Water use patterns of co-occurring C-3 and C-4 shrubs in the Gurbantonggut desert in northwestern China
Water use patterns of co-occurring C-3 and C-4 shrubs in the Gurbantonggut desert in northwestern China
复制标题
西北古尔班通古特沙漠共生C-3和C-4灌木水分利用模式
DOI：
10.1016/j.scitotenv.2018.03.307
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发表时间：
2018
影响因子：
9.8
通讯作者：
Wei Sun
中科院分区：
文献类型：
--
作者：
Bahejiayinaer Tiemuerbieke;Xiao-Jun Min;Yong-Xin Zang;Peng Xing;Jian-YingMa;Wei Sun
在水分有限的生态系统中，水源的时空分配是促进植物生存和降低共存植物竞争强度的重要机制。深入了解物种特异性根功能可塑性和变化的水分条件下共存植物的水源差异，可以帮助准确预测沙漠生态系统对未来气候变化的反应。利用土壤水、地下水和木质部水的稳定同位素，研究了古尔班通古特沙漠6种C3和C4灌木水源的季节性、种间和种内差异变化。我们还测量了茎水势，以确定不同水分条件下每个物种的水分胁迫水平。所研究的灌木表现出相似的季节性吸水模式，即，所有灌木在早春提取由融雪水补给的浅层土壤水，并在干燥的夏季恢复到较深的水源，这表明所有研究的灌木具有二型根系，使它们能够获得不同空间和时间的水源。C4灌木群落中的物种表现出不同的季节性水分吸收和水分状况，由于地形和生根深度的差异，表现出不同的适应水分供应和水分胁迫。梭梭（Haloxylonammodendron）和T. C3/C4混合群落中的4种植物在水分提取方面具有相似性，但在水势方面存在差异，表明植物水分状况受根系功能和地上部生理生态特性的共同控制。在C3灌木群落中，两种柽柳根系吸水量和水分状况相似，说明在相同土壤水分条件下，两种柽柳根系功能和生理表现趋同。梭梭在不同的群落中，夏季水分提取量存在差异，表明梭梭在不同土壤水分条件下，其根系深度具有可塑性。
In water-limited ecosystems, spatial and temporal partitioning of water sources is an important mechanism that facilitates plant survival and lessens the competition intensity of co-existing plants. Insights into species-specific root functional plasticity and differences in the water sources of co-existing plants under changing water conditions can aid in accurate prediction of the response of desert ecosystems to future climate change. We used stable isotopes of soil water, groundwater and xylem water to determine the seasonal and inter- and intraspecific differences variations in the water sources of six C3 and C4 shrubs in the Gurbantonggut desert. We also measured the stem water potentials to determine the water stress levels of each species under varying water conditions. The studied shrubs exhibited similar seasonal water uptake patterns, i.e., all shrubs extracted shallow soil water recharged by snowmelt water during early spring and reverted to deeper water sources during dry summer periods, indicating that all of the studied shrubs have dimorphic root systems that enable them to obtain water sources that differ in space and time. Species in the C4 shrub community exhibited differences in seasonal water absorption and water status due to differences in topography and rooting depth, demonstrating divergent adaptations to water availability and water stress. Haloxylon ammodendron and T. ramosissima in the C3/C4 mixed community were similar in terms of seasonal water extraction but differed with respect to water potential, which indicated that plant water status is controlled by both root functioning and shoot eco-physiological traits. The two Tamarix species in the C3 shrub community were similar in terms of water uptake and water status, which suggests functional convergence of the root system and physiological performance under same soil water conditions. In different communities, Haloxylon ammodendron differed in terms of summer water extraction, which suggests that this species exhibits plasticity with respect to rooting depth under different soil water conditions.