Study On Para Allocation Of Protection Forest System In Typical Watershed Of Beijing Mountain Area

Less water resource, serious soil erosion and strong sandstorm are concentrated experience of worsens ecological environment of Beijing, and puzzled ecological construction of capital. Beijing mountain area is an important ecological barrier of Beijing city, which plays influential role on maintain soil and water, conserve water resource, protection sandstorm and improvement environment. But unreasonable spatial allocation and structure, weakened ecological function, incompatible protection forest systems'scale with ecological water use and quota of ecological water use serious hindered ecological function of protection forest system in Beijing mountain area. In order to optimize structure and enhance function of protection forest system, the research start with structure pattern, structure allocation and relation of water and soil, pare allocated protection forest system, analysis relation of water and soil resource with protection forest system, proposed para allocation patterns of protection forest system in typical watershed. The main research results are as follows:(1) Start from forest resource situation of Beijing mountain area, take the villages and towns or the farm as research unit, divided protection forest system of Beijing mountain area into five types by using factorial analysis and cluster analysis method, propose suitable forest type of each protection forest system.(2) Concerning of main ecological oriental of typical watershed, collected land use, rainfall, water quality data. Discussed computational method of suitable forest coverage in typical watershed, and thought retain maximum rainfall, reduce soil erosion and purify water should be concerned. The result shows: suitable forest coverage rate of Tumen West watershed is 54.94%, suitable forest coverage rate of Chaoguan West watershed is 55.36%, suitable forest coverage rate of Banchengzi reservoir watershed is 58.61%. The result offers reference on protection forest system construction in small watershed.(3) As a foundation of research on forest characteristics, take"near natural forestry" as rationale, used systems dynamics model artificial neural network to allocate forest type, the disposition results show: coniferous forest 13.40%, foliage forest 30.24%, mixed forest 34.99%, scrub forest 21.37% in Tumen west watershed; coniferous forest 3.66%, foliage forest 19.36%, mixed forest 52.45%, scrub forest 22.65% in Chaoguan west watershed; coniferous forest 22.71% hm2, foliage forest 8.72%, mixed forest 37.78%, scrub forest 29.24% in Banchengzi reservoir watershed.(4) Choose dominant species Pinus tabulaeformis, Platycladus orientalis, Robinia pseudoacacia, Quercus, Vitex negundo, Spiraea, Carpinus turczaninowii Hance as object in Beijing mountain area, research influence of slope, elevation, soil type, soil texture on their high growth and diameter growth, provided reference for site selection and protection forest system's construction. Analyzed interception capacity of forest crown, litter and soil, and the conclusion indicated the strongest is mixed forest.(5) Used GIS, RS and FRAGSTATS to research landscape patterns and driving of Banchengzi reservoir watershed from 1990 to 2005, and construct spatial data and attribute data in SWAT. According to DEM, Banchengzi reservoir watershed is divided into 23 sub basins, and calibrated parameter with hydrology data from 1990 to 2006, the model shows: rainfall characteristic and land use characteristic strong influenced runoff. With plenty rainfall, the runoff is bigger; with less rainfall, runoff is small. Disposition result of protection forest system shows: runoff of foliage forest, coniferous forest, scrub forest and mixed forest are 122.26mm, 185.34mm, 340.18mm and 255.33mm. Ecological water use of forest is reduces, the amount of runoff increases 490,100m3. The results provided effective method to research the relation of landscape and hydrology response.