Carlsbad Caverns National Park is currently experiencing increased levels of N-deposition resulting from oil and gas wells in the areas immediately adjacent to the park. There have been few studies on the effects of N-deposition in dryland regions, with very little knowledge about the effects in the northern Chihuahuan desert. The research team will use a manipulative fertilization experiment to assess the ecosystem consequences of increased deposition to: 1) determine at what level of N-addition they begin to observe consequences on vegetation composition and coupled biogeochemical cycles (i.e., Critical Load), and 2) determine whether N-addition affects abundance of invasive grasses.