Partitioning water source and sinking process of a groundwater-dependent desert plant community
Partitioning water source and sinking process of a groundwater-dependent desert plant community
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依赖地下水的沙漠植物群落的水源划分和下沉过程
DOI：
10.1007/s11104-018-3714-6
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发表时间：
2018-09-01
期刊：
影响因子：
4.9
通讯作者：
Li, Yan
中科院分区：
文献类型：
--
作者：
Liu, Ran;Wang, Yugang;Li, Yan
荒漠植物群落通常分为木本植物和草本植物两层。在这个水资源有限的生态系统中，水源的划分和下沉过程仍然是一个关键的不确定性。我们的目标是将蒸散（ET）组分划分为裸露土壤、灌木和草本植物的水分损失；估算地下水对蒸散发和灌木层蒸腾的贡献（T（灌木））；确定中亚地下水依赖型荒漠植物群落ET组分的主要驱动因素。利用涡动相关系数、静态室和微型渗蒸仪测量蒸散发及其组分（蒸腾和蒸发）。采用氧稳定同位素和IsoSource模型对优势灌木梭梭（Haloxylon ammodendron）水源进行了测定。草本层蒸腾(T)与灌木层蒸腾(T)的季节分布有显著差异。T（草本）在生长季开始时达到最大值，在生长季中期和结束时降至接近零。相反，T（灌木）能够维持整个生长季节，由于深根接触地下水。灌木林T（灌木）、草本植物T（草本）和蒸发量E (E)分别为70、16和82 mm a(-1)，分别占2014年总ET的42、9和49%。地下水主要被T（灌木）消耗（51 mm -1），占T（灌木）的73%。地下水对ET的贡献为60 mm a(-1)，占2014年总ET的35%以上。T（灌木）、T（草本）和E的季节动态受不同驱动因素的影响：T（灌木）：气温；T（草本）：土壤含水量和草本植物覆盖度；E：净辐射和降水。该研究表明，更好地了解ET的来源和沉降过程对于预测正在发生和预测的气候变化情景下地下水依赖性荒漠植物群落的水文响应至关重要。
Desert plant community is often structured in two distinct layers of woody and herbaceous plants. Partitioning its water source and sinking process remains a key uncertainty in this water-limited ecosystem. Our aims are to partition the evapotranspiration (ET) components into water loss from bare soil, shrub, and herbaceous plants; estimate the contributions of groundwater to ET and shrub layer transpiration (T (shrub)); and determine the major drivers of ET components in a groundwater-dependent desert plant community in Central Asia.Eddy covariance, static chambers, and micro-lysimeters were used to measure ET and its components (transpiration and evaporation). Oxygen stable isotope and IsoSource model were used to determine the water source of dominant shrubs (Haloxylon ammodendron).The seasonal pattern of transpiration (T) for the herbaceous layer (T (herb)) differed markedly from that for T (shrub). T (herb) reached the maximum values at the beginning of the growing season, and then decreased to nearly zero at the middle and end of the growing seasons. Conversely, T (shurb) were able to maintain throughout the growing season due to the deep root access to groundwater. In total, T (shrub), T (herb), and evaporation (E) were 70, 16, and 82 mm year(-1), they account for 42, 9, and 49% of total ET during 2014. Most of the groundwater was consumed by T (shrub) (51 mm year(-1)), accounted for 73% of T (shrub). The contribution of groundwater to ET was 60 mm year(-1), representing more than 35% of total ET during 2014. The seasonal dynamics of T (shrub), T (herb), and E were shaped by different drivers: T (shrub): air temperature; T (herb): soil water content and herbaceous plant cover; E: net radiation and precipitation.This study demonstrated that a better understanding of the source and sinking process of ET is crucial for predicting hydrological response under ongoing and projected climatic change scenarios in a groundwater-dependent desert plant community.