太湖流域典型土地利用类型生态耗水分量的比较研究

Comparison of Ecological Water Consumption's Components of Typical Land Use Types in Taihu Lake Basin

[目的]对太湖流域典型土地利用类型的生态耗水分量进行比较研究,为优化土地利用结构、提高流域生态系统水量调节能力提供理论基础。[方法]应用田块尺度土壤—水—大气—植物模型(SWAP),在太湖流域水汽通量监测试验基础上对林地、茶园和耕地的生态耗水进行数值模拟。[结果](1)林地蒸腾量占据耗水量的87.80%,在林地生态系统调节水量过程中起着重要作用,生态耗水呈以8月为峰值的单峰曲线;(2)茶园茶株蒸腾和株间蒸发占据耗水的94.86%,两者比值大约为3∶1,茶株的人工修剪对各分量的年内变化有影响;(3)耕地作物蒸腾和棵间蒸发占据了耗水量的94.73%,两者比值约2∶1,并呈现麦季(1—5月)和稻季(6—11月)2个时段特征;(4)流域竹林枯枝落叶层厚,树林冠层厚实,园地茶株由于修剪后枝叶还未恢复,耕地小麦和水稻作物有生长初始阶段,所以林地相比园地和耕地土壤蒸发偏低。[结论]3种不同土地利用类型的植被在不同生长阶段的叶面积指数、人工修剪作用对耗水量年内变化可能也会产生一定的影响。

[Objective]Comparative study on ecological water consumption of typical land use types in Taihu Lake basin was conducted,in order to provide a theoretical basis for optimizing land use structure and improving water regulation capacity of the watershed ecosystem.[Methods]Based on water flux monitoring points,a field scale model,soil-water-atmosphere-plant model(SWAP),was applied to simulate the ecological water consumptions in forest land,tea garden and cultivated land.[Results]①Ecological water consumption in the forest land showed a single peak from June to August,in which tree’s transpiration contributed 87.80%of it,hence it played an important role in regulating the amount of water.②Ecological water consumption in tea garden changed relatively in a flat mode during the year,tea plant transpiration(69.17%)and soil evaporation(25.69%)accounted for the majority of the water consumption together.③Yearly change of ecological water consumption in cultivated land had two obvious different periods,corresponding to wheat season(January to May)and rice growing season(June to November),respectively.Annual transpiration of cultivated land(61.28%)and the evaporation(33.45%)accounted for 94.73%of the water consumption.④The evaporation of forest land was relatively smaller than those of garden and cultivated land.This can ascribed as the following reasons:litter layer and canopy were thick in forest,whereas branch leaves did not recover in tea garden,and crops were at the stages of initial growth.[Conclusion]Annual variance of ecological water consumption was mainly affected by rainfall and temperature,but growth period of crops and tea pruning may also have their impacts on ecological water consumption.