Plant traits and ecosystem grazing effects: Comparison of U.S. sagebrush steppe and patagonian steppe

Plant functional traits provide one tool for predicting the effects of grazing on different ecosystems. To test this approach, we compared plant traits and grazing response across analogous climatic gradients in sagebrush steppe, USA (SGBR), known to have a short evolutionary history of grazing, and Patagonian steppe, Argentina (PAT), where generalist herbivores exerted stronger selective pressures. We measured grazing response by sampling vegetation and soils across distance-from-water gradients at arid, semiarid, and subhumid study areas in both regions. Based on a previous analysis of graminoid traits, we predicted that: (1) high forage quality in all three SGBR communities would lead to high utilization and large grazing effects, whereas low quality in arid PAT would constrain utilization and grazing impacts, with semiarid and subhumid PAT intermediate in quality and grazing response; and (2) grazing in arid PAT would cause shifts in relative abundance within the graminoid functional group, due to the...