Mary M. Rowland

ELK DISTRIBUTION AND MODELING IN RELATION TO ROADS

We tested performance of 3 aspects of an elk (Cervus elaphus)-road density model that has been used extensively throughout western North America but has not been sufficiently validated. First, we tested the hypothesis that elk selection of habitats increases with increasing distance away from open roads. This forms the empirical basis for the model. Second, we compared the models predictions of relative elk habitat selection, or habitat effectiveness (HE), with observed values at varying levels of road density. And third, we examined the potentially confounding effects of different spatial patterns of roads on model predictions. We conducted our study during spring and summer, 1993-95, at the Starkey Experimental Forest and Range (Starkey), northeast Oregon. Selection ratios were calculated using >100,000 recorded locations of 89 radiocollared female elk, with locations mapped in relation to 0.1-km-wide distance bands away from open roads. Selection ratios increased with increasing distance from open roads, and varied between seasons, but not among years or individual animals. Linear regression models, using distance to open roads as a predictor, accounted for significant variation in selection ratios during spring and summer. Model predictions of HE, as measured by number of elk locations, corresponded only weakly, however, with observed values of HE. The contradictory results of these 2 analyses may be explained in part by our simulation results, which showed that potential reductions in elk HE vary strongly with the spatial pattern of roads, which is not measured by the elk-road density model. Our results suggest that (1) management of roads and related human activities during spring and summer should remain an important consideration for modeling and managing the elk resource; and (2) a spatially explicit road component is needed for elk habitat models.

Influence of grazing management on resource selection by a small mammal in a temperate desert of South America

Drylands occupy almost 50% of the Earths surface and are increasingly affected by extensive land uses such as grazing. These practices affect multiple biotic and abiotic interactions mainly through loss of habitat and resources available for native wildlife. We examined the effects of local vegetation conditions on resource selection by a small mammal species in drylands with different resource availability. The study was conducted in a semi-arid woodland that included an area protected from livestock grazing and human settlement for more than 50 years, the Man and the Biosphere Ñacunán Reserve, and an adjoining area that has experienced long-term cattle grazing. We tracked radio-collared individuals of Graomys griseoflavus, the most abundant small mammal in the Ñacunán region, and calculated resource selection functions (RSFs) to evaluate habitat selection. We modeled resource selection using a suite of habitat variables measured in both areas. We hypothesized that long-term changes in vegetation associated with livestock grazing would substantially influence habitat selection. G. griseoflavus selected vegetation patches with relatively greater cover of forage species (i.e., taxa commonly consumed) and avoided open spaces; they also selected sites with greater species richness and cover of grasses and trees. Although resource selection patterns were generally similar under both management conditions (i.e., under passive restoration and grazing), the strength of selection was greater in the grazed area. The final RSF model validated well with k-fold cross-validation (R2 = 0.61). Because of the importance of rodents in ecosystem function, management to meet their resource requirements could be an important tool for habitat restoration in degraded drylands.

Diet Overlap of Mammalian Herbivores and Native Bees: Implications for Managing Co-occurring Grazers and Pollinators

ABSTRACT: Many federal, state, and tribal agencies, as well as nonprofit organizations, have recently increased efforts to understand how natural areas can be managed to enhance native pollinators and the ecosystem services they provide. However, managing this important group must be balanced with other services that natural areas provide including hunting, timber production, and livestock grazing. Significant knowledge gaps exist about how to effectively manage habitats used by large ungulates (e.g., cattle (Bos taurus), elk (Cervus elaphus), mule deer (Odocoileus hemionus)) in ways that also enhance pollinators. One key gap is understanding the degree to which diets of mammalian herbivores overlap with floral resources used by bees, and how this overlap varies spatially and temporally. Invertebrate pollinators, including bees, rely on flowering forbs and shrubs for nectar and pollen. Ungulates also feed on flowering plants, although preferences vary by ungulate species, vegetation community, and season. Here we review existing literature on ungulate diets relative to flowering plants and compare this information with flower preferences of bees, drawing on studies of bee abundance and diversity at the Starkey Experimental Forest and Range in northeastern Oregon. Our review can inform managers about the potential dietary overlap between ungulates and native bees and aid planning efforts aimed at biodiversity conservation of pollinators. We discuss management implications relative to seasonal habitat use and dietary preferences of ungulates and variation in bee phenology, and conclude with guidance about timing and intensity of ungulate grazing when managing for multiple conservation objectives, especially in sensitive habitats like riparian areas.

