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基于 3个假说和林冠上方 2m处的气象变量 ,采用Penman Monteith组合模型估算了一个生长季节内川西亚高山林区分别以云杉 (SF)、冷杉 (FF)和白桦 (BF)为优势树种的 3个林分的湿林冠蒸发速率 (Er)。研究结果表明 ,SF、FF和BF的湿林冠蒸发量 (E)分别为 4 4 5mm、88 5mm和 5 7 8mm ,分别占总降雨量的 9 2 %、16 6 %和10 2 %。与SF和BF相比 ,FF具有最高的月平均Er和蒸发比例。SF、FF和BF的平均Er分别为 0 0 97mm/h(变化范围 :0 0 2 8～ 0 4 87mm/h)、0 2 4 2mm/h (变化范围 :0 0 6 8～ 0 711mm/h)和 0 14 9mm/h (0 0 6 0～ 0 5 76mm/h)。最高和最低的月平均Er分别在 6月 (SF、FF和BF分别为 0 12 0mm/h、0 317mm/h和 0 16 9mm/h)和10月 (SF、FF和BF分别为 0 0 83mm/h、0 187mm/h和 0 10 1mm/h)。 8:0 0至 16 :0 0期间的平均Er显著高于0 :0 0至 8:0 0以及 16 :0 0至 0 :0 0期间的平均Er。Er显著的日变化和月变化主要归因于林冠上方的太阳辐射、空气温度和相对湿度的变化
Based on the three hypotheses and the meteorological variables at 2 m above the forest canopy, the Penman Monteith model was used to estimate the spatial distributions of spruce (SF), fir (F) and white birch (BF) The forest canopy evaporation rate (Er). The results showed that the crown evaporation of SF, FF and BF were 44 mm, 88 mm and 578 mm, accounting for 92%, 16 6% and 102% of the total rainfall, respectively. FF has the highest monthly average Er and evaporation ratio compared to SF and BF. The average Er of SF, FF and BF were respectively 0 0 97 mm / h (range 0 0 28 ~ 0 477 mm / h) and 0 2 42 2 mm / h (range 0 0 6 8 ~ 0 711 mm / h ) And 0 14 9mm / h (0 0 6 0 ~ 0 5 76mm / h). The monthly mean Er of the highest and the lowest was respectively 0 0 83 mm, 0 317 mm / h and 0 16 9 mm / h for SF, FF and BF in June (SF, FF and BF, respectively) / h, 0 187 mm / h and 0 10 1 mm / h). The average Er during 8: 0 0 to 16: 0 0 is significantly higher than the average Er during 0: 0 0 to 8: 0 0 and 16: 0 0 to 0: 0 0. Significant diurnal and monthly variations in Er are mainly due to changes in solar radiation, air temperature and relative humidity above the canopy