Optimizing foliar allocation of limiting nutrients and fast‐slow economic strategies drive forest succession along a glacier retreating chronosequence in the eastern Tibetan Plateau

Abstract

Nitrogen (N) and phosphorus (P) availabilities limit plant productivity, especially in primary succession; however, our understanding of species-specific strategies regarding their allocation and coordination with other functional traits remains limited. Community-weighted mean traits were compared to decipher the ecophysiological mechanisms of forest succession in nine dominant species along 120-y successional stages across a glacier-retreating chronosequence. High foliar N and P concentrations in N2-fixing plants on a 12-year-old surface did not result in high photosynthetic capacity due to the inefficient allocation, as indicated by their low photosynthetic N- and P-use efficiencies. On a 40-year-old surface, exploitative strategies, manifested in a higher specific leaf area and greater N allocation to Rubisco, as well as quick-return energy economics, helped deciduous forests dominate. When P availability decreased on a 120-year-old surface, evergreens maintained high photosynthetic P-use efficiency, by reducing overall P concentration and its allocation to structural fraction. Efficient P allocation and a higher ratio of leaf lifespan to payback time facilitated the dominance of evergreens in low P-sites. Optimizing allocation of limiting N or P among foliar fractions and fast–slow economic strategies drive primary succession after glacier retreat. Integrating the above- and below-ground subsystems through food webs will provide further insights into ecosystem dynamics.