太湖流域春季不同土地利用类型蒸散速率的比较

Comparison Study on Evapotranspiration Characteristics of Different Landuse Types in Taihu Lake Watershed

运用静态箱/红外气体分析仪法(static chamber/IRGA),研究了太湖流域茶园、油菜地、小麦地和撂荒地4种不同土地利用类型春季蒸散速率的变化特征,分别对3—5月不同生育期以及6:00—15:00不同时段4种土地利用类型蒸散速率进行了比较。结果表明,太湖流域春季不同土地利用类型蒸散速率总体呈现逐渐增大的趋势,但茶园修剪后蒸散速率大幅下降(36.73%),油菜地在始花期亦突现一峰值〔2.14mmol/(m2·s)〕;4种土地利用类型蒸散速率的日变化呈以12:00—15:00为峰值的单峰曲线,但茶园修剪后蒸散速率的日变化平缓,油菜地和小麦地蒸散速率的日变化幅逐渐增大。4种土地利用类型3—5月蒸散速率日均值从大到小依次为:茶园〔2.24mmol/(m2·s)〕>油菜地〔1.48mmol/(m2·s)〕>小麦地〔1.28mmol/(m2·s)〕>撂荒地〔1.16mmol/(m2·s)〕;3月下旬12:00—15:00,以及4月中旬9:00—15:00为茶园蒸散速率极显著高于油菜地、小麦地和撂荒地的关键时期,差异最大。

Water vapor concentration for different landuse types （tea garden, rape field, wheat field, and fal low land） in the Taihu Lake watershed was measured using static chamher/IRGA method. Diurnal （6：00 ：15：00） and monthly variations of evapotranspiration were compared among these landuse types. In the monthly evapotranspiration analysis, increasing trends of evapotranspiration rates were observed for all the four landuse types in spring. However, evapotranspiration rate for tea garden decreased by 36. 73%after pruning and peak evapotranspiration rate for rape field [2.14 mmol/（m2 . s）] appeared in early flowering stage. Diurnal variations of evapotranspiration rates for these four landuse types showed single peak curves, which reached a maximum value between 12：00 and 15：00. However, diurnal variation of evapotranspiration rate for tea garden became little after pruing, while diurnal variations of evapotranspiration rates for rape field and wheat land increased with the growing stages of rape and wheat. Daily mean values of evapotranspi ration rates of the four landuse types were in the order of tea garden [2.24 mmol/（m2 . s）] rape field [1.48 mmol/（m2 .s）] 〉 wheat land [1.28 mmol/（m2 . s）] 〉 fallow land [1.16 mmol/（m2 . s）]. Between 12：00 and 15：00 in late March and between 9：00 and 15：00 in late April, evapotranspiration rate of tea gar den was significantly greater than those of rape field, wheat land and fallow land.