演替和气候对阔叶红松林土壤有机碳密度的影响

东北阔叶红松林及其次生林是我国重要的森林碳库,土壤中储存着大量的有机碳。本研究调查了纬度梯度上的4个典型地点(长白山、蛟河、五营和胜山)不同演替阶段(杨桦林、硬阔叶林、红松近熟林和成熟林)的土壤有机碳密度(SOCD),并分析了总SOCD(0~60 cm)、表土层SOCD(0~20 cm)与演替、气候等因素的关系。结果表明:各研究地点的总SOCD、表土层SOCD和表土层占总SOCD的比例随演替的进展并没有一致的变化趋势。总SOCD与纬度、最冷月均温、年降水量和温暖指数无显著关系;表土层SOCD、表土层/总SOCD比例随纬度增加而显著降低,随最冷月均温升高而显著上升。多元分析表明,气候因子本身对表土层SOCD的解释力高于对总SOCD的解释力,演替阶段对3个SOCD变量的解释力均不显著,但演替阶段与温度指标(最冷月均温或温暖指数)的交互作用对总SOCD和表土层/总SOCD比例影响显著。此外,坡位对总SOCD和表层SOCD都有显著影响。研究表明,表土层SOCD可能主要受气候梯度和小地形影响;总SOCD的异质性较强、影响因素复杂,气候因子自身对总SOCD的影响较弱,群落特征(生活型、蓄积量)和小地形、以及演替与气候的交互作用对总SOCD的影响显著。 

The influence of succession stages and climate on soil organic carbon density of broad-leaved Korean ;pine forest

Broad-leaved Korean pine ( Pinus koraiensis ) forest and its secondary forests are important forest carbon sinks in northeast China and store a large amount of organic carbon in the soil. In this study we measured soil organic carbon density ( SOCD) for different succession stages of Broad-leaved Korean pine forest at four typical sites ( Changbai Mountain, Jiaohe, Wuying and Shengshan ) . We analysed total SOCD (0--60 cm) , SOCD at the depth of 0--20 cm ( topsoil) and the ratio of topsoil to total SOCD ( top/total ratio) in relation to abiotic and biotic factors. The results showed that total and topsoil SOCD, and top/total ratio, changed differently with forest succession in different sites. Total SOCD was not related to latitude and three key climatic indices: mean temperature of the coldest month ( MTCM ) , annual precipitation ( AP) , and warmth index ( WI ) , while topsoil SOCD and top/total ratio were negatively related to latitude and positively related to MTCM. Multivariate analyses showed that total SOCD was less affected by climate than topsoil SOCD. Succession stage itself was not significant in explaining the SOCD variables, but the interaction of succession stage with temperature indices ( MTCM and WI ) showed a significant role for total SOCD and top/total SOCD ratio. In addition, total and topsoil SOCD were also significantly affected by slope position. Our results showed that topsoil SOCD was affected by climate and local topography. Total SOCD, however, is affected by a number of factors together. In addition to the weak direct effect of climate, community structure ( lifeform and stand volume) , local topography and the interaction of climate with succession stage also showed a significant effect on total SOCD.