海南岛尖峰岭热带森林蒸散

EVAPOTRANSPIRATION WATER-COMSUMPTION IN TROPICAL FOREST AT JIANFENGLING, HAINAN ISLAND

本文用能量平衡-波文比法在海南岛尖峰岭地区对热带森林的蒸散进行三年早季和雨季49d的测定,测定数据用逐步回归法建立多元回归方程,把降雨量作为因变量置于回归方程中,引进新参数AWE表示可供蒸散的水分,计算出森林全年蒸散量,并用Penman-Monteith方程作对比,分别计算出森林每日蒸散值。其结果是:用EBBR法测定和计算的森林全年蒸散值分别为534.7mm(1983年)、520.7mm(1984年)和564.0mm(1985年),分别占年降雨量的30.4％、30.2％和44.9％。而用Penman-Monteith方程计算的森林全年蒸散值分别为721.1mm(1983年)、714.8mm(1984年)和728.4mm(1985年),分别占年降雨量的41.0％、41.5％和58.0％。用这两种方法计算的日平均蒸散的最小值分别是0.36mm和0.49mm,日平均蒸散的最大值分别为2.55mm和3.14 mm。

Based on the improvements of observing methods in 1980-1981, the evapotranspiration experiment in a tropical monsoon forest was conducted using EBBR method on Hainan Island from 1983 to 1985 during which 49 sampled days in dry seasons and rainy seasons were selected at random. A stepwise multiple regression was set up using the daily evapotranspiration values and the synoptic data which were recorded daily from a meteorological station 1 km away from the Research Station of Tropical Forestry. The rainfall was taken into consideration in the regession equations by using especially designed index 'Available Water for Evaporation' (AWE). As comparison, the every day EPT values were calculated using Penman-Monteith equation. The computed results turned to be 534.7mm, 520.7mm and 564.0 mm according to EBBR method; and 721.1 mm,714.8 and 728.4 mm according to Penman-Monteith equation for 1983, 1984 and 1985 respectively. The EPT/ rainfall ratios were 30.4% 30.2% and 44.9% with EBBR method; and 41.0 %, 41.5 % and 58.0 % with Penman-Moneith equation for 1983, 1984 and 1985 respectively. The ratios were strongly correlated with intensities of rainfall. The larger the intensities of rainfall, the smaller the rater consumption percent (EPT/rainfall) because of the greater runoff. The minimun average daily EPT values were 0.36 mm/d and 0.49mm/d by the two methods respectively; and the corresponding maximum average daily EPT values were 2.55mm/d and 3.14mm/d respectively.