Simulated responses of big sagebrush ecosystems to increased precipitation intensity in the western United States

Simulated responses of big sagebrush ecosystems to increased precipitation intensity. Here we use an individual plant-based ecohydrological model (STEPWAT2) to simulate water cycling and shrub, grass, and forb growth for 200 sites across the western United States, and test the effects of simulations conducted with 25%, 50% and 100% increases in precipitation event sizes without changing annual precipitation amounts. Simulations were also performed for 3 °C and 5 °C warming, and four soil textures. The files included in this repository are summarized output from model simulations. The include mean biomass responses for each sites (and treatment combination). Additionally, for each site and treatment values of numerous ecohydrological values are provided (e.g. transpiration, drainage, evaporation). Where relevant these include values for each of 8 soil layers. In the case of transpiration, values for are also provided for each plant functional type. 

Analyses using these data show that: Precipitation intensification generally increased shrub growth in arid and semi-arid sites, but not mesic sites, by decreasing evaporation and ‘pushing’ water deeper into the soil. This effect partially counteracted the mostly negative effects of warming on shrub growth. In contrast, forbs and grasses did not exhibit consistent responses to precipitation intensification. Overall precipitation intensification provided a competitive advantage to shrub growth under a wide range of aridity, soil textures, and temperatures and can be expected to contribute to the woody plant encroachment that has been observed around the world in the past 50 years.