黑河中游荒漠绿洲过渡带多枝柽柳对地下水位变化的生理生态响应与适应  

Ecophysiological responses and adaptation of Tamarix ramosissima to changes in groundwater depth in the Heihe river basin

作　　者：张佩[1,2] 袁国富[1] 庄伟[1,2] 薛沙沙[1,2] 

机构地区：[1]中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室,北京100101 [2]中国科学院研究生院,北京100049

出　　处：《生态学报》2011年第22期6677-6687,共11页Acta Ecologica Sinica

基　　金：国家重点基础研究发展规划项目(973项目)(2009CB421305;2010CB951002)

摘　　要：以黑河中游荒漠绿洲过渡带主要建群种多枝柽柳成年体为研究对象,对野外不同地下水埋深处柽柳叶片生理生态特性进行观测和分析,评价分析多枝柽柳对地下水埋深差异和地下水位季节变化的响应过程和适应机制。结果显示:在相似大气环境条件下,不同地下水埋深之间,多枝柽柳叶片的生理生态指标没有明显差异,但对于地下水位的季节波动,则表现出较为明显的变化和响应;柽柳通过气孔的调节,在更深地下水埋深下,水分条件更差时,保持了稳定的气孔导度和较高的叶片胞间二氧化碳浓度,从而维持相对稳定的碳同化能力及较高水分利用效率,表现出较好的适应能力;在不同地下水埋深下,叶片生理生态指标随地下水位下降的响应特征呈现出明显差异,这种差异暗示了黑河中游荒漠绿洲过渡带多枝柽柳的适宜地下水位在3 m左右。Areas in middle reaches of the Heihe river basin constitute a desert oasis ecotone.The normal growth of vegetation in this area is significantly affected by irrigation practices and seasonal groundwater level fluctuations.This is particularly true for groundwater dependent species.The continued decline of the groundwater level,due high levels of groundwater consumption for agricultural irrigation in the area,threatens the stability and sustainability of this transitional ecosystem.A field experiment was conducted on Tamarix ramosissima,one of the main species of this desert-oasis ecotone,to elucidate the response processes and adaptation mechanisms of this species to changes in groundwater depth.The groundwater depth differences examined included two conditions： spatial differences in absolute groundwater depth and seasonal fluctuations of the groundwater level.Field measurements were carried out at seven sites,where groundwater depth ranged from 0.75m to 7.05m.A number of leaf ecophysiological indicators were recorded,including,midday leaf net photosynthetic rate（Ps）,transpiration rate（Tr）,stomatal conductance（C）,intercellular CO2 concentration（Ci）,and midday stem water potential（Ψm）.All measurements were made under similar meteorological conditions.The study was conducted from late June to early September.During this period groundwater levels at the different sites fell by differing amounts.The results show that Ps and Tr values among the seven sites were not notably different（the fitted trendline slopes were-0.24 for Ps,and-0.13 for Tr,respectively）,indicating that there was little difference in the growth rates of T.ramosissima among sites with different absolute groundwater depth.However,Ps and Tr showed a clear decline with the main seasonal declines in groundwater level（the fitted trendline slopes were-10.10 for Ps,and-6.34 for Tr,respectively）.These differing responses to changes in groundwater depth suggest that T.ramosissima may be adapted to the different absolute groundw

关 键 词：多枝柽柳 荒漠绿洲过渡带 地下水埋深 光合速率 蒸腾速率 气孔导度 

分 类 号：S793.5[农业科学—林木遗传育种] Q945[农业科学—林学]