Abstract: Nutrient resorption (NuR) is the key strategy for plant adaptation to environmental stresses and optimization of nutrient use and is crucial for maintaining plant nutrient economy and ecological functions. This paper focuses on nitrogen (N) and phosphorus (P) in leaves, reveals the mobilization and transfer pathways of nutrient elements, summarizes the general rules of nutrient resorption efficiency (NuRE) in different elements, tissues/organs, growth stages, functional groups, and ecosystems, reviews the regulatory mechanisms of genetic traits (e.g., structural tissue, leaf longevity, etc.) and environmental factors (e.g., climate and climatic changes, soil nutrients, N and P deposition, etc.) on NuR and their impacts on ecosystems, and outlines the directions for future research. It was found that N mobilization was mainly depended on proteolysis, whereas P involved the degradation of nucleic acids, phospholipids and the release of vesicular inorganic phosphorus (Pi). The NuRE of high-mobility and high-demand elements (e.g., N, P, potassium) was significantly higher than that of low-mobility and low-demand elements (e.g., calcium, iron, and aluminum). Leaves, as highly metabolically active organs, showed a higher NuRE than organs such as roots and stems. The NuRE followed a single peaked curve with growth stage, peaking at maturity. Herbaceous and deciduous plants had higher NuRE than that of woody and evergreen plants due to less structural tissue. The NuRE of tundra, desert, and wetland ecosystems was generally higher than that of forest and grassland, and was characterized by a clear variation in different climatic zones. Genetic traits determine the physiological threshold of NuR by limiting the mobilization efficiency of nutrient, whereas environmental factors drove the dynamics of NuR, and its efficiency was significantly enhanced in infertile or arid environments. NuR was coordinated with below-ground nutrient acquisition strategies, and they are regulated by soil fertility and climatic gradients. The interspecific variability and plasticity of NuR played important roles in regulating nutrient cycling, building plant communities, and enhancing ecosystem stability. Future research should combine molecular biology with long-term field experiments to investigate the adaptive mechanisms of NuR to multiple environmental stresses and the feedback effects of its changes on the ecosystem, thereby providing a scientific basis for coping with global change and optimizing ecosystem management.

Key words: Nutrient resorption, nitrogen and phosphorus, nutrient mobilization, spatial-temporal pattern, global change