Simulation Study On Transpiration Of Main Tree Species In Fangshan County Shanxi Province

In view of the deficit of water resources in semi region, with the guidance of SPAC Theory, we studied the Transpiration characteristics and the relationship with the main factor of Platycladus orientalis Ulmus pumila and Pinus tabulaeformis in Beijing Forestry University Forest runoff test site in Tuqiao Ditch Valley, Yukou Town, Fangshan County, west of Lv Liang, Shanxi province. To provide the theoretical basis of Vegetation instauration constructs and the the choice of Planting density in the region. The major findings and conclusions are as follows:In 2009 we calculated the important parameter in revised Penman-Monteith model-the overall canopy stomatal resistance(rsT) with the sap flow meter measured transpiration values, and set up rsT's regression model with the main meteorological factors by small weather station data. Respectively, we simulated transpiration process with small weather station data and Lishi weather station data, by contrast, when calculated with Lishi Weather Station data the simulated value probably 1.7 times than the value with a small weather station, but while a correction factor be multiplied to rsT, the relative error is less than 10% of the two results in sunny days.This article uses the number of days of continuous observations of the rsT regression, not only one day's data. So the regression model can be more applicable, more accurately reflect its variation and consistent with long-term study.The rsT's regression with the meteorological factors by calculated results with Stem flow meter data can be more accurate than the regression with the meteorological factors by the measured data with Li-1600. Through simulation and actual values of the comparison, the overall error of the former approaches is less than 7% and after the way the overall error is less than 12%.The potential evaporation was 465.08mm in the study area during the growing season, the canopy transpiration of Platycladus orientalis Ulmus pumila and Pinus tabulaeformis were separately 169.51mm,214.43mm and 126.63mm, forest water consumption were separately 177.80mm, 236.88mm and 130.56mm. And large water deficit existed in May, June and October, as the potental evaporation were far less than precipitation in the three month.