| In this paper, based on investigation of Nenjiang watershed form characteristics and on located observation of precipitation components, water balance of forest ecosystem was quantitatively analyzed. The function and mechanism of forests on water and soil conservation was probed by investigation of forest litter and soil, and water balance of cropland and grassland were analyzed. At the same time, water balance table of watershed was made according to observation of evapotranspiration and runoff in each ecosystem, and methods of forest management and watershed management in Nenjiang were put forward. Forests have great hydrologic effects. Precipitation is redistributed into crown interception, throughfall and stemflow. Different forest types have different interception values. The results show: (1) the mean crown interception ratio of birch, dahurian birth, broad-leaved mixed forest and larch is 23.39%, 19.78%, 20.19%, 31.65%, respectively; the ratio of throughfall to rainfall is 72.44%, 76.79%, 77.07%, 66.96%, respectively; the ratio of stemflow to rainfall is 3.92%, 3.43%, 2.74%, 1.43%, respectively. (2) Litter maximum water- holding ratio of four forest types and grassland was 258.95%, 201.68%, 256.50%, 205.69%, 262.25,respectively. (3) Evapotranspiration of four forest types, cropland and grassland is 85.32%, 84.71%, 85.08%, 85.08%, 80.02%, 91.60% of total rainfall. (4) Watershed evapotranspiration is 80.84% of precipitation, and streamflow is 23 .26%. Nenjiang watershed should be managed by the theory and method of system engineering and by combination of biological measures and engineering methods and forest in watershed should be managed according to different forest and soil types.
|
PDF Full Text Request