Ecosystem structure and function across western dryland ecosystems: a cross-site comparison of semiarid ecosystem types in Colorado and Wyoming.

Drylands extend over large portions of the globe, including a significant share of the western United States, yet they remain understudied. We examined ecosystem structure and function at 3 semiarid dryland sites in Colorado and Wyoming, each of which was dominated by a different ecosystem type and plant community—shortgrass steppe, mixed-grass prairie, and sagebrush steppe. This initial study was conducted to fill gaps in knowledge about how sagebrush steppe compares to dryland grasslands in the western United States. Soil respiration was higher at the sagebrush steppe than at the 2 grassland sites (P = 0.001). Aboveground biomass, microbial abundance, and soil inorganic nitrogen were not significantly different among ecosystem types after the 2017 summer season. Soil carbon was largely similar across all ecosystem types down to 5 cm, with more widespread differences among all sites in the 5–10 cm depth. Plant, bacterial, and fungal communities all differ between sites (P < 0.001), though they have large numbers of shared species among the sites. Despite these differences in ecosystem structure between ecosystem types, we found only a single significant difference in ecosystem function: soil respiration was higher at the sagebrush steppe than at the other 2 sites. Given the importance of global drylands, broad and high-powered systematic sampling across dryland types would be beneficial to understanding the extent of similarities and ability to extrapolate across and within dryland ecosystem types. [ABSTRACT FROM AUTHOR]