| Guan Ting Reservoir area is one of the main water source areas for Beijing, so that to strengthen the construction of water conservation forest would be having great significance for the ecological environment of water source area. Moreover, to study the hydrological charaters will provide the scientific evidence for vegetation restoration and comprehension management of this area. The paper is the part of reports of "Study on the earring capacity of soil water and the mechanism of the vegetation restoration in Guan Ting Reservoir area", which was supported by Beijing Natural Science Fund Committee. In order to facilitate the vegetation restoration in this area, the relations between forest vegetation and water (precipitation and soil water) as well as the interaction mechanism among different water factors, overed the priority research papers and based on the nature conditions, were discussed by means of studying on the main forest charaters in Shangxinzhuang small watershed. The main purpose of the study is to provide the theory foundation and scientific evidence when earring out forestry eco-engineer construction and selecting optimum pattern of vegetation restoration. Some main conclusions in this study are as follows:(1) With the studying of Robinia pseudoacacie and Populus simonii plantations, it is showed that the rainfall intercreption of forest canopy were both influenced by the charater of rainfall and forest canopy structure. And different combinations between rainfall intensity and precipitation can lead to different interception. But there is a maximal interception (15cm) in the two tree species plantations, which means the rainfall interception would not increase when it reachs the maximum point. The canopy density, on the other hand, is in direct proportion with its interception or in inverse proportion with throughfall.(2) Through observed to the two tree species forest lands, the runoff will only take place when the precipitation is more than 5mm or the rainfall intensity is over 4mm/h, of which the precipitation and runoff have a liner correlation (R=0.8). Also, land slope has increased effect on runoff, but the different coverage of vegetation can partly counteract the effect, which indicated that surface rough degree is one of the important factors to runoff.(3) It demonstrated that the potential evaporation of the two tree species plantations both higher than the precipitation in reseach period, of which the air temperature and air relative moisture are two main factors to evaporation. The ratio of P/E in the two plantations is lower than out of the plantations, and it is increasing withthe canopy density. The transpiration of the wood is the biggest parts in the evapotranspiration and the value is deeply influened by the precipitation and other meteorological factors.(4) There are the same variation rules in research period, both soil water and rainfall monitored, but the soil water was varied by different depth of soil, canopy density and rainfall charators, of which the air temperature and air relative moisture play the most important roles on it. Although the soil water in different depth have a similar varieties, the various range are different, of which the surface layers of soil, i.e. 0~20cm, is the most. The depth, however, is the most important factor for soil water content, and there is significact different between the surface layer and the deep layer, but the difference, on the other hand, is guadually change.(5) It is showed that the water content, in rainy season, were varied by rainfall, especially surface layer (0~20cm) varing from 5% to 20%, but the effect of it were decreasing smoothly along with the depth increasing. Also, the precipitation strength and initial soil water content have deeply affected on water content that when it has being monitored.
|
PDF Full Text Request