![]() |
Main Menu | Search | CD Help | Access the Technical Program
Note: Program subject to change without notice
Atmospheric N deposition is becoming a stressor on ecosystems in the western U.S. There are few NADP monitoring sites and little is known about N deposition impacts on terrestrial ecosystems. High elevation ecosystems (i.e. above 2895 m) may be particularly sensitive to N-induced changes due to shallow soils, short growing seasons, and sparse plant cover. This study focuses on N deposition effects on a high elevation ecosystem along a modeled deposition gradient and across contrasting edaphic conditions in the Grand Teton National Park. For 3 locations, we measured N input (snow pack surveys, and summer deposition via through fall resin collectors set out for 40-90 days), soil parameters (total and extractable N, microbial biomass, and nitrification potential), and plant community characteristics (species richness, species composition, percent cover, plant and root biomass, and N in plants) to test whether soils or plants are effected by N deposition first. Preliminary results show that inorganic N input via snow ranged from 1-2 kg N ha-¹ with slightly more entering into the system as NH4-N. Summer deposition (~0.5 kg N ha-¹) did not differ among sites. Total and extractable N ranged from 0-10 µg g-¹ and failed to follow the modeled deposition regime. However, nitrification potential followed the modeled regime. For low N deposition sites, wet conditions favored nitrification potential, while for high N deposition sites, nitrification potential occurred in drier sites. Regression analysis suggested that species richness was not affected by either N input, or N already in the system.