百山祖常绿阔叶林凋落量的季节变化及其驱动因素

Dynamics of Litterfall and Its Influential Factors in Evergreen Broad-leaved Forest in Baishanzu Mountain

单位时间和单位面积上的森林凋落物产量(凋落强度)的季节动态受多方面因素的影响。为了解百山祖常绿阔叶林营养器官(含叶、小枝、树皮及它们的碎片)凋落强度的季节动态及其影响因素,2009—2016年,在逐月统计百山祖森林固定样地内50个收集器收集的树木营养器官凋落物及各组分的凋落强度的基础上,利用多元逐步回归分析研究月平均气温和单月总降水量年际波动与营养器官凋落物及各组分月凋落强度年际波动的关系。结果表明,百山祖常绿阔叶林营养器官年均凋落强度为362.91 g·m^(-2)·a^(-1),叶凋落物的占比最大,达87.33%,其中常绿树种叶凋落物占67.07%,落叶树种叶凋落物占19.69%,针叶树针叶凋落物仅占0.56%;营养器官凋落物及各组分的凋落强度存在明显的季节动态,凋落高峰多在4—5月和10月出现,常绿树种主要在5月前后形成树叶凋落高峰,且在10月左右形成树叶凋落小高峰,落叶树种主要在10月左右出现叶凋落高峰。逐步回归分析的结果表明,去平均单月总降水量(即某月总降水量减去该月总降水量的8年均值)显著提高营养器官凋落物尤其是常绿树种叶凋落物的去平均月凋落强度(即某月凋落强度减去该月凋落强度的8年均值),而月平均气温年际波动对营养器官凋落物及其组分的月凋落强度年际波动无显著影响。降水可能通过形成较强冲击力损毁植物枝叶从而提高营养器官凋落物的凋落强度。

During 2009 to 2016,vegetative organs(including leaf,branch,bark and their debris)were collected by 50 litter collectors from a permanent sample plot in evergreen broad-leaved forest in Baishanzu Mountain,Zhejiang province.Multiple stepwise regression analysis was used to study the relationship between change of monthly mean temperature and single monthly precipitation with litterfall of vegetative organs and of their components.The results showed that the average annual litterfall of vegetative organs was 362.91 g/m^(2),dominated by the leaf litterfall,accounting for 87.33%,among them,the leaf litter of evergreen species accounted for 67.07%,that of deciduous species 19.69%,and that of coniferous species 0.56%.The dynamics of litterfall of vegetative organs and its components were obvious with the peaks of litterfall in April-May and October.The results of stepwise regression analysis showed that the de-average monthly total precipitation 2009-2016 significantly increased the de-average monthly litterfall of vegetative organs,especially of evergreen tree species,while annual change of monthly average temperature had no significant effect on annual variation of monthly litterfall of vegetative organs and the components.