浙东常绿阔叶林植物功能性状对土壤含水量变化的响应

Responses of soil water content to change in plant functional traits in evergreen broadleaved forests in eastern Zhejiang Province

研究群落演替过程中植物功能性状与土壤含水量的关系,揭示植物对水分供给变化的响应策略,具有重要的生态学意义。该研究以浙江东部天童山、南山和双峰山的3个常绿阔叶林演替系列为对象,旨在探索不同演替阶段常见植物的功能性状与森林群落土壤含水量的相互关系。研究结果显示:森林演替中后期的树木高度、树冠面积、叶片干物质含量显著大于演替前期植物;相反,叶片净光合速率和蒸腾速率随演替进程而降低。随森林演替,表层土壤(0–20 cm)的含水量显著增加,深层土壤(20–40 cm)含水量随演替进程增加但不显著。表层土壤含水量与树木高度、树冠面积和叶片干物质含量显著正相关,与叶片净光合速率和蒸腾速率显著负相关;深层土壤含水量与树冠面积显著正相关,与叶片净光合速率、气孔导度和蒸腾速率显著负相关。树木高度、树冠面积、叶片干物质含量、叶片净光合速率、气孔导度和蒸腾速率均可解释土壤含水量随演替进程的变化趋势,而冠长比对土壤水分变化的响应最为敏感。

Aims Study on the relationships between plant functional traits and soil water content is important for revealing potential impact of vegetation dynamics on soil water dynamics. The objective of this study was to understand the change of soil water content （Ws） through forest succession. MethodsThe study sites are located in Tiantong, Nanshan and Shuangfeng Mountains in eastern Zhejiang Province. We measured 10 functional traits for common plant species andWsin forest plotsrepresentative of three successional stages of evergreen broadleaved forests. The Pearson correlation and the stepwise regression were conducted to determine the quantitative relationships between plant functional traits andWs. Important findings Tree height （H）, crown area （CA） and leaf dry matter content （LDMC） were significantly higher for species at intermediate-and late-successional stages than for species at early-successional stage. In con-trast, max net photosynthetic rate （Pmax） and transpiration rate （Tr） of dominant species declined with forest suc-cession. TheWs in the surface soil layer （0–20 cm） increased significantly, whereasWs in the subsurface soil layer （20–40 cm） did not significantly change through forest succession. With respect to the surface soil layer,Ws was positively correlated with each ofH, CA andLDMC, but negatively correlated with each ofPmax andTr. With re-spect to the subsurface soil layer,Ws positively correlated withCAonly, and negatively correlated with each of Pmax, stomatal conductance （Cond） andTr. Variation in soil water content with forest succession could be ex-plained mostly byH, CA, LDMC, Pmax,Cond andTr, and the ratio of crown depth to tree height （CD/TH） was mostly sensitive to the change of soil water content during forest succession.