灌丛化的蒸散耗水效应数值模拟研究——以内蒙古灌丛化草原为例

发布时间：2018-02-24 18:21

本文关键词： 灌丛化生态水文效应蒸散发二源模型数值模拟　出处：《植物生态学报》2017年03期 　论文类型：期刊论文

【摘要】：灌丛化是干旱半干旱草原一种常见的全球性变化现象,由于野外土壤、灌丛和草本的蒸散耗水难于拆分的限制,关于灌丛化蒸散耗水效应的研究较少。该文将已有的二源模型应用于我国内蒙古灌丛化草原估算其蒸散发,并用波文比系统观测结果对模型进行了率定。研究结果表明改进的模型可以较好地重建灌丛化草地的蒸散发特征;敏感性分析结果表明模型输入变量及参数对蒸散发组分拆分结果产生的误差较小。在此基础上进行了灌丛化的情景模拟,研究其耗水效应。结果表明:灌丛化对蒸散发总量影响较小,而对蒸散发组分影响较大。灌丛化初期盖度5%、中期盖度15%及后期盖度为30%的情境下,对应的生长季内蒸散发(ET)平均值分别为182.97、180.38和176.72 W·m~( 2);土壤蒸发(E)占蒸散发比率(E/ET)平均值分别为52.9%、53.9%和55.5%。灌丛化从初期到中期、中期至后期,蒸散发降幅平均值分别为0.34%和0.44%,E/ET升幅分别达2.04%及3.25%。该研究结果表明在内蒙古太仆寺旗站点灌丛化导致的土壤水分差异并不明显,但随着灌丛化加剧,灌丛逐渐替代草本,改变了原有的生态系统结构,植被叶面积指数变小,导致冠层导度降低。研究结果强调我国半干旱草原区灌丛化加剧对生态系统总蒸散耗水量影响不大,但其土壤蒸发无效损耗快速增加会导致系统水分利用效率降低。
[Abstract]:Thickedness is a common global phenomenon in arid and semi-arid steppe, due to the difficulty of separating the evapotranspiration of field soil, shrub and herbs. There are few studies on the effect of shrub evapotranspiration. In this paper, the existing two-source model is applied to estimate the evapotranspiration of thicket steppe in Inner Mongolia, China. The results show that the improved model can reconstruct the evapotranspiration characteristics of shrub grassland. The sensitivity analysis results show that the error of model input variables and parameters on the resolution of evapotranspiration components is relatively small. The results showed that thicketization had little effect on the total evapotranspiration, but had a great effect on the evapotranspiration components. Under the conditions of initial coverage of 5, intermediate coverage of 15% and late coverage of 30%, the effects of shrub on the total evapotranspiration were studied. The average values of ETS in the growing season were 182.970.38 and 176.72 W 路m ~ (-1), respectively. The average value of E / E ratio in soil evaporation was 52.9% and 55.55.The average value of thicketization was 52.9% and 55.5%, respectively, from the initial to the middle, and from the middle to the later stage. The average value of the decrease in evapotranspiration was 0.34% and 0.44% E / ET increased by 2.04% and 3.25 respectively. The results showed that the soil moisture difference caused by shrub at Taibusi flag station in Inner Mongolia was not obvious, but with the intensification of shrub, shrub gradually replaced herbaceous. The change of the original ecosystem structure resulted in the decrease of canopy conductance due to the decrease of vegetation leaf area index. The results showed that the intensification of shrub in semi-arid grassland had little effect on the total evapotranspiration of ecosystem. However, the rapid increase of soil evaporation failure will lead to the decrease of water use efficiency of the system.
【作者单位】：北京师范大学地理科学学部资源学院;北京师范大学地表过程与资源生态国家重点实验室;
【基金】：国家自然科学基金(41671019、91425301和41301014) 北京市本科生基金项目
【分类号】：S812

【参考文献】