金沙江观音岩水库消落带绝对优势植物的表型可塑性与适应策略OACSTPCD

The Jinsha River is rich in cascade reservoirs in the upper reaches of the Yangtze River.The selection of typical reser-voirs in the Jinsha River area to carry out research on plant phenotypic plasticity and adaptation strategies has important reference value for the ecological management of reservoirs in this area.In this study,the riparian zone of Guanyinyan Reservoir in Jinsha River was taken as the study area.The phenotypic plasticity of root,stem and leaf traits of absolute dominant plants after years of periodic flooding disturbance was quantitatively compared,and the key traits of absolute dominant plants in response to dominant factors and their synergistic response characteristics and trade-off strategies were analyzed.The results showed that:1)A total of 21 plant species belonging to 21 genera and 11 families were recorded.Only Cynodon dactylon(C.dactylon)and Xanthium sibiricum(X.sibiricum)were the absolute dominant species with dominance greater than 0.1.2)Flooding had significant effect on the func-tional traits of C.dactylon and X.sibiricum.It was identified as the dominant factor contributing to the variation in functional traits of both species.3)The plasticity index of plant height,main stem length,branch number,main stem width,leaf number and leaf area of C.dactylon and branch number,leaf number,root shoot ratio and specific leaf area of X.sibiricum exceeded 0.6,which were sensitivity traits to cope with flooding.However,the leaf number,leaf area of C.dactylon and the specific leaf area of X.sibir-icum showed short-term timeliness in response to flooding,and they were non-adaptive plasticity.4)Flooding depth regulated the trade-off between the'escape'strategy and the'silence'strategy of C.dactylon,and responding synergistically through different trait combinations and the allocation of aboveground and underground resources.5)Flooding led to the convergence of ecological strategies of C.dactylon and X.sibiricum,and both adopted S/SR strategy.In addition,compared with C.dactylon,which is a commonly recommended species in the water-level-fluctuating zone of the reservoir,X.sibiricum has different opinions due to its risk of water pollution.However,X.sibiricum has important medicinal value,so mowing before each flooding is a consideration.