不同季节亚热带常绿阔叶林6个树种凋落叶钙、镁、锰的释放特征

Seasonal release characteristics of Ca,Mg and Mn of foliar litter of six tree species in subtropical evergreen broadleaved forest

采用凋落物分解袋法,研究了亚热带常绿阔叶林区马尾松、柳杉、杉木、香樟、红椿、麻栎6个典型树种凋落叶的Ca、Mg、Mn在第一个分解年不同雨热季节的释放特征.结果表明：经历1年的分解,6种凋落叶Ca、Mg、Mn释放率分别为-13.8%-92.3%、4.0%-64.8%和41.6%-81.1%.马尾松和香樟凋落叶Ca释放动态呈现富集-释放模式,其余4种凋落叶整体上呈现释放的模式;香樟凋落叶Mg释放动态呈现富集-释放模式,其余5种凋落叶呈现直接释放模式;柳杉和红椿凋落叶Mn释放动态呈现富集-释放模式,其余4种凋落叶呈现直接释放模式.凋落叶Ca、Mg、Mn的释放明显受到季节性降雨的影响,且因凋落叶种类不同而有差异.Ca、Mg、Mn在雨季的释放率和释放量均高于旱季.初始养分含量和降雨量是影响凋落物分解过程元素释放的重要因子.

Seasonal release dynamics of Ca,Mg and Mn during decomposition of foliar litter of Pinus massoniana,Cryptomeria fortunei,Cunninghamia lanceolata,Cinnamomum camphora,Toona ciliate,and Quercus acutissima were investigated in subtropical evergreen broad-leaved forest employing the method of litterbag. After one-year decomposition,the release rates of Ca,Mg and Mn in foliar litter of the studied tree species ranged from- 13. 8% to 92. 3%,from 4. 0% to 64. 8%,and from 41. 6% to 81. 1%,respectively. Ca dynamics in foliar litter of P. massoniana,C. camphora exhibited the pattern of accumulating early and releasing later,while that of the other four tree species showed direct release. Similarly,the dynamics of Mg released from foliar litter of C.camphora showed the pattern of accumulating early and then releasing,while that of the other five tree species exhibited continuous release. Meanwhile,the dynamics of Mn released from foliar litter of C. fortunei and T. ciliate exhibited early accumulation,and subsequent release,while that of the other four tree species showed continuous release. The releases of Ca,Mg and Mn in foliar litter were greatly influenced by seasonal rainfall,and varied with tree species. Furthermore,the rates and amounts of Ca,Mg and Mn released from foliar litter were higher in rainy season than in dry season. In conclusion,the initial nutrient concentrations and precipitation were two key factors influencing the release dynamics of Ca,Mg and Mn during decomposition of foliar litter in the subtropical evergreen broad-leaved forest.