三峡库区消落带主要草本植物功能性状特征

摘要

三峡库区消落带环境的异质性主要体现在不同高程生境经受水淹的时间和深度不同.本研究选取消落带3个典型样地,通过分析37种主要草本植物各器官的功能性状,比较不同生活型和不同科别植物功能性状的差异;通过探讨消落带植物功能性状、性状间权衡关系对不同高程(对应不同的淹水环境)的响应,获取不同高程生境的植物生长及资源利用的适应策略.结果表明,1)不同生活型的植物功能性状中,多年生植物的叶干物质含量(LDMC)和细根组织密度(FRTD)显著高于一、二年生植物(P〈0.05),不同科别的植物功能性状中,除比叶面积(SLA)外,其余指标均存在显著差异(P〈0.05);2)随着高程降低,植物的平均SLA和比根长(SRL)先减小后增加,株高(H)和茎干物质含量(SD-MC)、LDMC表现出降低的趋势;3)综合考虑各高程的所有物种,SDMC与H、LDMC及FRTD显著正相关(P〈0.05),SRL和细根的比根表面积(SRA)均与H、SDMC、FRTD显著负相关(P〈0.05);4)不同高程的植物功能性状间关联表现出趋同性,尤其在中间的两个高程吻合度较大.以上结果说明:消落带草本植物形成不同的性状组合适应环境;在淹水时间较长的低高程生境中,植物表现出"低投入-快速回收"的生长策略,而较高高程生境中的植物则对组织构建有较大的投入;不同生境的植物功能性状间关联的趋同性,体现了消落带草本物种间已表现出趋同适应的特点.%The environmental heterogeneity of the hydro-fluctuation belt in the Three Gorges Reservoir is illus-trated by the fact that each elevation corresponds to a different time and depth of water submergence.We ana-lyzed seven plant functional traits in 37 major herbaceous species from three sample sites in the reservoir hydro-fluctuation belt.We then divided the plant species into different groups (including different life forms and dif-ferent plant families)and analyzed variations in their functional traits.To determine growth and resource utili-zation adaptability of plants located in different elevation belts,we analyzed the plant functional traits and trait correlations at different elevations (corresponding to different water environments).We identified four particu-lar traits in the results.1)Leaf dry matter content (LDMC)and fine root tissue density (FRTD)of perennials were significantly higher than those of annuals and biennials (P〈0.05).In addition to specific leaf area (SLA), significant trait differences were found among different plant families (P〈0.05).2)With a reduction in eleva-tion,the average SLA and specific root length (SRL)of plants first decreased and then increased,while plant height (H)and dry matter content of leaves and stems showed a trend to decline.3)Taking all plant species in-to account,there were significant positive correlations between stem dry matter content (SDMC),H,LDMC, and FRTD (P〈0.05).By contrast,SRL and specific root area (SRA),both fine root traits,were negatively related to H,SDMC,and FRTD (P〈0.05).4)There was convergence in plant traits among different elevation belts.The study showed that different herbaceous plant groups generate various trait combinations to adapt to the environment.Plants growing in lower elevation habitats have a low investment and quick recovery growth strategy,and vice versa.The plant trait correlation convergence among different elevation habitats implies a convergent adaptation of herbaceous plants in the hydro-fluctuation belts of the Three Gorges Reservoir.