The Promoting Effect Of Soil And Vegetation Recovery Between Low Coverage Sand-fixing Forest Belts

Low coverage sand-fixing forest of belt scheme is afforestation of trees and shrubs in one line or multiple lines, and the belt is the space between multiple lines or vegetation restoration belt. The belt scheme forest is a complex combination of vegetation pattern, which alternate with the narrow forest belt (covers an area of 15%-25%) and wide natural vegetation restoration belt (covers an area of 75%-85%). An ecological interface of forest and grass will be formed between the narrow forest belt and the vegetation restoration belt, that is forest and grass interface, this interface has significant ecological effect, to promote the interval vegetation recovery.The characteristics of community and structure, the physical and chemical characteristics of soil, the amount of microbes of soil in the low coverage sand-fixing forest with different distance between belts under the different recovery scale were investigated in 2009 and 2010. The data obtained from the experiment were analyzed with the principal components, the canonical correlation and fuzzy comprehensive evaluation method, which obtain coefficient of different recovery scale. The ecological effects of boundary between forest and grassland were analyzed, and the effects of Landscape boundary on vegetation restoration were clarified to disclose the suitable distance between sand-fixing forest belts. The results were shown as follows:1. Belt scheme of sand-fixing forest could improve the interband vegetation and soil rehabilitation effectively; vegetation and soil rehabilitation depend on distance between neighboring belts. Suitable distance between the belts will rehabilitate significantly.2. In different research area, the silt and clay of soil significantly increased in the wide spacing forest; the soil coarse particle and bulk density were significantly decreased, soil moisture content was significantly increased; the soil nutrient content were significantly higher in wide distance between the belts than in narrow distance between the belts, and the pH of wide distance between the belts is more closer to the zonal soil.3. The total number of microorganisms was significantly higher in wide distance between the belts than in narrow distance between the belts, The bacteria number between the belts of 18m interval,6m interval and random Caragana korshinskili forest were current control 1.05,0.80 and 0.75. The bacteria number between the belts of 20m interval,15m interval and 10m interval Populus chifengensis No.36 forest were current control 0.76,0.52 and 0.48. The bacteria number of Pinus sylvestris forest between the belts of 24m interval and12m interval were current control 0.47and 0.34.4. In different research area, when the distance between the belts increased, the composition of community species was gradually complex, quantity increased, the important value of species and the composition of Family-Genus varied obviously, and the perennial plants gradually increased with grassland recovery. The index of diversity and above-ground biomass of community increased gradually, and the similarity coefficient of community in the different recovery scale was a rising trend with grassland recovery. The Caragana korshinskili forest belts of 18m interval and 6m interval reached 0.833 and 0.650 of the similarity coefficient for the control community; the Populus chifengensis No.36 forest belts of 20m interval,15m interval and 6m interval reached 0.769,0.588 and 0.485 of the similarity coefficient for the control community; the Pinus sylvestris forest belts of 24m interval and 12m interval reached 0.654 and 0.609 of the similarity coefficient for the control community.5. In different research areas, the variation trend of root biomass, total length and surface area showed: the Caragana korshinskili forest was 18m>6m; the Populus chifengensis No.36 forest was 20m>15m>10m; the Pinus sylvestris forest was 24m>12m. Band spacing is too small will affect the root growth of vegetation.6. The boundary effect area of Caragana korshinskili forest belts is no more than 20m, and the distance of forest belts should with appropriate spacing 12-28m; the boundary effect area of Populus chifengensis No.36 forest belts is no more than 18m, and the distance of forest belts should with appropriate spacing 20-36m; the boundary effect area of Pinus sylvestris forest belts is no more than 20m, and the distance of forest belts should with appropriate spacing 16-40m; otherwise the forest belts could not promote the vegetation recover.7. According to the fuzzy comprehensive evaluation of vegetation and soil, The vegetation and soil restoration scale between the belts of 18m interval,6m interval and random Caragana korshinskili forest were current control 75.78%,62.39% and53.54%; the vegetation and soil restoration scale between the belts of 20m interval,15m interval and 10m interval Populus chifengensis No.36 forest were current control 68.63%,55.01% and 42.04%; the vegetation and soil restoration scale between the belts of 24m interval and 10m interval Pinus sylvestris forest were current control 61.79% and 50.18%.