The potential importance of unburned islands as refugia for the persistence of wildlife species in fire‐prone ecosystems

Abstract

The persistence of wildlife species in fire‐prone ecosystems is under increasing pressure from global change, including alterations in fire regimes caused by climate change. However, unburned islands might act to mitigate negative effects of fire on wildlife populations by providing habitat in which species can survive and recolonize burned areas. Nevertheless, the characteristics of unburned islands and their role as potential refugia for the postfire population dynamics of wildlife species remain poorly understood. We used a newly developed unburned island database of the northwestern United States from 1984 to 2014 to assess the postfire response of the greater sage‐grouse ( Centrocercus urophasianus ), a large gallinaceous bird inhabiting the sagebrush ecosystems of North America, in which wildfires are common. Specifically, we tested whether prefire and postfire male attendance trends at mating locations (leks) differed between burned and unburned areas, and to what extent postfire habitat composition at multiple scales could explain such trends. Using time‐series of male counts at leks together with spatially explicit fire history information, we modeled whether male attendance was negatively affected by fire events. Results revealed that burned leks often exhibit sustained decline in male attendance, whereas leks within unburned islands or >1.5 km away from fire perimeters tend to show stable or increasing trends. Analyses of postfire habitat composition further revealed that sagebrush vegetation height within 0.8 km around leks, as well elevation within 0.8 km, 6.4 km, and 18 km around leks, had a positive effect on male attendance trends. Moreover, the proportion of the landscape with cheatgrass ( Bromus tectorum ) cover >8% had negative effects on male attendance trends within 0.8 km, 6.4 km, and 18 km of leks, respectively. Synthesis and applications . Our results indicate that maintaining areas of unburned vegetation within and outside fire perimeters may be crucial for sustaining sage‐grouse populations following wildfire. The role of unburned islands as fire refugia requires more attention in wildlife management and conservation planning because their creation, protection, and maintenance may positively affect wildlife population dynamics in fire‐prone ecosystems.

Expanding the invasion footprint:Ventenata dubiaand relationships to wildfire, environment, and plant communities in the Blue Mountains of the Inland Northwest, USA

“…Although Artemisia tridentata seeds have been found to survive in the seedbank for up to five years post fire, few seeds germinate after the first year (Meyer, 2008). Re‐establishment after fire is thought to occur very slowly for Artemisia rigida and is likely maintained by short‐distance dispersal from nearby unburned sagebrush islands acting as fire refugia (Agee, 1994; Steenvoorden, Meddens, Martinez, Foster, & Kissling, 2019). The loss of Artemisia rigida and Artemisia arbuscula could have broad ecosystem effects.…”

Post-fire movements of Pacific marten (Martes caurina) depend on the severity of landscape change

“…However, large wildfires leave a heterogeneous footprint in forests as some areas burn more intensely than others [ 25 ]. Some residual habitats in the form of surviving trees, snags, and deadfall persist for decades post-fire, offering prospects for wildlife persistence and recolonization [ 26 – 28 ].…”

Acute and lagged fitness consequences for a sagebrush obligate in a post mega‐wildfire landscape

“…We suspect that carrying capacity decreased after the fire due to the vast amount of sagebrush loss and philopatric behavior of the species thus, patterns in λ during the first 3 years post‐fire were consistent with what we would predict under an extreme disturbance. The continued decline in λ since 2016 suggested the loss of 186,972 ha of sagebrush habitat and slow regeneration of sagebrush plants post‐fire may prolong recovery of sage‐grouse after a mega‐wildfire (Steenvoorden et al, 2019). Mean estimates of λ during 2016–2018 were much lower in the Trout Creek study area (0.75) compared to a study in Oregon during the same time period that was not affected by fire (0.93; Olsen et al, 2021).…”

“…The response of sage-grouse to the loss of sagebrush is overwhelmingly negative across their range as disturbances that remove or render sagebrush unusable have demographic consequences (Aldridge & Boyce, 2007;Dzialak et al, 2011;Foster et al, 2019;Kirol et al, 2015;LeBeau et al, 2014). Wildfire that kills sagebrush has negative consequences on lek attendance (Coates et al, 2015(Coates et al, , 2016Dudley et al, 2021;Hess & Beck, 2012;Steenvoorden et al, 2019) and key vital rates like nest survival (NS) (Anthony et al, 2021;Foster et al, 2019;Lockyer et al, 2015) and adult female survival (Foster et al, 2019). Even smaller sized prescribed fires (<6000 ha) that remove sagebrush have been associated with declines in sage-grouse populations (Connelly et al, 2000;Fischer, 1994).…”