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 into growth, N and P standing crops and use efficiencies were measured following fertilization in two alpine tundra communities. In general, differences in nutrient dynamics between the communities corresponded with the type and degree of nutrient limitation of production. The N-limited dry meadow had greater increases in aboveground N standing crop and tissue N concentration in response to N fertilization, higher N-use efficiency, and higher N resorption than the wet meadow. Conversely the N-P co-limited wet meadow had a greater P accumulation response to P fertilization and higher P-use efficiency than the dry meadow. Differences in the response to the treatments and in nutrient use efficiencies were mediated largely by individual plant growth forms. Although there was a substantial amount of luxury consumption of N and P, there was evidence of coregulated uptake relative to the availability of these nutrients in the soil.