Conclusion
Our 7-year field warming study demonstrated that warming led to a net transfer of soil P from moderately-available organic P and Fe-Pi to the plant without altering litter P mineralization and ecosystem P loss. Warming thus increases the plant biological “control” of the plant-soil P-cycle, increasing the stocks of P involved in the fast P plant-soil cycle and plant P-use efficiency (higher C:P ratio in litter). The results suggest that warming changed net balance of plant-P cycle through multiple processes (the enhanced plant P resorption, soil P mineralization and dissolution) rather than in single form or process, which extends our previous understanding of the climate-demand/supply hypothesis and the application of nutrient resorption theory and emphasizes the assessment of P dynamics at the ecosystem level. In this humid tropical forest under warming, greater P supply to support higher mass production is expected than previous prediction via short-term experiments or studies with single evaluation, and moderate warming may alleviate current P deficiency and/or limitation in tropical plants and contribute to greater plant C fixation in a warmer future climate.