Identifying key climate and environmental factors affecting rates of post-fire big sagebrush (Artemisia tridentata) recovery in the northern Columbia Basin, USA

Abstract

Sagebrush steppe of North America is considered highly imperilled, in part owing to increased fire frequency. Sagebrush ecosystems support numerous species, and it is important to understand those factors that affect rates of post-fire sagebrush recovery. We explored recovery of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and basin big sagebrush (A. tridentata ssp. tridentata) communities following fire in the northern Columbia Basin (Washington, USA). We sampled plots across 16 fires that burned in big sagebrush communities from 5 to 28 years ago, and also sampled nearby unburned locations. Mixed-effects models demonstrated that density of large–mature big sagebrush plants and percentage cover of big sagebrush were higher with time since fire and in plots with more precipitation during the winter immediately following fire, but were lower when precipitation the next winter was higher than average, especially on soils with higher available water supply, and with greater post-fire mortality of mature big sagebrush plants. Bunchgrass cover 5 to 28 years after fire was predicted to be lower with higher cover of both shrubs and non-native herbaceous species, and only slightly higher with time. Post-fire recovery of big sagebrush in the northern Columbia Basin is a slow process that may require several decades on average, but faster recovery rates may occur under specific site and climate conditions.

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

“…According to analyses of field data, cover of most exotic functional groups in burned areas increased whereas native shrub and sagebrush cover decreased between 1982 and 2016 (Table 1), a finding consistent with numerous reports of sagebrush ecosystems in the northern Great Basin being converted to degraded grasslands dominated by exotic plants (Whisenant 1990, Davies et al 2012, Shinneman and McIlroy 2016. Component data had a similar pattern whereby shrub and sagebrush cover declined in burned plots; however, cover of herbaceous components did not change (Table 1).…”

“…7). The relatively rapid rebound of certain herbaceous functional groups is consistent with work showing that annual and perennial herbaceous species may recover within a few years after burning (Miller et al 2013, Hanna and Fulgham 2015, Shinneman and McIlroy 2016. S2).…”

“…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.…”

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

“…, Reed‐Dustin et al. , Shinneman and McIlroy ). There has been disagreement in the past about the historical fire return interval for Wyoming big sagebrush.…”

Greater sage-grouse science (2015–17)—Synthesis and potential management implications

“…Mountain big sagebrush (A. t. vaseyana) communities tend to exhibit higher resilience to wildfire and often exhibit an increase in forb cover after burning relative to Wyoming big sagebrush (A. t. wyomingensis) communities (Wrobleski and Kauffman, 2003). Because of loss of sagebrush cover after wildfire and long recovery times for sagebrush (for example, Shinneman and McIlroy, 2016), recent wildfires have been associated with negative sage-grouse population trends (see review in Connelly and others, 2000a) and increased lek abandonment (Hess and Beck, 2012). Wildfire (Nelle and others, 2000) and prescribed fire (Rhodes and others, 2010) have negatively affected sage-grouse habitats.…”