Shifts in sage-grouse arthropod food sources across grazing and environmental gradients in upland meadow communities

Authors: RICHARDSON, WILLIAM - University Of Nevada; STRINGHAM, TAMZEN - University Of Nevada; NUSS, ANDREW - University Of Nevada; MORRA, BRIAN - University Of Nevada; Snyder, Keirith

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2023
Publication Date: 10/14/2023
Citation: Richardson, W., Stringham, T.K., Nuss, A.B., Morra, B., Snyder, K.A. 2023. Shifts in sage-grouse arthropod food sources across grazing and environmental gradients in upland meadow communities. Arthropod-Plant Interactions. 119261. https://doi.org/10.1016/j.jenvman.2023.119261.
DOI: https://doi.org/10.1016/j.jenvman.2023.119261

Interpretive Summary: Groundwater dependent systems, such as meadows, are extremely important habitats for a wide variety of plants and animals in the Great Basin of North America. The impacts of cattle and wild horse grazing on these habitats can cause shifts in the timing and availability of plant species that are important food sources for livestock and wildlife. In addition grazing may affect arthropod (e.g. insects) composition and abundance. The Greater sage-grouse, a keystone species of Great Basin ecosystems, rear brood in these areas during spring and summer months, and eat both plant forb species and arthropods. To examine the impact of grazing on these ecosystems, seven meadows, each consisting of three distinct vegetative communities, were grazed at three intensities across two years (2019-2020) to determine the relationship between grazing management, environmental variables, and abundance levels of arthropods during peak sage-grouse utilization periods. Additionally, the agreement of on-the-ground measurements and near-surface digital cameras (phenocams) was examined to understand how remote sensing technologies can be used to monitor these insect abundance shifts on larger scales. Understanding how changes in grazing affects plants, insects, and the wildlife species that depend upon these resources, helps land managers conserve and restore critical habitat for keystone species.

Technical Abstract: Groundwater dependent systems are extremely important habitats for a wide variety of taxa in the Great Basin of North America. The impacts of grazing on these habitats causes shifts in resources and subsequent change in species composition. The Greater sage-grouse, a keystone species of Great Basin ecosystems, rear brood in these areas during spring and summer months, utilizing forb and arthropod groups. To examine the impact of grazing on these ecosystems, seven meadows, each consisting of three distinct vegetative communities, were grazed at three intensities across two years (2019-2020) to determine the relationship between grazing management, environmental variables, and abundance levels of arthropods during peak sage-grouse utilization periods. Additionally, the agreement of on-the-ground measurements and near-surface digital cameras (phenocams) was examined to better understand how remote sensing technologies can be used to monitor these insect abundance shifts on larger scales. Arthropod taxa abundance responded differently to grazing management and environmental variables. Coleoptera abundance during peak sage-grouse usage periods had an increase of roughly 40% in some meadows with increased grazing intensity, while Formicidae abundance saw a 22% decrease. For year-to-year environmental variability in precipitation, Lepidoptera abundance was 115% higher in the drier year, while Coleoptera was 64% lower. Near-surface cameras had varied success with predicting peak insect abundance levels. Lepidoptera and Coleoptera capture rates had strong correlations with phenological indices derived from phenocams, while Formicidae had much weaker relationships.