该研究以塔里木河流域进行实地野外研究,选取典型荒漠河岸林植物胡杨为研究对象,设置5个不同地下水埋深梯度(0~2 m,2~4 m,4~6 m,6~8 m,8~10 m)。通过测定不同地下水埋深梯度下的胡杨生理指标(MDA、PAL、叶片含水率、叶绿素)和叶片反射光谱进行分析。结果显示:随地下水埋深的增大,叶片含水率与MDA含量的变化呈先下降后上升趋势,而叶绿素密度与PAL活性的变化则呈先上升后下降趋势;MDA含量与PAL活性大小均对地下水埋深变化较敏感,同时,低埋深下可能产生的盐胁迫对于植物影响大于干旱胁迫影响,对于埋深0~2m处叶绿素密度和MDA含量都产生较大的影响,但叶片含水率在5个埋深下的差异较小;在350~900nm波段,胡杨具有“一峰两谷”的特征,在“蓝谷”处,不同埋深下胡杨反射率大小顺序:4~6m>0~2m>6~8m>8~10m>2~4m;“绿峰”处,不同埋深下胡杨反射率大小顺序:4~6m>6~8m>0~2m>8~10m>2~4m,与“红谷”处的差异一致;通过生理指标与光谱的相关分析,在波长429nm之后,原始光谱与叶片含水率均达到极显著负相关,在波长645nm处达到负相关的最大值(r为-0.605 30),总体变化幅度较小;但叶绿素密度与光谱在红边710nm处有相关系数最大值(r为-0.636 55)。胡杨光谱的“三边”参数黄边位置在不同埋深时的差异较大,叶片含水率与红谷幅值达到极显著水平,相关性最强(r为-0.577)。这些指标的变化特征及光谱曲线的变化特征,旨在为胡杨抗旱性的研究与鉴定及干旱区植被恢复提供一定的依据。

The study was conducted in the field in the Tarim River basin,with a typical desert riparian forest plant,Populus euphratica as the study object and set five different groundwater depth gradients (0~2 m,2~4 m,4~6 m,6~8 m and 8~10 m). Physiological indicators (MDA,PAL,leaf water content,chlorophyll) and leaf reflectance spectra were analyzed by measuring Populus euphratica under different groundwater burial depth gradients. The results showed that the changes of leaf water content and MDA content tended to decrease at first and increase afterwards with increasing depth of groundwater burial,while the changes of chlorophyll density and PAL activity tended to increase at first and decrease afterwards. Both MDA content and PAL activity magnitude were more sensitive to changes in groundwater burial depth,while the possible salt stress at low burial depths had a greater effect on plants than drought stress,and had a greater effect on chlorophyll density and MDA content at burial depths of 0~2 m. However,the differences in leaf water content at the five burial depths were small. In the 350~900nm band,poplar had the characteristics of "one peak and two valleys". In the "blue valley",the order of poplar reflectance at different burial depths was: 4~6m>0~2m>6~8m>8~10m>2~4m. At the "Green Peak",the order of poplar reflectance at different depths was: 4~6m>6~8m>0~2m>8~10m>2~4m,which was consistent with the difference at the "Red Valley". By correlation analysis of physiological indexes and spectra,the original spectra and leaf water content all reached a highly significant negative correlation after the wavelength of 429 nm,and reached the maximum value of negative correlation at the wavelength of 645 nm (r of -0.60530),with a small overall change. However,the correlation coefficient between the chlorophyll density and the spectrum had a maximum at 710nm on the red side (r of -0.63655). The "trilateral" parameters of the poplar spectra varied greatly at different depths of burial,and the water content of the leaves reached a highly significant level with the red valley amplitude,with the strongest correlation (r of -0.577).The variation characteristics of these indicators and spectral curves are intended to provide some basis for the research and identification of drought resistance of Populus euphratica,and the construction of ecological environment and vegetation restoration in arid areas.