Community level response of leaf stoichiometry to slope aspect in a montane environment: A case study from the Central Qilian Mountains, China

Leaf stoichiometry, a key indicator of plant response to environmental changes, can be significantly altered by changes to the environment caused by natural or artificial factors. Slope aspect, an important topographic factor, influences a plant’s exposure to solar radiation, precipitation, and other environmental factors, thereby affecting leaf stoichiometry. Under four slope aspects (south-facing, SF; south-west-facing, SW; north-west-facing, NW; north-facing, NF) at each of three sites in northwest China’s Qilian Mountain range, several soil properties and the dominant plant species’ concentration of leaf carbon (Cleaf), leaf nitrogen (Nleaf), and leaf phosphorus (Pleaf)] were measured. The highest Cleaf, Nleaf and Pleaf (522.03 mg g−1, 25.32 mg g−1, and 2.33 mg g−1, respectively) occurred under SW, SF and NF slope aspects, respectively, and the lowest values of leaf C:N (21.28), C:P (253.60), and N:P (11.18) were recorded under SF, NF, and NF slope aspects, respectively. Overall, on the SF, SW, and NW slope aspects, the limiting nutrients were N and P, but on the NF slope aspect only N was limiting. Besides highlighting the dependency of leaf stoichiometry on slope aspect, the present study showed that plant communities in montane ecosystems adapt to different combinations of water and heat through both elemental plasticity and changes in species composition. Therefore, leaf stoichiometry may show greater variability in high-altitude areas that are more sensitive to global change, and should be dynamically monitored to help managers develop sustainable vegetation management practices in these regions