ACCUMULATION AND USE OF NITROGEN AND PHOSPHORUS FOLLOWING FERTILIZATION IN 2 ALPINE TUNDRA COMMUNITIES

To determine whether there are differences in the relative capacity of communities to accumulate nutrients and translate nutrient uptake int o growth, N and P standing crops and use efficiencies were measured fo llowing fertilization in two alpine tundra communities. In general, di fferences in nutrient dynamics between the communities corresponded wi th the type and degree of nutrient limitation of production. The N-lim ited dry meadow had greater increases in aboveground N standing crop a nd tissue N concentration in response to N fertilization, higher N-use efficiency, and higher N resorption than the wet meadow. Conversely t he N-P co-limited wet meadow had a greater P accumulation response to P fertilization and higher P-use efficiency than the dry meadow. Diffe rences in the response to the treatments and in nutrient use efficienc ies were mediated largely by individual plant growth forms. Although t here was a substantial amount of luxury consumption of N and P, there was evidence of coregulated uptake relative to the availability of the se nutrients in the soil.