Soil nutrients and climate seasonality drive differentiation of ecological strategies of species in forests across four climatic zones

Aim Ecological strategies are the growth and survival tactics employed by species in response to various environmental conditions. We aimed to identify the abiotic drivers for variation in ecological strategies of species in forest vegetation across different climatic zones. Methods We established 50 0.04-ha forest dynamics plots in each of four forest vegetation types across different climatic zones respectively. Three leaf functional traits (leaf area, specific leaf area and leaf dry matter content) of woody plant species and 7 soil factors were sampled and measured. Based on competitor, stress-tolerator, ruderal (CSR) theory and the CSR ordination method (StrateFy), we classified plants into four groups according to their ecological strategies. Redundancy analysis was used to access the key drivers of variation in plant ecological strategies across different forest types. Results The proportion of C-strategists decreased with increasing latitude, from tropical to cold-temperate forests. Except for the tropical forest, the proportion of S-strategists increased while that of Int-strategists (the intermediate type of strategy between the competitor, stress-tolerator, and ruderal strategies) decreased with increasing latitude. Ten abiotic variables (soil pH, available phosphorus, available nitrogen, precipitation of the warmest quarter, temperature seasonality, annual temperature range, precipitation of the wettest month, mean temperature of the warmest quarter, elevation, and precipitation of the driest month) were significantly correlated with plant ecological strategies of species in different forest types. Conclusions Contrary to our expectation, soil nutrients were more important than seasonal climatic factors in determining the ecological strategies of species in forests across different climatic zones.