Chad S. Boyd

Ecology and management of sage-grouse and sage-grouse habitat

Abstract Sage-grouse (Centrocercus urophasianus and C. minimus) historically inhabited much of the sagebrush-dominated habitat of North America. Today, sage-grouse populations are declining throughout most of their range. Population dynamics of sage-grouse are marked by strong cyclic behavior. Adult survival is high, but is offset by low juvenile survival, resulting in low productivity. Habitat for sage-grouse varies strongly by life-history stage. Critical habitat components include adequate canopy cover of tall grasses (≥ 18 cm) and medium height shrubs (40–80 cm) for nesting, abundant forbs and insects for brood rearing, and availability of herbaceous riparian species for late-growing season foraging. Fire ecology of sage-grouse habitat changed dramatically with European settlement. In high elevation sagebrush habitat, fire return intervals have increased (from 12–24 to > 50 years) resulting in invasion of conifers and a consequent loss of understory herbaceous and shrub canopy cover. In lower elevation sagebrush habitat, fire return intervals have decreased dramatically (from 50–100 to < 10 years) due to invasion by annual grasses, causing loss of perennial bunchgrasses and shrubs. Livestock grazing can have negative or positive impacts on sage-grouse habitat depending on the timing and intensity of grazing, and which habitat element is being considered. Early season light to moderate grazing can promote forb abundance/availability in both upland and riparian habitats. Heavier levels of utilization decrease herbaceous cover, and may promote invasion by undesirable species. At rates intended to produce high sagebrush kill, herbicide-based control of big sagebrush may result in decreased habitat quality for sage-grouse. Light applications of tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea) can decrease canopy cover of sagebrush and increase grass and forb production which may be locally important to nesting and foraging activities. The ability of resource managers to address sage-grouse habitat concerns at large scales is aided greatly by geomatics technology and advances in landscape ecology. These tools allow unprecedented linkage of habitat and population dynamics data over space and time and can be used to retroactively assess such relationships using archived imagery. The present sage-grouse decline is a complex issue that is likely associated with multiple causative factors. Solving management issues associated with the decline will require unprecedented cooperation among wildlife biology, range science, and other professional disciplines.

Managing Complex Problems in Rangeland Ecosystems

Abstract Management of rangelands, and natural resources in general, has become increasingly complex. There is an atmosphere of increasing expectations for conservation efforts associated with a variety of issues from water quality to endangered species. We argue that many current issues are complex by their nature, which influences how we approach them. We define a complex problem as one that varies in time and space. In other words, one answer may not be correct for all sites or during all years. For simple problems a generalized answer may be sufficient, and even for complex problems, general rules provide a good starting point. However, we suggest that it is important to distinguish between simple and complex problems. Several key obstacles emerge when considering complex natural resource problems, namely, 1) no single entity can handle all aspects of the problem and 2) significant knowledge gaps exist and will continue to exist into the future. We suggest that overcoming these obstacles will benefit from 1) a framework for effective partnerships and 2) a mechanism for continuous learning. Managing complex problems will require some combination of the following: 1) a process-based understanding of the problem (i.e., what causes variation in time and space), 2) adaptive management, and 3) effective coordination of research and management. There are many examples of organizations applying portions of these approaches to complex problems; however, it seems that in many cases the process has simply evolved in that direction rather than being a planned strategy. We suggest that as a profession we need to have a discussion about the nature of the problems we are addressing and how researchers and managers can jointly address these problems.

Restoring the Sagebrush Component in Crested Wheatgrass–Dominated Communities

Abstract Monotypic stands of crested wheatgrass (Agropyron cristatum [L] Gaertm. and Agropyron desertorum [Fisch.] Schult.), an introduced grass, occupy vast expanses of the sagebrush steppe. Efforts to improve habitat for sagebrush-associated wildlife by establishing a diverse community of native vegetation in crested wheatgrass stands have largely failed. Instead of concentrating on a diversity of species, we evaluated the potential to restore the foundation species, Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis [Beetle & A. Young] S. L. Welsh), to these communities. We investigated the establishment of Wyoming big sagebrush into six crested wheatgrass stands (sites) by broadcast seeding and planting seedling sagebrush across varying levels of crested wheatgrass control with glyphosate. Planted sagebrush seedlings survived at high rates (∼ 70% planted sagebrush survival 3 yr postplanting), even without crested wheatgrass control. However, most attempts to establish sagebrush by broadcast seeding failed. Only at high levels of crested wheatgrass control did a few sagebrush plants establish from broadcasted seed. Sagebrush density and cover were greater with planting seedlings than broadcast seeding. Sagebrush cover, height, and canopy area were greater at higher levels of crested wheatgrass control. High levels of crested wheatgrass control also created an opportunity for exotic annuals to increase. Crested wheatgrass rapidly recovered after glyphosate control treatments, which suggests multiple treatments may be needed to effectively control crested wheatgrass. Our results suggest that planting sagebrush seedlings can structurally diversify monotypic crested wheatgrass stands to provide habitat for sagebrush-associated wildlife. Though this is not the full diversity of native functional groups representative of the sagebrush steppe, it is a substantial improvement over other efforts that have largely failed to alter these plant communities. We also hypothesize that planting sagebrush seedlings in patches or strips may provide a relatively inexpensive method to facilitate sagebrush recovery across vast landscapes where sagebrush has been lost.

