Habitat Ecology & Management II

Contributed Oral

 
Associations between Public Lands Cattle Grazing and Long-Term Trends in Vegetation
Christopher Hansen, Joshua J. Millspaugh, Brady Allred

Livestock grazing is a common practice on public lands in the western United States, which has caused considerable controversy, given grazing may negatively affect ecosystem function. However, the effects of grazing are likely complex, with factors such as grazing intensity and abiotic variation driving responses. It is largely unknown how grazing on public lands has affected rangelands. Thus, our primary objective was to identify whether grazing practices were associated with changes in vegetation cover and primary productivity on public lands over the past 35 years. To address this objective, we acquired billed Animal Unit Month (AUM) data as an indicator of livestock grazing intensity for 12,628 Bureau of Land Management (BLM) grazing allotments for the past 30-35 years from the Rangeland Administrative System. We also acquired annual vegetation functional group cover and above-ground biomass data for each BLM grazing allotment using the Rangeland Analysis Platform. We fit linear mixed effects models with annual change and 35-year trends in functional group vegetation biomass as response variables; grazing intensity (AUM/ha), precipitation, and temperature as fixed effects; and allotment as a random effect. Annual changes in precipitation had the strongest positive association with annual change in perennial and annual forb and grass biomass. Trends in precipitation and temperature also had the strongest effects on trends in perennial and annual forb and grass biomass, with allotments that got warmer and drier over time having the largest decreases in vegetation biomass and cover. Grazing intensity had weak to no associations with annual changes or 35-year trends in vegetation. Our results suggest that current cattle grazing practices on BLM allotments were not strongly associated with annual vegetation change or vegetation trends for the past 35 years, when considering allotment-scale effects across the range.

 
Impacts of Conifer Removal on Sagebrush Songbirds
Elise Zarri, Thomas Martin

Conifers are encroaching into sagebrush habitats across the western United States, contributing to habitat loss and degradation for sagebrush associated species. Conifer removal is a common restoration technique and is often implemented to improve habitat quality for Greater Sage-Grouse. Benefits of tree removal to sage-grouse have been well studied and sage-grouse populations increase without trees on the landscape. Other sagebrush associated species are assumed to benefit similarly, but these assumptions are rarely tested. Understanding how habitat modifications, such as conifer removal impact all species in the community is essential for informed management. This study investigates the impacts of conifer removal on the abundance and reproductive success of sagebrush songbirds, including sagebrush-obligate, sagebrush-associated, and generalist species. Removal of conifers could result in ecological traps for songbirds due to high spillover nest predation from conifer habitats. I monitored nests and mapped territories of seven songbird species between conifer removal and control areas in montane sagebrush habitat in southwest Montana. Sagebrush-obligate species including Brewer’s Sparrow and Sage Thrasher are more abundant and have higher nest success in conifer removal areas. Sagebrush-associated and generalist species show mixed responses. Vesper Sparrows are more abundant in removal areas, whereas Green-tailed Towhees, Dark-eyed Juncos, Chipping Sparrows, and White-crowned Sparrows are more abundant where conifers remain. Additional data is required to clarify patterns of nest success for these species. However, initial results indicate that conifer removal is beneficial for declining species of sagebrush-obligate songbirds.

 
Managing Caribou Based on Decline and Recovery of Lichen Communities in Southwestern Alaska
Patrick Walsh, Andy Aderman

Lichens are generally the single most important winter diet component for barren ground caribou and reindeer (both referred to here as caribou).  Lichens are characterized by an extremely slow rate of growth compared to vascular plants, and in response to this, caribou often demonstrate a migratory lifestyle, and periodically undergo major range shifts.  This presents challenges to caribou managers, particularly when the object of management is to maintain caribou in a given area.  Our objectives are to present results of lichen monitoring studies on two separate caribou ranges on Togiak National Wildlife Refuge, southwestern Alaska and discuss their management applications. Both studies included human-established non-migratory caribou herds—one being an island population (Hagemeister Island) and the second being a mainland population (Nushagak Peninsula).  The Hagemeister Island population was established by translocation in 1965, increased to over 1,000, overgrazed the existing lichen, and underwent a starvation-dieoff that was followed by removal of the surviving caribou in 1993 by managers.  Following caribou removal, lichen biomass increased from ~504 kg/ha in 2003 to ~795 in 2015.  We estimate time to recovery with three competing growth curves which estimate grazeable biomass may be reached in 34-41 years but recovery to climax biomass is estimated to require a minimum of 71 years.  The Nushagak Peninsula caribou population was established by translocation in 1988, increased to >1,400 caribou, and has undergone cyclic population fluctuations since then.  Lichen cover is declining, changing from 48-30% cover from 2002-2017.  In response to the lichen decline, we have reduced caribou population size through increased human harvest, and currently attempt to maintain the population below 600 caribou.  This is an experimental effort, and we recognize the likelihood that the range will continue to decline in value to caribou, and that caribou may ultimately shift to a new range.

