Response of vascular structure of a lakeside dominant plant species Hippuris vulgaris L. to simulated warming in Napahai wetland of Northwestern Yunnan
Vascular structure is the main transport structure of plants,which plays an irreplaceable role in the processes of plant photo-accumulation,growth and development,adaption to changes, reproduction and dispersal. Temperature is an important environmental factor affecting vascular structure. How temperature affects the vascular structure of wetland plants,however,is not well understood. In this study,we studied the responses of vascular structure of a lakeside dominant plant species Hippuris vulgaris L. to simulated warming,by using open-top growth chambers (OTCs) in Napahai basin. Napahai basin is a typical plateau wetland in Northwestern Yunnan and belonged to the temperature-sensitive area. The results showed that warming had greater effects on the vascular structure of the aboveground stem,but had less influence on that of the underground stem. For the aboveground stem,warming significantly promoted the number and size of catheters and screens,and the size of vascular bundle,but with minor effects on the density of catheters and screens. In contrast,warming significantly reduced the size of conduits and screens in underground stem,but both traits didn't show significant differences between the two warming treatments. Warming had no effects on other traits of vascular structure in underground stem. The mean annual temperature (MAT) and mean daily temperature (MDT) were the main factors affecting vascular traits,both of which had positive correlations with all the vascular traits. Our results indicated that climate warming obviously affected the transmission capacity of vascular structures of lakeside dominant plants in the plateau wetland of Northwestern Yunnan,which may lead to changes in physiological functions of plants and thus facilitate plant adaption to the warming environment.