Cattle grazing in semiarid forestlands: Habitat selection during periods of drought

Climate change models are predicting increased frequency and severity of droughts in arid and semiarid environments, and these areas are responsible for much of the worlds livestock production. Because cattle (Bos Taurus) grazing can impact the abundance, distribution, and ecological function of native plant and animal communities, it is important to understand how cattle might respond to increasingly arid conditions. Here, we evaluate changes in habitat selection by cattle across an 8-yr period as a function of rainfall and other environmental covariates. Using resource selection functions, we evaluated habitat selection based on 2 behaviors, stationary and mobile. Models revealed similarity in cattle habitat selection across years, with only modest changes in selection as a function of precipitation, despite marked seasonal and interannual differences in rainfall. Cattle preferred gentle slopes, forest edges, wet meadows, and areas near water as well as areas far from water on plateaus. Cattle avoided areas at intermediate distances from water, typically associated with steep slopes. As conditions became drier during the late season, cattle did not switch selection patterns but instead contracted their selection around water. Cattle also selected similar habitats whether they were mobile or stationary, possibly making microsite decisions therein. This consistent pattern of selection across years could be particularly problematic for riparian communities as climates become drier; however, it may also simplify cattle management, as range managers can focus vegetation monitoring efforts on riparian areas. Due to the uncertainty surrounding future climatic conditions, it is imperative that both range and wildlife managers develop long-term plans to continue managing these multiuse landscapes in an ecologically sustainable manner based on expected patterns of livestock grazing.

Associations Between Blooming Plants and their Bee Visitors in a Riparian Ecosystem in Eastern Oregon

Abstract Native bees are declining worldwide, but conserving or restoring their habitat requires a better understanding of bee-flower associations. High quality bee habitat includes flowers that provide pollen and nectar preferred by bees. However, little data exist about which plants are commonly used by bees in the Pacific Northwest, or whether bees prefer certain plant characteristics over others. We examined bee and plant communities in an Oregon riparian ecosystem. Our purpose was to describe bee-plant associations, determine which plants are most frequently visited by bees, identify plants that may be preferred by bees, and examine how a plants native status, flower color, and floral morphology affect the types of bees visiting it. We found that many blooming plants received a diverse set of bee visitors, but some plants had a higher number and species richness of visiting bees than others. No plant species seemed limited to visitation by a small set of specialist bees. The number and type of visiting bees were not influenced by the plants native status. However, flower morphology (but not color) significantly affected types of bees visiting plants. Bilaterally symmetrical and medium tubular flowers, with nectar and pollen typically more difficult to reach, were associated with larger bees with longer tongues, while smaller, easily accessible flowers attracted smaller bees with shorter tongues. Our results suggest that certain plants are particularly useful for supporting abundant and diverse bee communities, and increasing diversity in the morphology of blooming plants is a key factor to consider when restoring riparian areas for bee pollinators.

Data and analyses of woody restoration planting survival and growth as a function of wild ungulate herbivory

These data and analyses support the research article “Wild ungulate herbivory suppresses deciduous woody plant establishment following salmonid stream restoration” Averett et al. (2017) [1]. The data and analyses presented here include: (1) planting density, survival and growth (two years post restoration) of riparian plantings along an ~11 km stream reach in northeastern Oregon as a function of herbivory treatment (protected/not protected from wild ungulate herbivory), habitat type, and planting species; and (2) abundance and height distributions of naturally occurring deciduous woody species along the restored stream reach two years post restoration. Survival and growth analyses are provided as output from multiple logistic and mixed effect regression models respectively.