Dynamic life table and response to temperature change of Salicornia europaea in Ayding Lake

Ayding Lake, located in the extreme arid region in Middle Asia, has a unique environment condition. Occluded terrain leads to high temperatures in summer. Currently, no studies have shown how this area is affected by Salicornia europaea. In this study, 3 sample plots with different water and population characteristics were selected and named plots A, B, and C. Plot A was a high terrain, with no water on the surface after April and low plant density. The surface of plot B was covered with water for a long period, and it had moderate plant density. The surface of plot C was covered with water during the early months of the year, and it had the highest plant density. We set 3 quadrats of 0.5 m×0.5 m in each plot. Each quadrat was investigated 1~2 times a month, and the plant density was counted 10 times. By using dynamic life table and correlation analysis, we studied the relationship between population change and temperature. The results showed that S. europaea populations grew before May. In all plots, the high mortality period for S. europaea populations was from May to June because of self-thinning triggered by increase in temperature and reductions in moisture and nutrients. The S. europaea populations of plots A and B showed a second high mortality period from July to August because of the extreme temperature of 43 ℃ for 43 days. The S. europaea population in plot A showed a third high mortality period in September because of high temperature and salt stresses caused by evaporation of soil moisture resulting in increased salt concentration. The plant mortality noted in plots A and B was significantly correlated with temperature. S. europaea population in plot C had only one period of high mortality, but this was not significantly correlated with temperature. This is because compared to plots A and B, plot C had more moisture and higher plant population density, which can relieve the stress of high temperature. The survival curves of plant populations in plots A and B belong to Deevey type Ⅲ, which show high mortality rates at the beginning of the year, but tend to become steady with time. The survival curve of plant population in plot C belongs to Deevey type Ⅱ, which shows the same mortality rate at all times in a year.