Vegetation structure at greater sage-grouse (Centrocercus urophasianus) nesting habitat has been documented to be important to nest success. To effectively conserve declining sage-grouse populations, managers should understand vegetation structure across a large spatial scale. Ecological sites are a land management unit used by federal agencies that describe landscape variation in soil, hydrologic and topographic factors and vegetation communities. We assess the utility of using ecological sites to manage nesting habitat by 1) evaluating which vegetation structural characteristics differ among ecological sites and 2) examining which characteristics have implications for nest success. We also evaluate if vegetation structural patterns change at different scales from 0 to 15 meters from the nest. We sampled vegetation structure at 97 nests and 15 paired random plots across a 135,000-hectare area in Southwestern Wyoming. At each plot, we measured horizontal and vertical structure, species composition and shrub density along two, 30-meter perpendicular transects that intersected at the nest or random shrub. We explore differences in vegetation structure and composition among ecological sites, between nest and random sites and at successful and unsuccessful nests using univariate comparison tests and two multivariate approaches, linear discriminant analysis and MANOVA.
Results/Conclusions
Intercanopy space, big sagebrush cover, grass cover and vegetation height within 5 meters of the nest differentiated ecological sites (MANOVA, p =0.007). Shrub density was lower on successful nest sites (p= 0.004). Horizontal structure transitions from small gaps in canopy near the nests to larger canopy gaps beyond 5 m from the nests (p = 0.03). Structural variables differ among ecological sites suggesting that ecological sites differ in nesting habitat quality. Structural changes at greater distances from the nest have implications for monitoring greater sage-grouse nesting habitat.