浙江天童国家森林公园常绿阔叶林凋落叶养分含量的时空分布特征

植物凋落叶养分含量的时空分布格局在森林生态系统的物质循环和能量流动中发挥着关键作用，尤其是对森林土壤养分情况有重要的影响，而在群落结构复杂的亚热带森林中基于群落整体水平的凋落叶养分含量特征研究相对匮乏。在位于浙江天童国家森林公园中的20 hm²动态监测样地进行，收集凋落叶并测定其碳、氮、磷含量，结合不同生活型物种的凋落高峰，春季和初夏为常绿树种凋落高峰；秋季为落叶树种凋落高峰，以及地形特征对凋落叶养分含量的时空分布特征进行探究。结果表明：在时间尺度上，凋落叶养分含量表现为不同凋落高峰之间的差异，碳含量表现为秋季高峰 < 春季高峰 < 初夏季高峰，氮、磷含量为秋季高峰大于春季和初夏季高峰；在空间尺度上，凋落叶养分含量则表现为沟谷地形和山脊地形之间的差异性，在秋季凋落高峰时碳含量在沟谷地形显著低于山脊地形，氮、磷含量在山脊地形显著低于其他地形。研究结果表明群落物种组成及其生活型差异是造成森林群落水平凋落叶养分含量时空差异的主要原因。

Spatiotemporal distribution characteristics of leaf-litter nutrients in a dynamic plot of subtropical evergreen broad-leaved forest in Tiantong, Zhejiang Province

Litterfall, which is the basic carrier of nutrients, is a major contributor to material recycling and energy transformation in a forest ecosystem. However, only a few studies focus on the spatiotemporal distribution characteristics of leaf-litter nutrients in a subtropical forest community with high diversity. Therefore, in this study, we estimated the composition of leaf-litter nutrients, including total carbon, nitrogen, and phosphorus contents, by collecting the leaf-litter during the year from evergreen species in spring and summer litter peak and from deciduous species in autumn litter peak; we utilized a 20 hm² dynamic plot of subtropical evergreen broad-leaved forest in Tiantong with tough topography. Our results indicated that, in the temporal scale, the C concentration in the leaf-litter was lower in the autumn peak litter of deciduous species than that in the spring and summer peak litter of evergreen species, while the N and P concentrations were higher in autumn peak of deciduous species than that in the spring and summer peak litter of evergreen species. Further, in the spatial scale, the C concentration in the leaf-litter was lower in the valley than that in the ridge, while the N and P concentrations were lowest in the ridge among habitats in the autumn peak litter of deciduous species. These results indicated that the species composition and lifeform of communities determine the spatiotemporal distribution of the leaf-litter nutrients in a subtropical evergreen broad-leaved forest.