Variation of water use efficiency across seasons and years: Different role of herbaceous plants in desert ecosystem
Variation of water use efficiency across seasons and years: Different role of herbaceous plants in desert ecosystem
复制标题
水分利用效率随季节和年份的变化：草本植物在沙漠生态系统中的不同作用
DOI：
10.1016/j.scitotenv.2018.08.035
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发表时间：
2019
影响因子：
9.8
通讯作者：
Cieraad Ellen
中科院分区：
文献类型：
--
作者：
Liu Ran;Li Yan;Wang Yugang;Ma Jie;Cieraad Ellen
沙漠生态系统通常由木本植物和草本植物两个不同的层次构成。群落组成的变化改变了裸地、木本和草本植物的覆盖率，对水和碳通量有潜在影响。采用涡度相关法和小室法对两个相似的灌木荒漠群落（柽柳群落和哈龙群落）的生态系统水分利用效率（EWUE）（将整个生态系统EWUE区分为EWUEE，将灌木层和草本层EWUE区分为EWUEShrubandEWUEHerb）的年际和年内变化进行了研究。在柽柳群落中，11年的碳通量和水通量结果表明，草本植被覆盖度较大的年份（灌木-草本植被年）的EWUEE显著高于草本植被覆盖度较低的年份（灌木年），其值分别为1.07 ± 0.11和0.68 ± 0.03 g C/kg H2O。EWUEE与草本植物最大盖度呈显著正相关。在Haldalon群落中，灌木层对系统总生态系统生产力（GEP）和蒸散量（ET）的贡献最大，草本层在生长季初期的贡献约为30%，在生长季中期和末期的贡献几乎为零。灌木层EWUE在整个生长季均显著高于草本层EWUE（1.82 ± 0.11 vs.1.06 ± 0.32 g C/kg H2O）。灌木年EWUE与EWUEE呈正相关，灌木年EWUE与EWUEE无相关性。这项研究表明，在这些沙漠生态系统中，草本层的季节和年份的变化对于预测灌木为主的沙漠生态系统中正在进行和预计的气候变化情景下的水和碳循环至关重要。
Desert ecosystems often structured in two distinct layers of woody and herbaceous plants. Changes in community composition alter the fractional coverage by bare soil, woody and herbaceous plants, with potential effects on water and carbon fluxes. We used eddy covariance measurements and chamber method in two similar shrub-dominated desert communities (Tamarixcommunity andHaloxyloncommunity) to assess inter- and intra-annual variations of ecosystem water use efficiency (EWUE) (where we distinguished whole ecosystem EWUE as EWUEE, and EWUE of shrub and herbaceous layers as EWUEShruband EWUEHerb) in central Asia. In theTamarixcommunity, 11 years of carbon and water fluxes showed that years with larger herbaceous cover (referred to as shrub-herb years) had significant higher EWUEEthan years with lower herbaceous cover (referred to as shrub years), with the values of 1.07 ± 0.11 vs. 0.68 ± 0.03 g C/kg H2O. There was a significant positive correlation between EWUEEand the maximum herbaceous plants cover. In theHaloxyloncommunity, chamber measurements during a shrub year demonstrated that the shrub layer contributed most to the gross ecosystem productivity (GEP) and evapotranspiration (ET) of the system, with the herbaceous layer contributing around 30% at the beginning of the growing season, and decreasing to nearly zero during the middle and at the end of the growing season. The shrub layer EWUEShrubwas significant higher than that in the herbaceous layer (EWUEHerb) throughout the growing season (1.82 ± 0.11 vs. 1.06 ± 0.32 g C/kg H2O). EWUEShrubwas positively correlated with EWUEE, but there was no relationship between EWUEHerband EWUEEin a shrub year. This study shows that the variability of the herbaceous layer across seasons and years in these desert ecosystems is crucial for predicting water and carbon cycling under ongoing and projected climatic change scenarios in shrub-dominated desert ecosystems.