大兴安岭森林演替过程中凋落物分解与DOC释放研究

Litter Decomposition and DOC Release During Forest Succession in Greater Khingan Mountains

基于"空间代替时间"法,在大兴安岭火烧后森林演替下的草丛、灌丛、白桦林、白桦落叶松林和落叶松林5个阶段样地的3个分层凋落物中,分别设置36、24、12℃3个温度梯度进行培养试验,测定凋落物析出的DOC浓度及剩余量,分析不同森林演替阶段不同凋落物层凋落物分解和释放DOC的动态。结果表明:凋落物分解速率和DOC释放量随演替序列均呈现先增大后减小趋势;随着温度升高,凋落物分解速率加快,DOC释放量增加;凋落物分解速率和DOC释放量呈现为未分解层大于酵层和腐殖质层。森林演替过程、温度、凋落物分层对于凋落物分解和DOC的释放有重要影响。

Three temperature gradients of 36, 24, and 12 ℃ were set for culture test in 3 layered litter of 5 stages of grass, shrub, Betula platyphylla forest, Betula platyphylla-Larix gmelinii forest and Larix gmelinii forest under forest succession after the fire in Greater Khingan Mountains based on the ’space instead of time’ method.The DOC concentration and residual amount of litter precipitation were measured, and the dynamics of litter decomposition and release of DOC in different litter layers in different forest succession stages were analyzed. Results show that the litter decomposition rate and DOC release increase first and then decrease with the succession sequence. As the temperature increases, the rate of litter decomposition increases and the amount of DOC released increases. Litter decomposition rate and DOC release amount appear as undecomposed layer larger than leaver layer and humus layer. Forest succession, temperature, and litter stratification have important effects on litter decomposition and DOC release.