Data from: Nitrogen addition pulse has minimal effect in big sagebrush (Artemisia tridentata) communities on the Pinedale Anticline, Wyoming (USA)

Nitrogen additions are known to elicit variable responses in semi-arid
ecosystems, with responses increasing with precipitation. The response of
semi-arid ecosystems to nitrogen are important to understand due to their
large spatial extent worldwide and the global trend of increasingly
available nitrogen. In this study, we evaluated the impact of a single
nitrogen addition pulse on a semi-arid big sagebrush (Artemisia
tridentata) ecosystem in western Wyoming. This is important given that
sagebrush ecosystems are poorly understood, despite their prevalence in
the western US. In addition, large-scale nitrogen additions have begun on
sagebrush landscapes in Wyoming in order to mitigate population declines
in mule deer (Odocoileus hemionus). The study objectives were (1) to
evaluate the effectiveness of a nitrogen fertilization pulse in increasing
sagebrush biomass and forage quality, and (2) to assess effects of
nitrogen addition on soil biogeochemistry and vegetation community
structure. We fertilized 15 plots across 5 locations in western Wyoming
using a single pulse of urea (5.47g N m-2). In addition, we immobilized
available nitrogen through surface hay treatments (254g hay/m2). Nitrogen
additions failed to increase growth of sagebrush, alter nitrogen content
of sagebrush leaders, or alter greenhouse gas efflux from soils. The plant
community also remained unchanged; total cover, species richness, and
community composition were all unaffected by our treatment application.
Over the two years of this study, we did not find indications of nitrogen
limitation of ecosystem processes, despite a wet growing season in 2014.
Thus, we have found a general lack of response to nitrogen in sagebrush
ecosystems and no treatment effect of a single pulse of N to sagebrush
biomass or forage quality.