Nutrient stoichiometry of three plant species under a natural nutrient gradient of a semiarid small watershed

Abstract

Current understanding of plant nutrient stoichiometry mainly focus on C, N, and P and in humid and tropic regions. This study was conducted to investigate nutrient stoichiometry in a semaird small watershed. Three dominant plants, Medicago sativa, Stipa bungeana, and Artemisia sacrorum, sampled along a natural nutrient gradient, were analyzed with respect to plant nutrient stoichiometry (N:P, N:K, and K:P). The results showed that nutrient stoichiometry varied greatly between plants and within the same plant at the small watershed scale. At the natural nutrient gradient, N:P of the N limited plant is mainly determined by plant N, while that of P or P+N limited plants were dominated by plant P. The N:K and K:P of both N limited and P or N+P limited plants were mainly controlled by plant K with weak relations to nutrient limitations. Aboveground biomass directly influences nutrient stoichiometry, while extractable soil nutrients exert their impacts on stoichiometry through aboveground biomass.