Site, Competition, and Plant Stock Influence Transplant Success of Wyoming Big Sagebrush

Abstract Within the sagebrush steppe ecosystem, sagebrush plants influence a number of ecosystem properties, including nutrient distribution, plant species diversity, soil moisture, and temperature, and provide habitat for a wide variety of wildlife species. Recent increases in frequency and size of wildfires and associated annual grass expansion within the Wyoming big sagebrush alliance have increased the need for effective sagebrush restoration tools and protocols. Our objectives were to quantify the success of Wyoming big sagebrush transplants relative to transplant stock (nursery seedlings vs. wildlings) across different ecological sites and vegetation types and to test the hypothesis that reduction of herbaceous vegetation would increase survival of transplanted sagebrush. We used a randomized block (reps = 5) design at each of three sites—1) cheatgrass dominated, 2) native plant dominated, and 3) crested wheatgrass dominated—near Elko, Nevada. Treatments included plant stock (nursery stock or locally harvested wildlings) and herbicide (glyphosate) to reduce competition from herbaceous vegetation. Transplants were planted in the spring of 2009 and 2010 and monitored for survival. Data were analyzed for site and treatment effects using mixed-model ANOVA. Surviving plant density at and 2 yr postplanting was generally highest (up to 3-fold) on the native site (P < 0.05). Density of surviving transplants was almost 3-fold higher for nursery stock on most sites for the 2009 planting, but differences in survival by planting stock were minimal for the 2010 planting. Glyphosate application increased surviving plant density up to 300% (depending on site) for both years of planting. High labor and plant material investments (relative to traditional drilling or broadcasting) may limit the size of projects for which sagebrush transplants are practical, but these costs may be partially offset by high success relative to traditional methods. Our data indicate that sagebrush transplants can be effective for establishing sagebrush on depleted sites.

Success of Seeding Native Compared with Introduced Perennial Vegetation for Revegetating Medusahead-Invaded Sagebrush Rangeland ☆ ☆☆

ABSTRACT Millions of hectares of Wyoming big sagebrush (Artemisia tridentata Nutt. subsp. wyomingensis Beetle & Young) rangeland have been invaded by medusahead (Taeniatherum caput-medusae [L.] Nevski), an exotic annual grass that degrades wildlife habitat, reduces forage production, and decreases biodiversity. Revegetation of medusahead-invaded sagebrush plant communities is necessary to restore ecosystem services. Disagreement, however, exists over whether to seed native or introduced perennial species to revegetate communities after controlling medusahead. Though native species generally do not establish as well as introduced species, interference from co-seeded introduced species has often been attributed to the limited success of natives. The potential for seeding natives to revegetate communities after medusahead control is relatively unknown because they have been largely co-seeded with introduced species. We compared the results of seeding native and introduced perennial species after controlling medusahead with prescribed burning followed with an imazapic herbicide application at five sites. Perennial bunchgrass cover and density were 5- and 10-fold greater in areas seeded with introduced compared with native species 3 years post seeding. Furthermore, exotic annual grass cover and density were less in areas seeded with introduced compared with native species. Seeded introduced and native shrubs largely failed to establish. High perennial bunchgrass density (15 individuals · m-2) in areas seeded with introduced species in the third year post seeding suggests that the succession trajectory of these communities has shifted to becoming perennial dominated. Average perennial bunchgrass density of 1.5 individuals· m-2 with seeding native species will likely not limit medusahead and appears to already be converting back to exotic annual grass-dominated communities. These results suggest that seeding introduced compared with native species after medusahead control will likely be more successful. Our results also imply that if natives are selected to seed after medusahead control, additional resources may be necessary to recontrol medusahead and repeatedly sow native species.

Variation in Timing of Planting Influences Bluebunch Wheatgrass Demography in an Arid System

Abstract Establishing perennial grasses from seed in postdisturbance Wyoming big sagebrush (Artemesia tridentata subsp. wyomingensis Welsh) communities is often unsuccessful, due in part to a lack of knowledge of the seedling ecology of perennial grasses. We examined the influence of planting timing on germination and seedling demography of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love) in the northern Great Basin. In 2008 (year 1) and 2009 (year 2) we planted seeds monthly, September–December, in 1-m2 plots (500 seeds per plot) using a randomized block design with five replications. Germination timing was indexed using seed bags placed adjacent to 1-m2 plots and retrieved at 2-wk intervals in fall and 1-mo intervals in spring. Seedlings were marked in March–June of the year following planting; seedlings alive in July were considered initially established. Planting in September and October had up to 80% germination prior to winter, whereas December plantings germinated mainly in spring and at reduced rates (15–35%). Seeds planted in September and October emerged approximately a month earlier than November–December plantings. The percentage of germinated seeds that emerged was highest for September–October plantings but the percentage of emergent seeds surviving to the end of the first growing season was highest for later plantings. Final seedling density was lowest for November planting in year 1 and highest for September and October planting in year 2. Our data indicate that timing of and performance at critical stages of seedling development were affected by planting month. We suggest that it may be possible to use emerging technologies (e.g., seed coatings or germplasm manipulations) to produce variable chronologies of seedling development with single plantings and allow managers to exploit multiple temporal windows of opportunity for seedling establishment.

