秦岭主要森林凋落物中易分解和难分解植物残体含量及比值研究

Contents and Ratios of the Decomposable and Resistant Plant Material in the Litters of the Main Trees in Qingling Mountains

森林凋落物是森林生态系统中物质循环和能量流动的基础物质,凋落物中易分解植物残体(DPM)和难分解植物残体(RPM)含量及比值是反映凋落物分解速率的重要指标之一,英国洛桑试验站建立的土壤碳模型(Roth C)把DPM/RPM值作为一个重要输入参数模拟土壤有机碳的动态变化。已有的研究结果表明DPM/RPM的值与森林类型等有关,为了探明秦岭主要森林凋落物的DPM、RPM含量及其比值,采用硫酸水解法对秦岭主要森林凋落物的DPM/RPM值进行初步研究。结果表明:1)秦岭主要森林凋落物DPM/RPM的比值范围为0.45～1.22,其中白桦(Betulaplatyphylla)林的比值最高(1.22),华北落叶松(Larix principisi)林的最低(0.45),其平均值为0.792;不同森林类型排列顺序为白桦林>锐齿栎(Quercus aliena var.acuteserrata)林>油松(Pinus tabulaeformis)林>巴山冷杉(Abies fargesii)林>华北落叶松林;2)不同类型森林凋落物中易分解植物残体DPM所占比例在31%～55%之间,其中阔叶林的DPM值平均为49.3%,大于针叶林的35.3%,从一个侧面证明阔叶林凋落物更容易被土壤微生物分解利用,针叶林凋落物有机碳周转的时间要长于阔叶树植物。这一结果将为今后利用Roth C模型进行秦岭林区不同森林生态系统土壤有机碳动态模拟提供参考。

Forest litter is the basic substance of the material circulation and the energy flow in the forest eco- system. The contents and the ratios of the decomposable plant material （DPM） and the resistant plant ma- terial （RPM） are important indices to reflect litter decomposition, In the Roth C model, values of DPM and RPM act as important aspects to simulate dynamic changes of soil organic carbon. The research results reported demonstrated that the DPM/RPM values were closely related to the forest types. The content and the ratio of DPM and RPM of the main forest litters in the Qingling Mountains were examined by the method of sulfuric acid hydrolysis. The results showed that the ranges of the ratio of DPM to RPM in the Qinling Mountains were between 0.45 to 1.22. The values of DPM/RPM among different forests were in the order of 13etula platyphylla 〉 Quercus aliena var. acuteserrata 〉 Abies fargesii 〉 Pinus tabulae- forrnis 〉 Larix principis）. The DPM average ratio of the broad leaved trees were 49.3 %, higher than that of coniferous tree （35.3%）, indicating that the rate of decomposition of coniferous trees were lower than broad-leaved trees. It also proved that it took more time on the turnover of soil carbon in the conifers plants＇ soil than in the broad-leaved trees＇ soil. The results will provide references for the future use of Roth C model to simulate the dynamic changes of the soil organic carbon in different forest systems in the Qingling Mountains.