科研之友
微信
新浪微博
Facebook
分享链接
摘要
Nutrient resorption from senescing leaves is a key nutrient conservation strategy in many ecosystems. In evergreen broad-leaved forests, nutrient resorption occurs with concomitant defoliation almost year-round. However, it is unclear whether nutrient resorption efficiency (NuRE) varies in different defoliation seasons for evergreen broad-leaved trees and how it may relate to soil nutrient availability. Castanopsis eyrei is a dominant tree species in evergreen broad-leaved forests in southern China, with distinct bimodal patterns of defoliation in spring and autumn. We investigated seasonal variation of the resorption efficiency of nitrogen (N) and phosphorus (P) of C. eyrei leaf and its relationship with soil mineral N by measuring the concentrations in leaf, leaf litter, and soil for two consecutive years. We hypothesized that leaf NuRE should be higher in seasons with low soil nutrient availability. We found that on average, soil mineral N content was 38.5 % lower during the autumn defoliation peak than in spring, and N and P concentrations in leaf litter at the spring defoliation peak were 10.0 and 26.7 % higher than at the autumn peak. Nitrogen NuRE at the autumnal defoliation peak was 5.1 % higher than that at the spring peak (49.3 vs 44.2 %), and the phosphorus NuRE in autumn was 6.8 % higher than that in spring (77.6 vs 69.8 %). Our findings suggest an inverse relationship between soil nutrient availability and NuRE and that the dynamics in NuRE should be incorporated into modeling of biogeochemical cycling in evergreen forest ecosystems with a bimodal defoliation pattern.
