Jeremy D. Maestas

BIODIVERSITY AND LAND-USE CHANGE IN THE AMERICAN MOUNTAIN WEST

Rural private lands in the Mountain West of the United States are undergoing a profound land‐use conversion, from agriculture to low‐density residential or exurban development, though little scientific study documents the ecological consequences of this change. Nongovernmental conservation organizations are working with ranchers to keep rangeland out of development and in ranching, ostensibly because these organizations believe that biodiversity is better protected on ranches than on exurban developments. We compared plant and wildlife communities across the principal rural land uses in the Mountain West: protection, livestock ranching, and exurban development. Native plant and faunal biodiversity was better maintained on ranches and protected areas than on exurban developments. Exurban developments favored species that were nonnative or adapted to human‐altered environments. The continued conversion of ranches to exurban development suggests a long‐term alteration of the regions natural heritage.

Using resistance and resilience concepts to reduce impacts of invasive annual grasses and altered fire regimes on the sagebrush ecosystem and greater sage-grouse: A strategic multi-scale approach

This Report provides a strategic approach for conservation of sagebrush ecosystems and Greater Sage- Grouse (sage-grouse) that focuses specifically on habitat threats caused by invasive annual grasses and altered fire regimes. It uses information on factors that influence (1) sagebrush ecosystem resilience to disturbance and resistance to invasive annual grasses and (2) distribution, relative abundance, and persistence of sage-grouse populations to develop management strategies at both landscape and site scales. A sage-grouse habitat matrix links relative resilience and resistance of sagebrush ecosystems with sage-grouse habitat requirements for landscape cover of sagebrush to help decision makers assess risks and determine appropriate management strategies at landscape scales. Focal areas for management are assessed by overlaying matrix components with sage-grouse Priority Areas for Conservation (PACs), breeding bird densities, and specific habitat threats. Decision tools are discussed for determining the suitability of focal areas for treatment and the most appropriate management treatments.

Short-Term Response of Sage-Grouse Nesting to Conifer Removal in the Northern Great Basin ☆

ABSTRACT Coniferwoodlands expanding into sage-steppe (Artemisia spp.) are a threat to sagebrush obligate species including the imperiled greater sage-grouse (Centrocercus urophasianus). Conifer removal is accelerating rapidly despite a lack of empirical evidence to assess outcomes to grouse. Using a before-after-control-impact design, we evaluated short-term effects of conifer removal on nesting habitat use by monitoring 262 sage-grouse nests in the northern Great Basin during 2010–2014. Tree removal made available for nesting an additional 28% of the treatment landscape by expanding habitat an estimated 9603 ha (3201 ha [±480 SE] annually). Relative probability of nesting in newly restored sites increased by 22% annually, and femaleswere 43%more likely to nestwithin 1000 m of treatments. From 2011 (pretreatment) to 2014 (3 yr after treatments began), 29% of the marked population (9.5% [±1.2 SE] annually) had shifted its nesting activities into mountain big sagebrush habitats that were cleared of encroaching conifer. Grouping treatments likely contributed to beneficial outcomes for grouse as individual removal projects averaged just 87 ha in size but cumulatively covered a fifth of the study area. Collaboratively identifying future priority watersheds and implementing treatments across public and private ownerships is vital to effectively restore the sage-steppe ecosystem for nesting sage-grouse.

Mapping Tree Canopy Cover in Support of Proactive Prairie Grouse Conservation in Western North America

ABSTRACT Invasivewoody plant expansion is a primary threat driving fragmentation and loss of sagebrush (Artemisia spp.) and prairie habitats across the central andwestern United States. Expansion of native woody plants, including conifer (primarily Juniperus spp.) and mesquite (Prosopis spp.), over the past century is primarily attributable to wildfire suppression, historic periods of intensive livestock grazing, and changes in climate. To guide successful conservation programs aimed at reducing top-down stressors, we mapped invasive woody plants at regional scales to evaluate landscape level impacts, target restoration actions, and monitor restoration outcomes. Our overarching goal was to produce seamless regional products across sociopolitical boundaries with resolution fine enough to depict the spatial extent and degree of woody plant invasion relevant to greater sage-grouse (Centrocercus urophasianus) and lesser prairie-chicken (Tympanuchus pallidicinctus) conservation efforts. We mapped tree canopy cover at 1-m spatial resolution across an 11-state region (508 265 km2). Greater than 90% of occupied lesser prairie-chicken habitat was largely treeless for conifers (<1% canopy cover), whereas > 67% was treeless for mesquite. Conifers in the higher canopy cover classes (16–50% and >50% canopy cover) were scarce (<2% and 1% canopy cover), as was mesquite (<5% and 1% canopy cover). Occupied habitat by sagegrouse was more variable but also had a relatively large proportion of treeless areas ( =71, SE=5%). Lowto moderate levels of conifer cover (1–20%) were fewer ( = 23, SE = 5%) as were areas in the highest cover class (>50%; = 6, SE = 2%). Mapping indicated that a high proportion of invading woody plants are at a low to intermediate level. Canopy cover maps for conifer and mesquite resulting from this study provide the first and most geographically complete, high-resolution assessment of woody plant cover as a top-down threat to western sage-steppe and prairie ecosystems.

