Study On The Adaptive Strategies Of Clonal Plants In Heterogeneous Environments

Spacial and temporal heterogeneity is a ubiquitous feature of plant habitats, even in a tiny scale. In the evolutionary process, plants may have various adaptive strategies to environmental heterogeneity. Theoretically, clonal growth contributes markedly to the ability of clonal plants to make use of environmental heterogeneity. Generally, clonal plants possess stronger adaptability to environmental stress. Clonal plants were more abundant in high latitude and/or high altitude habitats with cold and dry whether poor nitrogens in the soil. The purpose of this thesis was. by using field investigation and container experiments, to study on the adaptive strategies of clonal plants to heterogeneous environments and the contribution of clonal integration and intraclonal division of labour to growth of clonal plants in different altitudes in the transitional zone between Qinghai-Tibet plateau and Sichuan basin.Two field investigations were conducted to study clonal architecture and ramet population characteristics of Lysimachia congestiflora growing in different light conditions and the variation of Fragaria vesca ramet population characteristics along the elevation gradient in the transitional zone between Qinghai-Tibet plateau and Sichuan basin. The results show that clonal architecture (stolon internode length, braching intensity, branching angle) and ramet population characteristics (density and biomass etc) of Lysimachia congestiflora were different in different light conditions. Ramet population density, ratio of root to shoot and ramet population spatial pattern of Fragaria vesca varied along the elevation gradient in the transitional zone between Qinghai-Tibet plateau and Sichuan basin. Based on resource acquisition strategy of clonal plants, these results are discussed in the context.Two field container experiments were conducted to study clonal integration of Duchesnea indica experiencing light heterogeneity at both high and low altitude and Fragaria vesca from different altitudes. The results show that clonal integration greatly enhanced the growth of stressed ramets. Cost-benefits analysis shows that the connected un-stressed ramets did not incur any cost, consequently the growth ofwhole clonal fragments was enormously enhanced. So. clonal integration may not only be adaptive for clonal plants to successfully inhabit its own habitats, but also ecologically important for clonal plants to grow in high -altitude habitats.Another two field container experiments were conducted to study intraclonal spatial division of labour in Fragaria vesca and Lysimachia christinae with different branching types and Lysimachia christinae at different altitudes in response to reciprocal patchiness of light and nutrients. The results show that the two studied clonal herbs demonstrated division of labour induced by reciprocal patchiness of light and nutrients. The environmentally induced division of labour may be helpful to clonal plants to acquire heterogeneous resources. So. spatial division of labor may contribute more greatly to ability for the clonal plants to exploit environmental heterogeneity. Its effect on performance of clonal plants at different altitudes may be different.