State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; Fukang Station of Desert Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Fukang 831500, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; Fukang Station of Desert Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Fukang 831500, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2023 Dec 15;904:166945. doi: 10.1016/j.scitotenv.2023.166945. Epub 2023 Sep 10.
The increasing frequency of drought and decline in groundwater levels are causing ecophysiological changes in woody plants, particularly in desert ecosystems in arid regions. However, the combined effects of meteorological and hydrological droughts on perennial desert plants, especially phreatophytes, remain poorly understood. To address this knowledge gap, we conducted a 5-year precipitation exclusion experiment at two sites with contrasting groundwater depths in the Gurbantunggut Desert located in northwest China. Our study aimed to investigate the impacts of precipitation exclusion and groundwater depth decline on multiple traits of H. ammodendron. We found that long-term precipitation exclusion enhanced midday leaf water potential, stomatal conductance, chlorophyll content, root nonstructural carbohydrates concentration, leaf starch concentration, but decreased water use efficiency. Groundwater drawdown decreased predawn and midday leaf water potentials, maximum net photosynthetic rate, stomatal conductance, Huber value, stem water δO, but enhanced water use efficiency and branch nonstructural carbohydrates concentration. A combination of precipitation exclusion and groundwater depth decline reduced Huber value, but did not show exacerbated effects. The findings demonstrate that hydrological drought induced by groundwater depth decline poses a greater threat to the survival of H. ammodendron than future changes in precipitation.
干旱频率的增加和地下水位的下降正在导致木本植物发生生理生态变化，特别是在干旱地区的沙漠生态系统中。然而，气象和水文干旱对多年生沙漠植物，特别是地下水植物的综合影响仍知之甚少。为了填补这一知识空白，我们在中国西北部的古尔班通古特沙漠的两个具有不同地下水位深度的地点进行了为期 5 年的降水排除实验。我们的研究旨在调查降水排除和地下水位下降对 H. ammodendron 多种特性的影响。我们发现，长期的降水排除会增强中午叶片水势、气孔导度、叶绿素含量、根非结构性碳水化合物浓度、叶片淀粉浓度，但会降低水分利用效率。地下水下降会降低清晨和中午叶片水势、最大净光合速率、气孔导度、Huber 值、茎水 δO，但会提高水分利用效率和枝条非结构性碳水化合物浓度。降水排除和地下水位下降的结合会降低 Huber 值，但没有表现出加剧的影响。研究结果表明，地下水位下降引起的水文干旱对 H. ammodendron 的生存构成的威胁大于未来降水变化。
