鄂尔多斯高原3种固沙灌木水分利用效率的时空变化特征

Spatial-temporal variation of water use efficiency in three species of sand-fixing shrubs on the Ordos Plateau

为评价固沙植物北沙柳(Salix psammophila)、黑沙蒿(Artemisia ordosica)和柠条锦鸡儿(Caragana korshinskii)在不同水热梯度上的适应性,分别在鄂尔多斯市达拉特旗、乌审旗和榆林市靖边县境内设置固定样地,测定了上述3种固沙植物7-9月叶片碳稳定同位素组成(δ^(13)C)和水分利用效率(WUE),分析不同类型固沙植物WUE与气温、降雨量和干旱指数(AI)之间的关系。结果表明:(1)柠条锦鸡儿叶片δ^(13)C和WUE最高,北沙柳次之,黑沙蒿最低,且7月份3种固沙植物叶片δ^(13)C和WUE均显著高于8和9月份;(2)北沙柳叶片δ^(13)C和WUE随着AI的增加无显著差异,而AI最高的达拉特旗,柠条锦鸡儿和黑沙蒿叶片δ^(13)C和WUE显著高于乌审旗和靖边县;多因素方差分析结果表明,固沙植物种类及其所处空间差异对植物叶片δ^(13)C和WUE的影响最大;(3)线性回归分析结果表明,除柠条锦鸡儿WUE对气温变化无显著响应外,气温、降雨量和AI均显著影响了植物WUE。其中,柠条锦鸡儿WUE对AI变化的响应最为敏感,北沙柳对气温变化的响应更为敏感,而黑沙蒿WUE对上述环境因子变化的响应较平稳。

Aims To evaluate the adaptability of Salix psammophila,Artemisia ordosica and Caragana korshinskii to different hydrothermal gradients.Methods In this paper,fixed sample plots were established in the areas of Dalad Banner and Uxin Banner,Ordos City and Jingbian County,Yulin City,respectively,to study the carbon stable isotope composition(δ^(13)C)and water use efficiency(WUE)of the leaves of the above three types of sand-fixing plants during the months of July to September,and to analyze the relationships between the WUE of the different types of sand-fixing plants and air temperature,precipitation and aridity index(AI).Important findings The results showed that:(1)Theδ^(13)C and WUE values were highest in C.korshinskii,and lowest in A.ordosica,and these values were significantly higher in July than in August and September;(2)for Salix psammophila,leaf δ^(13)C and WUE did not exhibit a systematic trend with the increase in AI,while in Dalad Banner,where AI was the highest,leafδ^(13)C and WUE were significantly higher than Uxin Banner and Jingbian County in C.korshinskii and A.ordosica;the results of multifactorial ANOVA showed that the plant species and the spatial differences in which they were located had the greatest influence on plantδ^(13)C and WUE;(3)The results of linear regression analysis showed that air temperature,precipitation and AI significantly affected WUE,except for C.korshinskii WUE,which had no significant effect on air temperature changes.among them,C.korshinskii WUE was the most sensitive to changes in AI,S.psammophila was more sensitive to changes in air temperature,while WUE of A.ordosica had a smoother response to changes in the above environmental factors.