关键词: 养分重吸收, 氮, 养分利用策略, 生活型, 亚热带森林

Abstract: Aims The reabsorption of nitrogen (N) by leaves before senescence can reduce the dependence of root uptake after N release from decomposing litter. However, weather N reabsorption efficiency is dependent on the N contents in fresh leaves and in soils remains poorly understood, and weather this coupling varies with life forms is also largely unknown. Methods Here we collected fresh and senescent leaves of 92 woody plants in subtropical forests in southern China and complied a global dataset of N reabsorption efficiencies from 54 literatures to evaluate the coupling of N reabsorption efficiency with N contents in fresh leaves and in soils across various life forms. Important findings We found that: 1) In subtropical forests and on global scale, there was no significant difference in leaf N reabsorption efficiency between evergreen and deciduous and between angiosperms and gymnosperms species. On the global scale, the leaf N reabsorption efficiency of trees was significantly greater than that of shrubs, and the efficiency of ectomycorrhizal woody plants was significantly higher than that of arbuscular mycorrhizal woody plants. 2) The N reabsorption efficiency of evergreen woody plants was significantly correlated with the initial N content in fresh leaves, while this coupling was not found for angiosperms versus gymnosperms or ectomycorrhizal versus arbuscular mycorrhizal woody plants. 3) The N reabsorption efficiencies of evergreen, angiosperms and ectomycorrhizal woody plants were significantly correlated with soil N content at the sampling sites, while those of deciduous, gymnosperms and arbuscular mycorrhizal woody plants were not significantly correlated with the soil N content. Our results suggest that there are differences in N reabsorption efficiency among woody plants with different life forms. These differences are primarily influenced by nutrient acquisition strategies, which is of great significance for revealing the differentiated nutrient utilization strategies among plants.

Key words: nutrient reabsorption, nitrogen, nutrient utilization strategy, life forms, subtropical forest