Refining the cheatgrass-fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends

David S. Pilliod; Justin L. Welty; Robert S. Arkle

doi:10.1002/ece3.3414

Refining the cheatgrass-fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends

Ecology and Evolution ◽

10.1002/ece3.3414 ◽

2017 ◽

Vol 7 (19) ◽

pp. 8126-8151 ◽

Cited By ~ 32

Author(s):

David S. Pilliod ◽

Justin L. Welty ◽

Robert S. Arkle

Keyword(s):

Great Basin ◽

Fuel Composition ◽

Fire Cycle ◽

Precipitation Timing

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Wildfire, climate, and invasive grass interactions negatively impact an indicator species by reshaping sagebrush ecosystems

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1606898113 ◽

2016 ◽

Vol 113 (45) ◽

pp. 12745-12750 ◽

Cited By ~ 47

Author(s):

Peter S. Coates ◽

Mark A. Ricca ◽

Brian G. Prochazka ◽

Matthew L. Brooks ◽

Kevin E. Doherty ◽

...

Keyword(s):

Great Basin ◽

Indicator Species ◽

Spatial Scales ◽

Fire Regimes ◽

Invasive Grass ◽

Sage Grouse ◽

Climatic Effects ◽

Ecosystem Recovery ◽

Fire Cycle ◽

Wildlife Populations

Iconic sagebrush ecosystems of the American West are threatened by larger and more frequent wildfires that can kill sagebrush and facilitate invasion by annual grasses, creating a cycle that alters sagebrush ecosystem recovery post disturbance. Thwarting this accelerated grass–fire cycle is at the forefront of current national conservation efforts, yet its impacts on wildlife populations inhabiting these ecosystems have not been quantified rigorously. Within a Bayesian framework, we modeled 30 y of wildfire and climatic effects on population rates of change of a sagebrush-obligate species, the greater sage-grouse, across the Great Basin of western North America. Importantly, our modeling also accounted for variation in sagebrush recovery time post fire as determined by underlying soil properties that influence ecosystem resilience to disturbance and resistance to invasion. Our results demonstrate that the cumulative loss of sagebrush to direct and indirect effects of wildfire has contributed strongly to declining sage-grouse populations over the past 30 y at large spatial scales. Moreover, long-lasting effects from wildfire nullified pulses of sage-grouse population growth that typically follow years of higher precipitation. If wildfire trends continue unabated, model projections indicate sage-grouse populations will be reduced to 43% of their current numbers over the next three decades. Our results provide a timely example of how altered fire regimes are disrupting recovery of sagebrush ecosystems and leading to substantial declines of a widespread indicator species. Accordingly, we present scenario-based stochastic projections to inform conservation actions that may help offset the adverse effects of wildfire on sage-grouse and other wildlife populations.

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Fire history of a central Nevada pinyon–juniper woodland

Canadian Journal of Forest Research ◽

10.1139/x09-078 ◽

2009 ◽

Vol 39 (8) ◽

pp. 1589-1599 ◽

Cited By ~ 21

Author(s):

John M. Bauer ◽

Peter J. Weisberg

Keyword(s):

Great Basin ◽

Fire History ◽

Fire Regime ◽

Climatic Conditions ◽

Spatial And Temporal Variation ◽

Fire Scars ◽

Survivorship Analysis ◽

Fire Cycle ◽

Superposed Epoch Analysis ◽

Fire Exclusion

Our study reconstructed fire history (1445–2006) from tree rings for a Great Basin single-needle pinyon pine ( Pinus monophylla Torr & Frém.) – Utah juniper ( Juniperus osteosperma (Torr.) Little) woodland. Information from multiple lines of evidence, including dateable fire scars (n = 83), tree demography, and charred coarse woody debris, was used to quantify fire frequency, severity, and extent. Fire cycle models were developed using survivorship analysis of time-since-fire estimates. We investigated the spatial and temporal variation in historical fire regime, addressing the plausibility of postsettlement fire exclusion as an explanation for increased woodland area and density since the late 1800s. Historical fire regime was characterized by infrequent, small, high-severity fires. Estimated fire cycle (1570–1880) was 427 years, with no evidence of postsettlement stand-replacing fires. Topographic analyses indicated that in this drought-prone landscape, more mesic conditions favor continuous fuels that lead to more frequent or extensive fire. Superposed epoch analysis showed increased fire occurrence during drought years but with no influence of antecedent climatic conditions. More frequent grassland and shrubland fires were recorded by fire scars near valley floors. Thus, anthropogenic fire exclusion in adjacent, shrub-dominated communities presents a plausible mechanism for woodland expansion in the study area. However, there is little ecological justification for reintroducing fire to areas of historic woodland, where effects of fire exclusion have been minimal.

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