艾丁湖盐角草种群动态生命表及其对温度变化的响应

艾丁湖地处亚洲中部极端干旱区,夏季酷热,地势闭塞,环境条件独特。本研究在该地区选择3个具有不同水分特征和盐角草(Salicornia europaea)种群特征的样地(A样地:地形偏高,4月之后地表无积水,盐角草密度相对较低;B样地:位于地表径流覆盖范围内,地表长期有积水,种群密度相对中等;C样地:地表早期有积水,种群密度相对最大,盖度最高)进行调查,根据盐角草的生长情况,从3月至10月每月调查1~2次,共10次,每次统计样方内盐角草的株数。利用动态生命表以及相关性分析的方法来研究该地区盐角草种群变化及其与环境温度之间的关系。结果表明,艾丁湖盐角草种群密度在5月前基本呈增长状态,5月末至6月由于温度升高、水分下降和营养物质减少引发了种群自疏,出现第1次死亡率高峰期;7月至8月,A、B两个种群出现第2次死亡率高峰期,主要原因是连续长达34d的40℃以上的极端高温;9月A种群出现第3次死亡率高峰期,主要原因可能是高温以及高温加速土壤水分蒸发引起的土壤返盐、水分丧失,从而导致的高温胁迫和盐胁迫。相关性分析表明,A、B种群死亡率与高温显著相关(P0.05)。C种群仅有一次死亡率高峰期,且与温度相关不显著(P0.05),与A、B种群差异较大的原因可能是由于C样地水分条件好、种群密度高缓解了高温的胁迫作用。A、B两个种群存活曲线属于Deevy-Ⅲ型,即初期死亡率较高,9月之后趋于稳定;C种群属于Deevey-Ⅱ型存活曲线,呈对角线型,即各个龄级存活率基本一致。

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 toDeevey type Ⅱ,which shows the same mortality rate at all times in a year.