Data from: Historical fire regimes and contemporary fire effects within sagebrush habitats of Gunnison Sage-grouse

The historical role of fire in sagebrush (Artemisia tridentata) landscapes
remains poorly understood yet is important to inform management and
conservation of obligate species such as the threatened Gunnison
Sage-grouse (GUSG; Centrocercus minimus). We reconstructed fire histories
from tree-ring fire-scars at sagebrush-forest ecotones (10 sites, 111
trees) to better understand the role of fire in sagebrush landscapes of
the Upper Gunnison Basin (UGB), Colorado, and how fire may have changed
following European-American settlement. We assessed likely influences of
historical fire by surveying plant composition and structure at 100
sagebrush sites with and without recent (2001–2020) fire. 
Tree-ring fire-scars revealed a history of repeated low-severity fire at
sagebrush-forest ecotones until 1892, followed by over a century without
fire. Between 1684 and 1892, the mean fire interval (MFI) among sites
averaged 41.3 years (ranging from 18.2 to 79.7 years). Fire over this
period occurred synchronously at two or more sites on average every 23.6
years, consistent with spread between sites. Most (70%) of the historical
fires burned in the early growing season when strong winds can spread fire
through sagebrush. Recent burns, relative to unburned sites exhibited
greater reductions in sagebrush (Artemisia tridentata; 27% vs. 6%) and
concomitant increases in herbaceous (40% vs. 55%) cover. These differences
declined with time since fire but persisted for at least two decades.
Burns were dominated by a suite of native perennial grasses, forbs, and a
re-sprouting shrub species. Historically, such openings may have served as
seasonal GUSG habitat. Burns exhibited slightly increased cover (4% vs.
1%) of a widely-planted non-native perennial grass, crested wheatgrass
(Agropyron cristatum).  Our results suggest that parts of the UGB
sagebrush landscapes were characterized historically by frequent fire and
dynamic vegetation mosaics that included open, grassy patches. These
findings are consistent with the use of prescribed fire to restore and
maintain this ecological process and vegetation heterogeneity. However,
the contemporary context for fire has changed, and now includes
substantially reduced (Endangered Species Act) ESA-listed GUSG
populations, increased risk of non-native plant invasion, and climate
warming. These circumstances highlight new risks, information needs, and
opportunities for key knowledge co-production via management-research
partnerships.