Nitrogen (N) and phosphorus (P) resorption of two dominant alpine perennial grass species in response to contrasting N and P availability

Abstract

Nutrient additions may affect plant nutrient resorption and hence alter plant community composition and nutrient cycling in ecosystems. However, there is still much debate about how changes in nutrient availability affects nutrient resorption. Field experiments were conducted in 2013 on the Kunlun Mountain alpine grassland in northwestern China to investigate the variation between two dominant grasses Stipa capillata and Seriphidium rhodanthum in term of their nutrient resorption response to contrasting N and P addition levels. Results showed increasing N addition reduced N resorption efficiency and proficiency, and the N:P resorption ratio for both grass species, but increased P resorption efficiency and proficiency for only S. rhodanthum. Phosphorus addition increased P and N resorption efficiency of S. rhodanthum. In contrast, P addition decreased P resorption efficiency but had no impact on N resorption efficiency of S. capillata. Our results suggest that nutrient resorption responses to nutrient availability differed between perennial grass species. For both species, P additions reduced P resorption proficiency but increased N resorption proficiency. Thus, nutrient resorption is sensitive to soil nutrient availability and is an important strategy for nutrient conservation strategy for alpine grasses.