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DIFFERENTIATION IN N15 UPTAKE AND THE ORGANIZATION OF AN ARCTIC TUNDRA PLANT COMMUNITY
Citation:
McKane, R B., L. C. Johnson, G. R. Shaver, K. Nadelhoffer, E. Rastetter, A. E. Giblin, AND B. Fry. DIFFERENTIATION IN N15 UPTAKE AND THE ORGANIZATION OF AN ARCTIC TUNDRA PLANT COMMUNITY. Presented at Ecological Society of America, Snowbird, UT, August 6-10, 2000.
Description:
We used N15 soil-labeling techniques to examine how the dominant species in a N-limited, tussock tundra plant community partitioned soil N, and how such partitioning may contribute to community organization. The five most abundant species were well differentiated with respect to the chemical form (ammonium, nitrate and glycine), season (June and August), and/or depth (3 and 8 cm) of N uptake. Species abundance was positively correlated with the similarity between the uptake and availability of native forms of N, suggesting that competition and resource partitioning have strongly influenced the organization of this community. We are further investigating this hypothesis by examining the degree of spatial overlap among species that are similar or dissimilar in their use of N. Uptake of N15 injected at different distances from individual plants shows significant interspecific differences in horizontal rooting areas and a high potential for overlap of rooting areas among species. Additional data describing the distances among neighboring plants will be needed to calculate the actual overlap of species' rooting areas and how that may be related to the degree of ecological overlap measured by N15 partitioning.