 
Winter Foraging Relationships of Bats on Working Forests in the Southeastern US Coastal Plain Using Occupancy Models
Santiago Perea, Steven Castleberry, Angela Larsen-Gray, Daniel Greene

Insectivorous bats in temperate zones have evolved strategies, such as migration or hibernation, to face challenges of reduced resource availability and increased energy demand during winter. In the southeastern U.S. Coastal Plain, many bats are year-round residents and remain active during the winter or migrate from colder areas seeking milder conditions. Southeastern Coastal Plain forests may represent important areas for remnant populations of bat species impacted by white-nose syndrome (WNS). However, winter habitat use by these remnant populations of bat species impacted by white-nose syndrome (WNS). However, winter habitat use by these bats remains understudied. Therefore, our goal is to evaluate factors influencing winter activity and foraging habitat of bats on working forests in the southeastern U.S. Coastal Plain. From January to March 2020-21, we deployed Anabat Swift acoustic detectors to record bat calls and measured temperature and vegetation structure in loblolly pine (Pinus taeda) stands in Georgia (n = 42), Louisiana (n = 40), South Carolina (n = 41), and Mississippi (n = 41). We recorded 7 individual species and 2 species groups. Preliminary results suggest temperature is strongly correlated with winter bat activity. By providing baseline information on winter bat communities and foraging habitat associations, our results will inform managers of habitat features important to wintering bats, including those affected by WNS, when planning forest management activities, and thus increase conservation opportunities within working forests.

 
White-Tailed Deer Harvest Success and Its Impact on Forest Understory Vegetation: Evaluating Management Program Efficacy in Southeastern New York
Ralph Green, Danielle Begley-Miller

In southeastern New York, white-tailed deer (Odocoileus virginianus) populations have increased over the last 50 years from a lack of natural predation, increase in food resources from land use changes, and restrictive hunting regulations. Unmanaged deer populations have severe negative impacts on understory plant communities, a key contributor to forest regeneration and biodiversity, affecting other plant and animal species. Numerous strategies are employed by land managers throughout the Hudson Valley region of New York to manage deer via lethal means. This study aims to better understand the effectiveness of different white-tailed deer removal programs (i.e., culling, archery, and firearms seasons) compared to no management in improving forest understory conditions across 7 nature preserves in the Hudson Valley. An analysis of variance found that deer density estimates decreased or stabilized across all program types in the first 4 years of management (F(4,18) = 2.3, p = 0.098), and harvest efficiency (number of deer harvested per hour effort) decreased at all sites with time (F(3,23) = 8.974, p < 0.001). Culling (5.32 deer/per hour) was the most efficient harvest strategy compared to archery (0.22 deer/per hour) and firearms (0.02 deer/per hour) programs. While management programs did reduce deer densities, an analysis of covariance found that those changes did not correlate consistently with seedling density (F(1,16) = 0.483, p = 0.49), and seedling height (F(1,13) = 1.131, p = 0.72), but did positively correlate with understory diversity (F(1,43) = 11.184, p = 0.002). Vegetation responses appear site-specific and driven by additional site limitations beyond deer density, but data analysis was limited by inconsistent data collection strategies across sites. We recommend regional coordination among land managers to establish consistent protocols to assess and monitor the impacts of deer density on local forested ecosystems prior to starting a deer management program.

