| Originated in DaBan Mountains, Baoku river is the secondary tributary of the Beichuan river, which is the supply river of the famous Heiquan reservoir. Heiquan reservoir plays an important role in the water supply of Xining which is the capital city of Qinghai province. Heiquan reservoir accounts for60%.of all the water supply for Xining. Thus we can see its importance in terms of water supply. There for maintain the water supply of Xining focus on the artificial forest plantation which has function of water adjustment, water quality improvement and the control of soil erosion. This article based on the "12th five-year "science and technology research project. To treasure of river basin, the main plantation tree species characteristic carries on the comprehensive evaluation of water conservation. The research purpose of this paper is mainly to chase will provide a scientific basis for construction of water conservation forests in qinghai region, and will help determine the development direction of forestry ecological engineering construction in the region. The main results were as follows:(1) The study area in different forest types of artificial undergrowth shrub layer species abundance index according to the needle leaf mixed forest, coniferous forest, broad-leaved forest in the order is reduced, the herb layer species richness index also showed the same change trend; In vertical space level, most types of artificial forests herb layer richness index and diversity index were higher than the shrub layer, fully embodies the treasure river basin in the existing artificial undergrowth is given priority to with herbs, shrubs, plants are relatively rare appearance, herb layer to a great extent, determines the undergrowth species richness in the region.(2) Vertically, interception by different configuration of the plantation community ranks as:tree layer, shrub layer, herbaceous layer (in descending order). The average interception of tree layer, shrub layer, and herb layer is7.50mm,2.09mm, and1.42mm, respectively accounted for68.1%,19.0%, and12.9%of the entire community vegetation canopy interception; types of forest vegetation interception is higher compared with local advantageous crop canopy, but the interception differs among configurations of different tree species. Qinghai spruce, the local zonal climax community has the highest interception, followed by spruce birch forest, larch, spruce and larch mixed woods, and pure birch forest; among the vertical sequence, vegetation canopy interception ranks lowest, average of only2.20mm (1.26-2.66mm), but the main role of the canopy is to reduce precipitation erosion hazards, so as to achieve soil and water conservation.(3) The litter volume of five different forest types of the study area is between30.2to73.2t/hm2, average maximum water holding capacity is between98.05～167.42t/hm2, coniferous and broad-leaved mixed forest has better water-holding ability than the broad-leaved forest, and the broad-leaved forest is better than coniferous forest; the water holding capacity and soaking time of litter can be calculated with the formula W=aln(t)+b, and water absorption rate and soaking time of litter can be fitted with formula V=ktn, in which t is the soaking time.(4) Soil bulk density overall is not very different among forest types, but is lower than that of farmland, meaning the forest land has improved soil permeability and water holding capacity. Effective water holding capacity of different stands ranges between15.73～32.24t· hm-2. By comparing water holding capacity, effective water quantity and water holding capacity, it is shown that spruce birch mixed forest and spruce and larch mixed forests have the best water conservation capacity, and spruce plantation has the worst, requiring improvement of forest structure.(5) The configuration of various species plantations showed significant differences in water conservation capacity, for the comprehensive evaluation value was between-1.328to1.575among15plots. From different forest types, the overall situation in descending order were spruce birch forest> spruce and larch mixed> pure spruce forest> pure North China larch white birch forest. |
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