喀斯特区天然林不同演替阶段功能性状特征及其影响因素研究——以云南大黑山为例

A Study of Functional Traits of Natural Secondary Forests and Their Influencing Factors in Different Succession Stages in Karst Areas: A Case Study of Dahei Mountain, Yunnan Province

不同演替阶段群落的环境条件有所不同,变化的环境因子驱使群落水平上功能性状和物种适应环境的生态对策改变,然而次生演替过程中群落功能性状和物种生态对策随演替时间的变化规律尚不清楚。本文以云南大黑山喀斯特地区弃耕后处于不同恢复阶段的天然次生林(3年,6年,20年,40年)和老龄林为研究对象,结合不同群落演替阶段的物种特征和群落结构,分析不同演替阶段叶、枝功能性状的变化规律,以及功能性状与环境因子的关系。结果表明:(1)随着演替的进行,土壤养分(除磷外)和水分逐渐增加,土壤容重先下降后趋于稳定,土壤pH变化不明显;比叶面积逐渐下降,叶片干物质含量和潜在最大高度逐渐增大。叶和枝的氮含量呈先下降后上升的趋势,磷含量均下降,N:P总体呈上升趋势。(2)冗余分析表明,演替早期灌木林阶段主要分布在土壤容重高,水分和养分相对匮乏的环境中,植物往往采取高养分含量、高光合速率、短寿命的开放性策略;演替后期乔木林阶段主要分布在土壤水分和养分相对肥沃的环境中,耐阴树种逐渐占据主导地位,植物通常采取低养分含量、低光合速率、长寿命的保守性策略。其中,土壤含水量、全氮含量、容重和有机质是影响喀斯特植物演替过程中功能性状变化的关键环境因子。研究喀斯特植物功能性状与环境因素随演替的变化规律,以及功能性状如何响应环境变化,旨在为今后科学指导人工植物群落构建和防止植被退化提供依据。

The environmental conditions of the community are different at different succession stages.The changing environmental factors may drive the changes in plant functional traits at the community level and the ecological strategies of the species'adaptation.However,mechanism of these changes in secondary succession has been understudied so far.Based on natural secondary forests(3 years,6 years,20 years,and 40 years)at different recovery stages after abandoning farming and old growth forests in Dahei Mountain karst areas of Yunnan Province,this study combine the species characteristics and community structure of different community successional stages.We analyzed the changes in leaf and branch functional traits during the succession and the relationship between functional traits and environmental factors.The results are as follows:(1)As the succession progressed,soil nutrients(except phosphorus)and soil water content gradually increased,soil bulk density decreased first and then stabilized,meanwhile soil pH did not change significantly;specific leaf area gradually decreased,leaf dry matter content gradually increased,and the potential maximum height also gradually increased.The nitrogen content of leaves and branches decreased first followed by increase,the phosphorus content of leaves and branches decreased,and N:P generally increased during community recovery.(2)Redundant analysis shows that,in the early successional stage,plants were mainly distributed in soils with higher soil bulk density and lower water and nutrients content,and plant species often adopted open strategies with high nutrient content,high photosynthetic rate,and short life span.While in the late successional stage,plants was mainly distributed in more fertile soil with higher soil moisture and less sunlight,and shade-tolerant tree species gradually dominated the communities,and plant species usually adopted conservative strategies with low nutrient content,low photosynthetic rate,and long life span.Among all the environmental factors,soil water content,total nitrogen content,bulk density and organic matter seem to have been the key factors influencing the change of functional traits during the succession of karst plant communities.The study of the trend of functional traits of plant species and environmental factors during community succession and the problem as to how functional traits respond to environmental changes could provide references for guiding construction of artificial plant communities and preventing vegetation degradation in karst areas in the future.