Using resilience and resistance concepts to manage persistent threats to sagebrush ecosystems and greater sage-grouse

ABSTRACT Conservation of imperiled species often demands addressing a complex suite of threats that undermine species viability. Regulatory approaches, such as the US Endangered Species Act (1973), tend to focus on anthropogenic threats through adoption of policies and regulatory mechanisms. However, persistent ecosystem-based threats, such as invasive species and altered disturbance regimes, remain critical issues for most at-risk species considered to be conservation-reliant. We describe an approach for addressing persistent ecosystem threats to at-risk species based on ecological resilience and resistance concepts that is currently being used to conserve greater sage-grouse (Centrocercus urophasianus) and sagebrush ecosystems. The approach links biophysical indicators of ecosystem resilience and resistance with species-specific population and habitat requisites in a risk-based framework to identify priority areas for management and guide allocation of resources to manage persistent ecosystem-based threats. US federal land management and natural resource agencies have adopted this framework as a foundation for prioritizing sage-grouse conservation resources and determining effective restoration and management strategies. Because threats and strategies to address them cross-cut program areas, an integrated approach that includes wildland fire operations, postfire rehabilitation, fuels management, and habitat restoration is being used. We believe this approach is applicable to species conservation in other largely intact ecosystems with persistent, ecosystem-based threats.

Tapping Soil Survey Information for Rapid Assessment of Sagebrush Ecosystem Resilience and Resistance

On the Ground Emerging applications of ecosystem resilience and resistance concepts in sagebrush ecosystems allow managers to better predict and mitigate impacts of wildfire and invasive annual grasses. Widely available soil survey information can be harnessed to spatially depict and evaluate relative resilience and resistance from regional to site scales. New products and tools illustrate how managers can use soils data to inform rapid risk assessments, determine appropriate management strategies, and prioritize resources to maintain and restore functioning sagebrush ecosystems.

Bird Responses to Removal of Western Juniper in Sagebrush-Steppe☆

ABSTRACT We investigated bird abundance in response to western juniper (Juniperus occidentalis) removal using a short-term chronosequence approach and generated estimates of density and responses to management for the most abundant species. Stands targeted for tree removal were primarily in the middle stages of juniper encroachment (Phase II, 7 851 ha). Trees were removed using hand felling combined with either lop and scatter, single tree burning, or jackpot burning, which were carried out to minimize loss of shrub cover. Brewers sparrow (Spizella breweri) density was greater at treated versus untreated portions of the study area. At sites in the third year following tree removal, Brewers sparrow density was 23.6 (95% confidence interval [CI]: 19.4–27.8) territories per km2 higher than locations that had not yet been treated. This equates to a net increase of 1 212-1 737 nesting pairs within the project area. Green-tailed towhee increased by 4.6 (95% CI: 3.1–6.1) territories per km2 for an estimated project wide increase of 194–381 nesting pairs, and vesper sparrow (Poocetes gramineus) increased by 6.5 (95% CI: 4.6–8.4) territories per km2 corresponding to an estimated increase of 460–559 nesting pairs within the project area. Density of gray flycatcher (Empidonax wrighti) was lower in cut areas, and over the entire project area we estimate a net loss of 183–486 nesting pairs as a result of juniper tree removal. This study demonstrates that conifer removal projects designed to retain shrub cover and structure can have benefits to multiple species of ground and shrub nesting birds, including several species of conservation concern.

Phenology largely explains taller grass at successful nests in greater sage-grouse

Abstract Much interest lies in the identification of manageable habitat variables that affect key vital rates for species of concern. For ground‐nesting birds, vegetation surrounding the nest may play an important role in mediating nest success by providing concealment from predators. Height of grasses surrounding the nest is thought to be a driver of nest survival in greater sage‐grouse (Centrocercus urophasianus; sage‐grouse), a species that has experienced widespread population declines throughout their range. However, a growing body of the literature has found that widely used field methods can produce misleading inference on the relationship between grass height and nest success. Specifically, it has been demonstrated that measuring concealment following nest fate (failure or hatch) introduces a temporal bias whereby successful nests are measured later in the season, on average, than failed nests. This sampling bias can produce inference suggesting a positive effect of grass height on nest survival, though the relationship arises due to the confounding effect of plant phenology, not an effect on predation risk. To test the generality of this finding for sage‐grouse, we reanalyzed existing datasets comprising >800 sage‐grouse nests from three independent studies across the range where there was a positive relationship found between grass height and nest survival, including two using methods now known to be biased. Correcting for phenology produced equivocal relationships between grass height and sage‐grouse nest survival. Viewed in total, evidence for a ubiquitous biological effect of grass height on sage‐grouse nest success across time and space is lacking. In light of these findings, a reevaluation of land management guidelines emphasizing specific grass height targets to promote nest success may be merited.

Better living through conifer removal: A demographic analysis of sage-grouse vital rates

Sagebrush (Artemisia spp.) obligate wildlife species such as the imperiled greater sage-grouse (Centrocercus urophasianus) face numerous threats including altered ecosystem processes that have led to conifer expansion into shrub-steppe. Conifer removal is accelerating despite a lack of empirical evidence on grouse population response. Using a before-after-control-impact design at the landscape scale, we evaluated effects of conifer removal on two important demographic parameters, annual survival of females and nest survival, by monitoring 219 female sage-grouse and 225 nests in the northern Great Basin from 2010 to 2014. Estimates from the best treatment models showed positive trends in the treatment area relative to the control area resulting in an increase of 6.6% annual female survival and 18.8% nest survival relative to the control area by 2014. Using stochastic simulations of our estimates and published demographics, we estimated a 25% increase in the population growth rate in the treatment area relative to the control area. This is the first study to link sage-grouse demographics with conifer removal and supports recommendations to actively manage conifer expansion for sage-grouse conservation. Sage-grouse have become a primary catalyst for conservation funding to address conifer expansion in the West, and these findings have important implications for other ecosystem services being generated on the wings of species conservation.

SRM Wildlife Habitat Committee

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