%0 English Abstract
%T [Environmental regulation of water use efficiency in Artemisia ordosica in Mu Us Sandy Land: From leaf to ecosystem].
%A Zhai SC
%A Wang TJ
%A Li XH
%A Hao SR
%A Jia X
%A Zha TS
%A Liu P
%J Ying Yong Sheng Tai Xue Bao
%V 35
%N 4
%D 2024 Apr 18
%M 38884234
暂无%R 10.13287/j.1001-9332.202404.003
%X Water use efficiency (WUE) is a key indicator for predicting the impacts of climate change on ecosystem carbon and water cycles. Most studies have explored the changes in the response environment of WUE at a particular scale. Few studies have examined how WUE responds to environments at multiple scales, thus limiting our in-depth understanding of the cross-scale carbon and water cycles. In this study, we measured photosynthesis and transpiration in situ periodically and continuously from June to October 2022 in a community dominated by Artemisia ordosica in Mu Us Sandy Land, and analyzed the seasonal variations in WUE at leaf, canopy, and ecosystem scales. The results showed there were significant seasonal variations in leaf water use efficiency (WUEL), canopy water use efficiency (WUET), and ecosystem water use efficiency (WUEE). WUEL was large in June and small in both August and September, ranging from 0.73-2.98 μmol·mmol-1. Both WUET and WUEE were lowest in June and highest in July and August, ranging from 0.10-7.00 and 0.06-6.25 μmol·mmol-1. WUEL was significantly negatively correlated with stomatal conductance. WUET was significantly positively correlated with canopy conduc-tance and soil water content, and negatively correlated with vapor pressure deficit (VPD). There was a significant positive correlation between WUEE and soil water content (SWC10) in 10 cm soil depth. The structural equation model showed that SWC10 and air temperature affected net photosynthetic rate and transpiration rate by modifying stomatal conductance, and thus affecting WUEL. VPD and SWC10 affected WUET by altering transpiration. SWC10, air temperature, and VPD affected WUEE by regulating ecosystem gross primary productivity. The modelling of carbon and water cycles should thoroughly consider the path and intensity of the effect of environmental factors on WUE at multiple scales.<BR>水分利用效率(WUE)是预测气候变化对生态系统碳、水循环过程的关键指标。以往研究多从单一观测尺度对WUE响应环境的变化进行探究,鲜有研究对不同观测尺度WUE如何响应环境进行论述,这限制了对跨尺度碳水循环的深入理解。本研究选取毛乌素沙地优势种黑沙蒿群落,于2022年6—10月,利用固定样地测定与原位连续监测方法对黑沙蒿的光合与蒸腾特征进行观测,分析黑沙蒿叶片、冠层和生态系统水分利用效率季节特征及其环境影响因素。结果表明: 叶片水分利用效率(WUEL)与冠层水分利用效率(WUET)和生态系统水分利用效率(WUEE)的季节变化差异明显。WUEL在6月较大,在8、9月较小,波动范围为0.73～2.98 μmol·mmol-1;WUET和WUEE在6月最小,在7、8月最大,波动范围分别为0.10～7.00和0.06～6.25 μmol·mmol-1。WUEL与气孔导度呈显著负相关;WUET与冠层导度和土壤含水量呈显著正相关,与饱和水汽压差呈显著负相关;WUEE与10 cm土层土壤含水量(SWC10)呈显著正相关。结构方程模型表明,SWC10和空气温度通过调节气孔导度影响净光合速率和蒸腾速率,进而影响WUEL;饱和蒸气压差和SWC10通过调节蒸腾速率对WUET产生影响;土壤含水量、空气温度和饱和蒸气压差通过调节生态系统总初级生产力对WUEE产生影响。未来碳水循环的模型拟合应充分考虑环境因子对不同观测尺度WUE的影响路径与强度。.