The synergy of intrinsic ecological mechanisms of leaf nutrient resorption in temperate deciduous trees

Nutrient resorption is a critical process in plant nutrient conservation during leaf senescence. However, the underlying ecological mechanisms on the large variabilities in nitrogen (NRE) and phosphorous (PRE) resorption efficiencies remain poorly understood. We conducted a comprehensive study on NRE and PRE variability using 61 tree individuals of 10 temperate broadleaved tree species. Three potentially interrelated intrinsic ecological mechanisms (i.e., leaf pigments, energy residual and leaf senescence phenology) were verified. We found that delayed leaf senescence date, increased degradation of chlorophyll and carotenoids, biosynthesis of anthocyanins, and reduced nonstructural carbohydrates (particular sugars) coordinately and positively related with NRE and PRE. The intrinsic factors affecting the resorption efficiency were ranked in a decreasing order: leaf pigments > energy residual > senescence phenology. Our findings underscore the synergistic effect of the three ecological mechanisms on leaf nutrient resorption, and hold significant implications for comprehending how nutrient resorption responds to climate change.