三峡库区不同生境下中华蚊母树叶片表型可塑性及其与土壤环境因子的关系

摘要

探究中华蚊母树在不同生境水文节律下的生态适应性——表型可塑性,以及它的土壤环境影响因子,对其在异质生境下的生存适应策略具有重要的生态学意义.调查中华蚊母树在自然消落带、反季节消落带及无消涨节律生长区等3种异质生境下36个不同种群叶片主要结构性状叶长(LL)、叶宽(LW)、叶面积(LA)、叶干物重(LDW)以及比叶面积(SLA)的可塑性及其土壤环境影响因子.对各异质生境下中华蚊母树叶片性状的差异显著性进行分析,将LL、LW、LA、LDW之间的异速生长关系用经典异速方程来描述.运用典范对应分析(CCA)研究中华蚊母树叶片性状与土壤环境因子之间的关系.结果显示,中华蚊母树种群的LL、LW、LA、LDW及SLA等5个叶片功能性状在异质生境之间均有显著性差异(P＜0.05),变异系数平均值在4.80％-26.12％之间,其中LA和SLA在各生境中变异系数最大.各异质生境下中华蚊母树LW与LL、LDW与LL、LW及LA均呈显著的幂函数异速生长关系.其异速系数lgβ均表现极显著差异(P＜0.01),但其异速指数a却表现相同的规律:LW与LLa＜1,LDW与LL、LWa＞1,LDW与LAa≈1,即在不同生境下叶片各性状的生长速率均表现为:LA≈LDW＞LL＞LW.各异质生境中叶片较大的表型可塑性和一致的异速生长规律表明了中华蚊母树面对不同的水文节律具有较宽的生态幅,且表现出生长的一致性.CCA排序结果显示,全磷(TP)、水解氮(AN)、速效钾(AK)及土壤含水量(SWC)是中华蚊母树叶片表型可塑性的主要影响因素,中华蚊母树主要通过这些土壤环境因子的驱动改变叶片结构性状使其能在不同水文节律的异质生境中表现出最佳的适合度.%Phenotypic plasticity is of great ecological significance to the survival of plants in heterogeneous habitats.With phenotypic plasticity,plants can maximize access and effectively utilize resources in heterogeneous habitats.This study,based on large-scale analyses,discussed the phenotypic plasticity of Distylium chinense leaves and its soil environmental factors,which aimed to provide a basis for the protection of D.chinense and restoration of ecological environments in the riparian zone.The phenotypic plasticity of the main structural characters of leaves of 36 D.chinense communities and their relationship with soil environmental factors were investigated from 3 heterogeneous habitats (natural riparian,anti-seasonal water level fluctuation,and no water level fluctuation zones) in the Three Gorges Reservoir Region.Leaf traits,including leaf length (LL),leaf width (LW),leaf area (LA),leaf dry weight (LDW),and specific leaf area (SLA),were analyzed with significance analysis and their allometric relationships were determined.The relationships between leaf traits and soil environmental factors were evaluated by canonical correspondence analysis (CCA).The results showed that there were significant differences (P ＜ 0.05) in the five functional traits (LL,LW,LA,LDW and SLA) among heterogeneous habitats,and the mean of the coefficient of variance was 4.80％-26.12％.LW and LL,LDW and LL,LDW and LW,and LDW and LA showed significant allometric relations of power functions among heterogeneous habitats.Allometric coefficients (lgβ) among 36 communities showed highly significant differences (P ＜ 0.01),the allometric index (a) expressed the same regularity:LL and LW a ＜ 1,LDW and LL,LW a ＞ 1,LDW and LA a ≈ 1.Thus the growth rate of leaf traits was:LA ≈ LDW ＞ LL ＞ LW.The CCA results showed that total phosphorus (TP),total nitrogen (AN),available potassium (AK),and soil water content (SWC) were the main factors affecting D.chinense leaf phenotypic plasticity,which resulted in the adaptation of D.chinense to adverse flooding habitats.The leaf phenotypic plasticity and allometric growth pattern of D.chinense in heterogeneous habitats showed wide ecological amplitude under different hydrological regimes.In addition,the soil was lack of N and K in the Three Gorges Reservoir.The addition of N and K during vegetation restoration could balance soil nutrition,which could promote D.chinense growth.