Abstract: In order to analyze the response of wetland plant phenotypic plasticity and biomass to soil moistures,this study selected Carex moorcroftii as the research object,and sampling plots were set along a soil moisture gradient to analyze the changes of root,stem,leaf morphology and biomass. The results showed:Leaf number,residual leaf bases number,stem diameter,rhizome length and tiller buds number all increased with the decrease of soil moisture,while leaf length,tiller buds diameter and rhizome diameter decreased. Root surface area,root mean diameter,total root volume,belowground biomass,aboveground biomass and BB/AB ratio all decreased with aggravation of drought,while total root length increased. On the whole,the plasticity strength of vegetative organ was:root > stem > leaf. In the process of habitat aridity,the leaf length of C. moorcroftii was shortened,but leaf number was increased. So,the leaf area was maintained while the transport distance was shortened. In the meantime tiller buds number and rhizome length of C.moorcroftii were increased to enhance the ability of occupied space,it also increased root length for absorbing the deep soil water. The morphological characteristics of root,stem and leaf had certain plasticity,but the decrease of biomass limited the distribution of C. moorcroftii in arid habitats.

Key words: Carex moorcroftii, Moisture gradient, Morphological characteristics, Swamp wetland, Phenotypic plasticity

摘要： 为分析湿地植物形态与生物量可塑性对土壤含水率的响应，本文以青藏苔草(Carex moorcroftii)为研究对象，沿土壤水分梯度设置样地，分析根、茎、叶形态及生物量的变化。结果表明：随土壤含水率降低，叶片数量、残存叶基数量、茎基直径、根状茎长度和分蘖芽数量均增加，而叶长、分蘖芽和根状茎直径减小；根系表面积、根系平均直径、总根体积、地下(BB)、地上(AB)生物量、BB/AB值均随土壤含水率降低呈减小趋势，而总根长呈增大趋势；营养器官形态特征可塑性强弱表现为：根>茎>叶。在生境干旱化过程中，青藏苔草叶片长度缩短、数量增多，在缩短输导距离的同时保持植株的叶面积，同时青藏苔草会增加分蘖芽数量与根状茎长度以增强对空间的占据能力，增加根长以吸收利用深层土壤水分，根、茎、叶形态特征具有一定的可塑性，但生物量的降低限制了青藏苔草在干旱生境中的分布。

关键词: 青藏苔草, 水分梯度, 形态特征, 沼泽湿地, 表型可塑性