Canopy Interception Characteristics Of Four Vegetation Types And Their Effect On Groundwater Recharge In Gongga Mountain

Taking the Gongga Mountain National Nature Reserve as study area and taking rainfall grade as mainly impact factor, canopy interception, forest precipitation, stem interception, stem flow and their impact factors are studied by long-term fixed position observation method and in-situ test method .The characteristics of rainfall redistribution and cases of infiltration are explored. This paper lays a foundation for scale Transformation of water cycle process in Gongga Mountain. The main results are as follows:(1) In the region of Mature coniferous forest and Immature coniferous forest the annual precipitation is 2224.56mm during the observation period. Concentrating period of precipitation is April to October and the precipitation is 94.16 percent of annual precipitation. The canopy interception is 706.89mm and the rate of it is 71.46% in the region of Immature coniferous forest. The forest precipitation is 268.88mm and the rate of it is 27.18%. The stem flow is 13.46mm and the rate of it is 1.36%; In the region of mixed coniferous and broadleaf deciduous forest the annual precipitation is 1499.7mm. Concentrating period of precipitation is April to October and the precipitation is 92.23 percent of annual precipitation. In this area the canopy interception is 564.64mm and the rate of it is 45.50%. The forest precipitation is 561.49mm and the rate of it is 54.09%. The stem flow is 4.30mm and the rate of it is 0.41%.In the region of broadleaf forest the annual precipitation is 1115.3mm. Concentrating period of precipitation is April to October and the precipitation is 92.78 percent of annual precipitation. The order of precipitation is coniferous (Mature and Immature)> mixed coniferous and broadleaf deciduous forest> broadleaf forest(2) In immature coniferous forest and mixed coniferous and broadleaf deciduous forest, the canopy interception increases with rainfall. When the precipitation is small, the rate of canopy interception is larger. With the precipitation increasing, it gradually decreases and tends to be steady finally. The forest precipitation and the rate of it increase with rainfall increasing; The steam flow increases with rainfall; the rate of it decreases with rainfall increasing in immature coniferous forest and the rate of it increases with rainfall increasing in mixed coniferous and broadleaf deciduous forest. By regression analysis,the relationship between the interception and precipitation grade is power function; the relationship between the rate of interception and precipitation grade is logarithmic function;the forest precipitation , the rate of forest precipitation, the stem flow and the rate of stem flow have a power function relationship with precipitation grade;(3) The spatial distribution features of forest precipitation has significantly directivity. By comparative with veagtation in CDUT, the main reason of this phenomenon is slope effect. By analyzing date in immature coniferous forest and mixed coniferous and broadleaf deciduous forest, we can speculate the data in Mature coniferous forest and Broadleaf forest. The order of the rate of canopy interception of the four stand types is: Immature coniferous forest> Mixed coniferous and broadleaf deciduous forest> Broadleaf forest>Mature coniferous forest. The order of the rate of forest precipitation of the four stand types is: Mature coniferous forest> Broadleaf forest> Mixed coniferous and broadleaf deciduous forest> Immature coniferous forest. The order of the rate of steam flow of the four stand types is: Mature coniferous forest> Immature coniferous forest>Mixed coniferous and broadleaf deciduous forest>Broadleaf forest.(4) The stem unit area interception and stem unit area lag time decrease with DBH increasing. They have a power function relationship with DBH. The order of Stem unit area interception of the four vegetation types is: Mature coniferous forest> Immature coniferous forest>Broadleaf forest.> Mixed coniferous. The order of Stem unit area lag time of the four stand types is: Mature coniferous forest> Immature coniferous forest>Broadleaf forest > Mixed coniferous and broadleaf deciduous forest.(5) The result of water balance method considering canopy interception and ground water level dynamic analysis method is 0.3696 and 0.2617 respectively.The result of water balance method in hydrogeology is 0.8328.