VARIATION PATTERN AND INTERACTION OF LEAF STOICHIOMETRY WITH SLOPE ASPECT IN THE CENTRAL QILIAN MOUNTAINS, NORTHWEST CHINA

Arising from differences in water, nutrient and energy balances, variations in leaf stoichiometry are complex interactions with slope aspect. The leaf stoichiometry of the dominant plant species growing on south-facing (SFS), south-west-facing (SWS), north-west-facing (NWS), and north-facing (NFS) slopes situated in the central Qilian Mountains of northwest China, was documented at the individual species, taxonomic family, and community levels. Leaf stoichiometry was species-specific, and each varied significantly. However, leaf stoichiometry for species shared by all slope aspects, the variation in stoichiometry of some species was homeostatic. Both at the family and community levels, slope aspect had a complex effect on leaf stoichiometry. Some stoichiometric variables were stable within the same slope aspect, whereas others varied under different slope aspects, suggesting that leaf stoichiometry was determined by both local-scale differences between sites and species identity. The range of variation in leaf stoichiometry showed a decreasing trend from individual species, to family, to community, indicating that a community's leaf stoichiometry cannot be derived from that of individual species or families. This suggests that research on plant response to environmental changes should focus on both the community level and the exclusive stoichiometry patterns of plants in this region.