Research On The Water Conservation Function Of Typical Forest In Alpine Region Of Qinghai Datong Country

Baoku river is the main water supply of Heiquan reservoir which is the world’s third largest highland reservoir, and the Heiquan Reservoir is Xining’s main water source which is the provincial capital of Qinghai Province,and which is responsible for60%of the urban water supply. Therefore, the ecological security of the region is of great significance to the healthy development of the social economy of Xining. This paper selects six typical forest vegetation communities in the region as the research object, using a combination of field and laboratory test methods to study its water conservation function. In this paper, using correlation analysis, principal component analysis and so on, respectively, from the forest canopy, litter outer and soil layer of the three-level analyze the water conservation capacity. Finally using entropy method comprehensively evaluate a variety of indicators of different typical forests. This not only provides a theoretical basis for the optimal allocation of local water conservation forest system, while helping to build a sustainable development of forest vegetation in Datong of Qinghai province. This paper mainly gets the following conclusions:(1) In different vegetation communities, species richness of shrub and herb layers exhibits a similar trend. The highest species richness index is Picea asperata Mast mixed Betula platyphylla Suk, Picea asperata Mast mixed Larix principis-rupprechtii and Picea asperata Mast and Larix principis-rupprechtii is the smallest. The overall trend shows:coniferous and broadleaf mixed forest, broadleaf forest, coniferous forest is in descending order. Richness index and species diversity index of herb layer of the same species are larger than the shrub layer, indicating that herbaceous vegetation is in the dominant position in the understory vegetation.(2) The canopy interception capabilities of six kinds of forest are:Picea asperata Mast mixed Larix principis-rupprechtii (43.18%)> Picea asperata Mast mixed Betula platyphylla Suk (40.94%)> Larix principis-rupprechtii (38.69%)> Picea asperata Mast (36.68%)> Betula platyphylla Suk (36.50%)> Populus cathayana Rehd(29.41%). From the overall trend, the canopy interception rate decreases when the rainfall is increasing.(3) The thickness of litter of six different forest is between7-37mm. Mixed forest litter reserves is significantly larger than the pure forest, and coniferous forest is greater than the broad-leaved forest. The litter effective interception of six forest was10.65-86.74t/hm2, equivalent to1.06-8.67mm depth of water, in the order of Picea asperata Mast mixed Betula platyphylla Suk (8.67mm)> Picea asperata Mast mixed Larix principis-rupprechtii (6.94mm)> Picea asperata Mast (6.15mm)> Larix principis-rupprechtii (3.49mm)> Betula platyphylla Suk (1.44mm)> Populus cathayana Rehd (1.06mm). Visiblly, effective rainfall impoundment capacity of litter layer of mixed forest is greater than the pure forest, and coniferous forest is greater than broadleaf forest.(4) It is non capillary water holding capacity and the soil saturated hydraulic conductivity that directly affects the soil water hydrology function. In the six forest, the non capillary water holding capacity of Betula platyphylla Suk (107.40t/hm2) is biggest, followed by Picea asperata Mast mixed Betula platyphylla Suk (87.79t/hm2), Larix principis-rupprechtii (83.75t/hm2), Populus cathayana Rehd (82.32t/hm2), Picea asperata Mast mixed Larix principis-rupprechtii (51.86t/hm2), Picea asperata Mast (26.54t/hm2) is the minimum. The order of the soil saturated hydraulic conductivity is Betula platyphylla Suk (0.87mm/min)> Populus cathayana Rehd (0.80mm/min)> Picea asperata Mast (0.63mm/min)> Picea asperata Mast mixed Larix principis-rupprechtii (0.47mm/min)> Picea asperata Mast mixed Betula platyphylla Suk (0.43mm/min)> Larix principis-rupprechtii (0.33mm/min).(5) The water conservation capacity is significantly different in in different forest. The water conservation function of Picea asperata Mast mixed Betula platyphylla Suk is the strongest, followed by Betula platyphylla Suk, Picea asperata Mast mixed Larix principis-rupprechtii, Picea asperata Mast, and Populus cathayana Rehd, Larix principis-rupprechtii is the worst.