Research and Publications
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We investigated habitat selection by 28 male greater sage-grouse during each of 3 years after a 113,000-ha wildfire in a sagebrush steppe ecosystem in Idaho and Oregon. During the study period, seeding and herbicide treatments were applied for habitat restoration. We evaluated sage-grouse responses to vegetation and post-fire restoration treatments. Throughout the 3 years post-fire, sage-grouse avoided areas with high exotic annual grass cover but selected strongly for recovering sagebrush and moderately strongly for perennial grasses. By the third year post-fire, they preferred high-density sagebrush, especially in winter when sagebrush is the primary component of the sage-grouse diet. Sage-grouse preferred forb habitat immediately post-fire, especially in summer, but this selection preference was less strong in later years. They also selected areas that were intensively treated with herbicide and seeded with sagebrush, grasses, and forbs, although these responses varied with time since treatment.
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We investigated the long-term (+80 yrs.) effects of moderate grazing by cattle on sagebrush-induced spatial heterogeneity in soil nutrients, herbaceous vegetation, and ground cover in sagebrush-bunchgrass steppe communities at eight sites in southeastern Oregon. Each site consisted of a long-term grazing exclosure and an adjacent grazed area. Almost all measured herbaceous vegetation (cover, density, diversity, and evenness) and ground cover variables differed between canopy and interspace microsites. Grazing did not influence the effects of microsites on most measured herbaceous vegetation characteristics and ground cover variables. Available soil nutrients were not influenced by grazing, but the majority differed between microsites. The limited effect of moderate grazing on shrub-induced spatial heterogeneity provides evidence that sagebrush exerts a strong influence on patterns of soil nutrients and herbaceous vegetation in sagebrush-bunchgrass communities.
We compared moderate grazing during the off season with not grazing in five Wyoming big sagebrush−bunchgrass communities in the northern Great Basin. Treatments were applied annually for 10 yr (2009−2010 through 2018−2019). Plant community characteristics were measured after treatments had been applied from 6 to 10 yr. Off-season grazing reduced exotic annual grass density and cover. After a decade, annual grass cover was twofold greater in ungrazed areas. Sandberg bluegrass density increased with off-season grazing, but large bunchgrass density was similar between off-season grazed and ungrazed areas. Perennial and annual forb density and cover were similar between off-season grazed and ungrazed treatments. Biological soil crust cover was also similar between off-season grazed and ungrazed areas.
We compared 1) burned and ungrazed (burned), 2) off-season, moderately grazed and unburned (grazed), and 3) ungrazed and unburned (control) treatments at five Wyoming big sagebrush sites in southeastern Oregon for half a decade. Fire, but not off-season grazing, substantially increased exotic annual grass cover and abundance. Vegetation cover and density were generally similar between grazed and control areas. In contrast, at the end of the study exotic annual grass cover and density were over fourfold greater in burned areas. Exotic annual grass became the dominant plant group in burned areas, but not in grazed and control areas. Cover and density of annual forbs, predominately non-native species, were generally greater in the burned compared with grazed and control treatments. Fire also decreased soil biological crust cover and sagebrush cover and density compared with grazed and control treatments. This study provides strong evidence that fire is a threat to the sustainability of Wyoming big sagebrush communities at risk of exotic annual grass dominance, but that off-season, moderate grazing poses little risk. However, considering the spatial extent of our study was limited, further evaluations are needed across a larger geographic area.
Several important paths to improved success of native plant restoration are clear: recognize and leverage intraspecific variation and local adaptation in plants, increase the development and use of seed transfer guidance, build seed production partnerships to benefit restoration and local communities, and be ready and willing to adopt changes to the way things are done when the evidence is clear that change will help.
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Study results suggest increasing the frequency of disturbances (a lower disturbance return interval [DRI]) would reduce the percentage of high-severity fire on landscape but not the total amount of wildfire in general. However, a higher DRI reduced carbon storage and sequestration, particularly in management strategies that emphasized prescribed fire over hand or mechanical fuel treatments.
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Here, we use lands administered by the US Forest Service as a study system to assess the causes, ignition locations, structure loss, and social and biophysical factors associated with cross-boundary fire activity over the past three decades. Results show that cross-boundary fires were primarily caused by humans on private lands. Cross-boundary ignitions, area burned, and structure losses were concentrated in California. Public lands managed by the US Forest Service were not the primary source of fires that destroyed the most structures. Cross-boundary fire activity peaked in moderately populated landscapes with dense road and jurisdictional boundary networks. Fire transmission is increasing, and evidence suggests it will continue to do so in the future. Effective cross-boundary fire risk management will require cross-scale risk co-governance. Focusing on minimizing damages to high-value assets may be more effective than excluding fire from multijurisdictional landscapes.
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Post-wildfire extreme rainfall events can have destructive impacts in the western United States. Using two climate model large ensembles, we assess the future risk of extreme fire weather events being followed by extreme rainfall in this region. By mid-21st century, in a high warming scenario (RCP8.5), we report large increases in the number of extreme fire weather events followed within 1 year by at least one extreme rainfall event. By 2100, the frequency of these compound events increases by 100% in California and 700% in the Pacific Northwest in the Community Earth System Model v1 Large Ensemble. We further project that more than 90% of extreme fire weather events in California, Colorado, and the Pacific Northwest will be followed by at least three spatially co-located extreme rainfall events within five years. Our results point to a future with substantially increased post-fire hydrologic risks across much of the western United States.
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The monitoring for adaptive management of the 2015 Soda Megafire area (113,000 Ha) sampled up to 2000 observation plots in each of five post-fire years, and provided important insights on challenges, solutions, and insights that can be applied to monitoring future burned areas.
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This study involved a review of available spatial products to assess advances in, and barriers to, applying contemporary model-based maps to support rangeland management. We found dozens of regional data products describing cheatgrass or annual herbaceous cover and few maps describing ventenata or medusahead. Over the past decade, IAG spatial data increased in spatial and temporal resolution and increasingly used response variables that indicate the severity of infestation such as percent cover. Despite improvements, use of such data is limited by the time required to find, compare, understand, and translate model-based maps into management strategy. There is also a need for products with higher spatial resolution and accuracy. In collaboration with a multipartner stakeholder group, we identified key considerations that guide selection of IAG spatial data products for use by land managers and other users. On the basis of these considerations, we discuss issues that contribute to a research-implementation gap between users and product developers and suggest future directions for improved development of management-ready spatial products.