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In the Yukon-Kuskokwim (YK) Delta, geese create grazing lawns in Carex subspathacea meadows. Geese annually maintain the grazing lawns, resulting in different aboveground morphological expressions for grazed Carex subspathacea compared to ungrazed Carex subspathacea. Grazed C. subspathacea tends to grow to an average of 1.5 centimeters (cm) in height and has a floret growth form, while ungrazed C. subspathacea reaches an average height of nearly 15.5 cm. Additionally, grazed C. subspathacea has lower Carbon : Nitrogen (C:N) content than ungrazed C. subspathacea. Furthermore, both the physical alterations to Carex subspathacea and the changes to the soil physiochemical environment caused by grazing suggest that aboveground herbivory may affect root trait expression of C. subspathacea, which in turn may influence biogeochemical processes such as soil respiration and decomposition rates. This data set contains information on Carex subspathacea root traits, including root morphology (total length, surface area, and volume), root exudates (dissolved organic carbon concentration), and root chemistry (carbon, nitrogen, phosphorus, lignin, cellulose, and acid fiber detergent) collected in Western Alaska's Yukon-Kuskokwim's delta. The samples were collected from two Carex subspathacea habitat types (grazed or ungrazed). 

Abstract Understanding environmental drivers of species diversity has become increasingly important under climate change. Different trophic groups (predators, omnivores and herbivores) interact with their environments in fundamentally different ways and may therefore be influenced by different environmental drivers. Using random forest models, we identified drivers of terrestrial mammals' total and proportional species richness within trophic groups at a global scale. Precipitation seasonality was the most important predictor of richness for all trophic groups. Richness peaked at intermediate precipitation seasonality, indicating that moderate levels of environmental heterogeneity promote mammal richness. Gross primary production (GPP) was the most important correlate of the relative contribution of each trophic group to total species richness. The strong relationship with GPP demonstrates that basal‐level resource availability influences how diversity is structured among trophic groups. Our findings suggest that environmental characteristics that influence resource temporal variability and abundance are important predictors of terrestrial mammal richness at a global scale.