Effects of feral free‐roaming horses on semi‐arid rangeland ecosystems: an example from the sagebrush steppe

Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also a relatively unmanaged, non-native grazer in North America, South America, and Australia. Information about their influence on vegetation and soil characteristics in semi-arid rangelands has been limited by confounding effects of cattle (Bos taurus) grazing and a lack of empirical manipulative studies. We compared vegetation and soil surface characteristics in feral horse grazed areas and ungrazed exclosures at five sagebrush (Artemisia) steppe sites in northern Nevada. Horse grazed areas had lower sagebrush density and plant diversity, greater soil penetration resistance, and lower soil aggregate stability than ungrazed areas. Herbaceous cover and density generally did not differ between grazed and ungrazed treatments, with the exception of heavily grazed sites in which perennial grass cover was reduced. The cumulative effect of feral horses on soil characteristics suggests that they may affect the ecological function of semi-arid rangelands by increasing the risk of soil erosion and potentially decreasing availability of water for plant growth. The two-fold increase in sagebrush density with horse exclusion suggests that feral horses may limit sagebrush recruitment and thereby negatively impact Greater Sage-grouse (Centrocercus urophasianus) and other sagebrush associated wildlife. The effects of feral horses on sagebrush and other semi-arid ecosystems should be considered when developing conservation plans for these ecosystems and associated wildlife.

Winter grazing can reduce wildfire size, intensity and behaviour in a shrub-grassland

An increase in mega-fires and wildfires is a global issue that is expected to become worse with climate change. Fuel treatments are often recommended to moderate behaviour and decrease severity of wildfires; however, the extensive nature of rangelands limits the use of many treatments. Dormant-season grazing has been suggested as a rangeland fuel treatment, but its effects on fire characteristics are generally unknown. We investigated the influence of dormant-season (winter) grazing by cattle (Bos taurus) on fuel characteristics, fire behaviour and area burned in Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) shrub-grassland communities in south-eastern Oregon, USA. Winter grazing was applied for 5 years before burning and compared with ungrazed areas. Winter grazing decreased fine fuels and increased fine fuel moisture, which reduced flame height and depth, rate of spread and area burned. Winter-grazed areas also had lower maximum temperature and heat loading during fires than ungrazed areas, and thereby decreased risk of fire-induced mortality of important herbaceous functional groups. These results suggest that winter grazing may be a fuel management treatment that can be applied across vast shrub-grasslands to decrease wildfire risk and fire intensity to mediate climate change effects on wildfire activity.

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.

Of Grouse and Golden Eggs: Can Ecosystems Be Managed Within a Species-Based Regulatory Framework?

Abstract Declining greater sage-grouse populations are causing concern for the future of this species across the western United States. Major ecosystem issues, including exotic annual grass invasion and conifer encroachment, threaten vast acreages of sagebrush rangeland and are primary threats to sage-grouse. We discuss types of problems facing sage-grouse habitat and argue that complex ecosystem problems may be difficult to address under the Endangered Species Act as currently applied. Some problems, such as anthropogenic development, can be effectively regulated to produce a desired outcome. Other problems that are complex and involve disruption of ecosystem processes cannot be effectively regulated and require ongoing commitment to adaptive management. We believe that historical inertia of the regulatory paradigm is sufficient to skew management toward regulatory mechanisms, even though complex ecosystem problems impact large portions of the sage-grouse range. To overcome this situation, we suggest that the regulatory approach embodied in the Endangered Species Act be expanded to include promoting management trajectories needed to address complex ecosystem problems. This process should begin with state-and-transition models as the basis for a conceptual framework that outlines potential plant communities, their value as sage-grouse habitat, and their ecological status. Desired management trajectories are defined by maintenance of an ecologically resilient state that is of value as sage-grouse habitat, or movement from a less desired to a more desired state. Addressing complex ecosystem problems will involve shifting conservation roles. Under the regulatory approach, programmatic scales define regulatory policies, and local scales focus on implementing those policies. With complex ecosystem problems, programmatic scales empower local conservationists to make decisions necessary to adaptively manage problems. Putting ecosystem management on par with traditional regulatory actions honors obligations to provide regulatory protections while maintaining the capacity of the ecosystem to produce habitat and greatly expands the diversity of stakeholders willing to participate in sage-grouse conservation.