 
Arid Lands Restoration Toolbelt: How to Get Native Plants to Grow When It Won’t Rain
Helen Rowe, Tiffany Sprague, Anita Antoninka, Becky Ball, Jane Brady, Mary Fastiggi, Dan Gruber, Debbie Langenfeld, Lisa Rivera

Ecological restoration is a promising way to improve ecological function, habitat connectivity, and aesthetic values for recreation. However, effective restoration practices for arid environments remain elusive. To help fill this knowledge gap, we tested combinations of common and novel restoration techniques in the Sonoran Desert, Arizona, U.S.A. Treatments included surface modifications, such as ripping soils; seed mixtures, including adding native seed bank topsoils; seeding timing; cactus transplants; and soil crust harvest and reintroduction. Ripping had the desired effect of decreasing soil bulk density and increasing infiltration and water-holding capacity, but non-native plant cover increased and native cover decreased in ripped areas over time. Seed mixtures performed best when planted before the winter rains compared to before the summer monsoon, but less than half of the seeded species persisted across years. The seed bank topsoil application was most effective at increasing native species richness in the first year. Cactus transplants established well but did not appear to aid establishment of other plants. Soil crusts can be successfully salvaged, cultivated, and reintroduced. Psyllium helped bind the biocrusts to the soil to improve establishment, and jute helped reduce non-native plant growth. Removal of disturbances is one of the most important factors in restoring degraded areas; even untreated sites had similar levels of plant cover and richness as nearby undisturbed areas after several years. Results from these projects can provide managers with a suite of tools to successfully restore arid lands and improve habitat quality and connectivity.

 
Personality Structure and the Movement Behavior of An Ecosystem Engineer, Dipodomys spectabilis, Following Landscape Restoration
Casey Wagnon, Robert Schooley, Bradley Cosentino

Quantifying animal personality and dispersal syndromes should provide insights into drivers and constraints contributing to the colonization success of restored habitats. Grasslands in the Chihuahuan Desert of the southwestern United States are threatened with shrub encroachment, prompting landscape-scale restoration efforts to remove shrubs and improve habitat conditions for grassland species. We evaluated whether personality structure and the movement behavior of a keystone rodent (banner-tailed kangaroo rats, Dipodomys spectabilis) of Chihuahuan desert grasslands contributes to the colonization dynamics of restored habitats. We sampled individuals from 3 grassland restoration sites and 2 remnant grasslands across a broad region in southern New Mexico, U.S.A. We combined movement experiments using artificial shrubs with repeated behavioral assays to examine if and how stable individual differences in behavioral traits predict movement behavior. We also examine whether personality structure and movement behavior differ between populations from remnant grasslands and restored habitats. Mixed-effects models revealed stable individual differences for 5 of 6 behaviors measured. Moreover, D.spectabilis exhibited stable individual differences in movement behavior, but it did not differ between remnant and restored habitats. However, bolder and more active individuals tended to move through movement assays quicker. We discuss the implications of personality structure and the movement behavior of an ecosystem engineer in the context of habitat restoration.

 
Long-Term Effects of Adaptive Management on Mule Deer Wintering Habitat in Eastern Oregon
Jacob Dittel, Dana Sanchez, Lisa Ellsworth, Connor Morozumi, Ricardo Mata-Gonzalez

Fire has played a crucial role in shaping the sagebrush steppe ecosystem. However, historically recent changes on the landscape have negatively altered fire response in the sage-steppe. Within the Phillip W. Schneider Wildlife Area (PWSWA) in eastern Oregon these changes in the sage-steppe ecosystem are thought to have led to significant drops in mule deer (Odocoileus virginianus) populations due to loss of suitable wintering habitat. Since 2012 we have been characterizing the effects of Oregon Department of Fish and Wildlife’s (ODFW) habitat restoration efforts at two sites within PWSWA. The project’s initial goal was to monitor the effects of juniper removal and cattle exclusion treatments within the basin, however in 2014 a wildfire burned through the study area and ODFW started herbicide treatments for invasive grasses and seeding of native species. To assess the efficacy of all treatments we conducted annual vegetation surveys within one-hectare plots in 2012 and 2014 – 2020. We recorded the percent cover of grasses (invasive and native and/or seeded), forbs, and shrubs using line transects. We also enumerated grass and forb biomass on each plot within 1 m2 subplots. Data from 2012 was used as a pre-fire baseline and we compared pre-fire juniper removal and herbicide treatments amongst years and sites. We found that pre-fire juniper removal had no effect on the trajectory of sites post-fire in the amount of exotic grass, native grasses, nor forbs. Fire and herbicide treatments caused immediate decreases in exotic grass biomass and percent cover but they returned to pre-treatment levels within 3 years. Native grasses, forbs, and shrubs have increased in percent cover and biomass since the fire and have exceeded pre-fire cover since 2017. These data suggest that while exotic grass mitigation may require repeated treatments, improvements in mule deer habitat can be achieved.

Contributed Oral
Location: Virtual Date: November 3, 2021 Time: 2:00 pm - 3:00 pm