But all of the studies we are aware of showing sagebrush recovery were conducted at cooler, wetter sites, where Wyoming big sagebrush is more resilient after fire (Chambers et al.…”

“…, Hanna and Fulgham , Ellsworth et al. ), in areas with long‐term grazing exclusion (Ellsworth et al. ), or on sites that were specifically selected because their topographic position was such that there was potential for sagebrush recovery (Shinneman and McIlroy ).…”

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

“…, Ellsworth et al. ). Forbs responded similar to perennial grasses, with increased cover at sites with medium or high burn severity and one or more fires.…”

“…Positive shifts in forb cover have been found in the sagebrush biome post‐fire (Pyle and Crawford , Ellsworth et al. ), but responses can be species‐specific (Love and Cane ).…”

Pre‐fire vegetation drives post‐fire outcomes in sagebrush ecosystems: evidence from field and remote sensing data

“…3, 4), a pattern which may be a product of competitive interactions. Certain native perennial grass species, including western wheatgrass (Pascopyrum smithii) and Sandberg bluegrass (Poa secunda), may expand after a fire due to competitive release from sagebrush, which recovers more slowly (Vale 1974, Cooper et al 2011, Davies et al 2012, Taylor et al 2014, Ellsworth et al 2016, Shinneman and McIlroy 2016, Ellsworth and Kauffman 2017, Mitchell et al 2017, Condon and Pyke 2018. Certain native perennial grass species, including western wheatgrass (Pascopyrum smithii) and Sandberg bluegrass (Poa secunda), may expand after a fire due to competitive release from sagebrush, which recovers more slowly (Vale 1974, Cooper et al 2011, Davies et al 2012, Taylor et al 2014, Ellsworth et al 2016, Shinneman and McIlroy 2016, Ellsworth and Kauffman 2017, Mitchell et al 2017, Condon and Pyke 2018.…”