鼎湖山顶级森林生态系统水文要素时空规律

运用连续7a(1993～1999)的水文观测资料，对南亚热带顶级生态系统鼎湖山季风常绿阔叶林集水区水文要素时空规律进行分析，得到如下一些主要结论：(1)鼎湖山多年平均降水量为1910mm，湿季降水量占年降水量80％，干季仅占20％。6月份的降水量最大，1月份最小。(2)季风常绿阔叶林冠层截留率为31．8％，湿季的截留量占全年截留量的66．7％，截留量最大值和最小值所在的月份分别为7和1月份。各月的截留率差异很大，截留量大的月份，截留率较低；截留量小的月份，截留率较高。(3)季风常绿阔叶林集水区多年平均总径流量953．0mm，总径流系数49．9％，其中地表径流量为252．3mm，地表径流系数13．2％；地表径流与降水量之间存在二次抛物线型回归关系，与降水强度的关系不大，这说明季风常绿阔叶林的产流形式是是蓄满产流。(4)季风常绿阔叶林多年平均蒸散948．2mm，占同期降水量的49．7％；蒸散力1031．4mm，年蒸散系数为0．92，蒸散月变化规律较降水量的月变化规律有所滞后。(5)系统贮水量的月变化很大，2～8月份，系统处于蓄水阶段；9月份至翌年1月份，系统处于失水阶段。蓄水和失水的最大值分别出现在湿季和干季的第一个月，即4月份和10月份。(6)集水区多年平均水量总输入2129．9mm，实际输入1910mm(降水量)，其中219．9mm的水量输入是由系统贮水量变化而产生。支出的总水量2129．9mm，实际支出1901．3mm(径流和蒸散量)，其中228．6mm的水量支出是由系统贮水量变化引起的。

Spatial and temporal variations of some hydrological factors in a climax forest ecosystem in the Dinghushan region

Although most parts of landscape are arid or desert in the subtropics in the world, the subtropic region of South China is an exception, where monsoon evergreen broad leaf forest, the climax forest ecosystem in the region is conserved. Using field measurements from 1993 to 1999, we analyzed the spatial and temporal variations of some hydrological factors in this climax forest ecosystem. Main results are: (1) the average annual precipitation is 1910 mm, of which 80% is from wet seasons and 20% from dry seasons. The mean monthly precipitation is highest in June and lowest in January; (2) About 31 8% of rainfall is intercepted. Interception during wet season accounts for 66 7% of annual total. Canopy interception is highest in July and lowest in January. The rate of interception decreases within an increase in the amount of rainfall intercepted in the canopy; (3) the annual runoff is 953 0 mm with a coefficient of variation of 49 9%. The amount of annual surface runoff is 252 3 mm with a coefficient of variation of is 13 2%. Variation of annual surface runoff is more closely related to that of annual precipitation than rainfall intensity. (4) Average annual evapotranspiration in the monsoon evergreen broad leaf forest is 948 2 mm, which amounts to 49 7% of annual precipitation. Annual potential evapotranspiration is 1031 4 mm, and is similar to the amount of actual evapotranspiration. Temporal variation of monthly evapotranspiration lags behind that of monthly precipitation;(5) Monthly change in water storage in the ecosystem is significant. The amount of water stored in the catchment increases between February to August, and decreases during remaining months of a year. The increase in water storage of the catchment is highest in April, and the decrease in water storage is highest in October. (6) The mean annual water input to the catchment is 2129 9 mm, of which 1910 mm is from annual precipitation, and 219 9 mm from a change in the water storage. The mean annual total input of water is approximately equal to its output. The mean outputs are 1901 3 mm through runoff and evaportranspiration, and 228 6 mm from the change of water storage.