The Dynamic Study on Transpiration Consumption of Black Locust Forest

To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2000, with the LI-1600 Steady Porometer and the general weather information. The daily variation of transpiration in black locust forest (Robinia pesudoacacia L.)is modeled by Penman-Monteith equation. As a result of the model, a continuous daily transpiration in the growth season was calculated. The net radiation, intercepted by black locust forest canopy, was acquired from a semi-empirical equation of measuring net radiation R_n with the extinction coefficient k and leaf area index LAI. The canopy integral stomatic resistance is a mimesis with an empirical equation of measuring data. Compared with measuring data, the relative error of the modeled ones is less than 12% averagely. At last, the total transpiration of black locust forest during the period of 1998 and 2000 in the growth season of May to October, as an average transpiration of the different density stands, were 192.46, 187.07 and 195.59 mm respectively.