Warming, El Niño, Nitrogen Deposition Experiment (WENNDEx)

Specifically, we are simulating predicted future environmental conditions with increased nighttime temperatures, N deposition, and El Niño frequency (which increases winter precipitation by 50%, on average, at the Sevilleta). These are all ongoing changes both globally and locally that may influence community composition. We are focusing on the response of two dominant grass species, both of which are near their range margins and may be particularly responsive to the effects of climate change. We hypothesize that warmer summer temperatures and increased evaporation will favor growth of the desert grass black grama (Bouteloua eriopoda), but that increased winter precipitation and/or available nitrogen will favor the growth of the shortgrass prairie grass blue grama (Bouteloua gracilis). Thus, the direct effects of these factors favor different species. Because it is unknown how these factors will interact, the net outcome of these perturbations is not easily predicted.

We are measuring treatment effects (air and soil temperature) on limiting resources (soil moisture, nitrogen availability), species abundance, net primary production and soil CO2 fluxes to determine the interactive effects of three key global change drivers on plant community dynamics and ecosystem processes in this desert grassland ecotone.