Warming-El Nino-Nitrogen Deposition Experiment (WENNDEx): Soil Nitrogen Data from the Sevilleta National Wildlife Refuge, New Mexico (2006 - 2020)

Humans are creating significant global environmental change, including
shifts in climate, increased nitrogen (N) deposition, and the
facilitation of species invasions. A multi-factorial field experiment
is being performed in an arid grassland within the Sevilleta National
Wildlife Refuge (NWR) to simulate increased nighttime temperature,
higher N deposition, and heightened El Niño frequency (which
increases winter precipitation by an average of 50%). The purpose of
the experiment is to better understand the potential effects of
environmental drivers on grassland community composition, aboveground
net primary production and soil respiration. The focus is on the
response of two dominant grasses (Bouteloua gracilis and B eriopoda),
in an ecotone near their range margins and thus these species may be
particularly susceptible to global environmental change. It is
hypothesized that warmer summer temperatures and increased evaporation
will favor growth of black grama (Bouteloua eriopoda), a desert grass,
but that increased winter precipitation and/or available nitrogen will
favor the growth of blue grama (Bouteloua gracilis), a shortgrass
prairie species. Treatment effects on limiting resources (soil
moisture, nitrogen availability, species abundance, and net primary
production (NPP) are all being measured to determine the interactive
effects of key global change drivers on arid grassland plant community
dynamics and ecosystem processes. On 4 August 2009 lightning ignited a
~3300 ha wildfire that burned through the experiment and its
surroundings. Because desert grassland fires are patchy, not all of
the replicate plots burned in the wildfire. Therefore, seven days
after the wildfire was extinguished, the Sevilleta NWR Fire Crew
thoroughly burned the remaining plots allowing us to assess
experimentally the effects of interactions among multiple global
change presses and a pulse disturbance on post-fire grassland
dynamics. This data set provides soil N availability in each plot of
the warming experiment for the monsoon season (also see SEV176).