Studies On The Vegetation Restoration Mechanism And Ecological Characters In The Key Windy-sandy Region In Beijing

The windy-sandy region in Beijing is an origin of floating dust and sand, and the environmental condition is so bad that there are plenty of troubles in the process of the management and construction. Moisture is the key factor that restrains the recovering and supervision of plant in this area. The investigation obtained abundant data by the methods on -spot outdoors inspection, samples taking, indoor analysis as well as related indexes monitoring and measuring. The thesis focus on four aspects:①reasons of Sandstorm and technical measures on the ecological construction and re-vegetation in the Beijing;②mechanism of re-vegetation and eco-environmental effects in areas covered by artificial plant;③the influences on forest community structure by different re-vegetation models;④the moisture ecosystem and water relation of soil and plant in area covered by artificial plant. The following results are obtained.(1) In the process of recovering and reconstructing vegetation in Beijing, technical measures in certain practical situation take effects. Vegetation arrangement of multi-species, multiplayer and general usage model in sand take full use of the basic environment condition, and take a demonstration for the ecosystem reclamation.(2) The environmental effects on the artificial plants areas are obvious. The microclimate of forest is improved; the surface soil erosion is prevented; the roughness of the earth surface is increased and the nature dustfall is declined; species and quantity of herbaceous plants in the forest are increased. In the process of re-vegetation, the rate of the silt and cosmid is increased, the average volume density is declined, the air amount is increased, the available moisture for plant is increased, the ability for preventing erosion is enhanced.(3)Though the multi-vegetation analysis in the re-vegetation area, two points are get:①the vegetation diversity in artificial forest is almost the same as in natural ones. Although the forestation condition is different in sandstone area and desolate sands, effect by the geographical environment, the dominant plant in herbaceous layer is same, and the constitution of the vegetation community is similar.②the flora of the introduce plant is complex. Although the growing situation is well, further research for the environment adaptability of various species is demanded.(4)In the research of the moisture ecology.①the environmental factor has different degrees of influence on evaporation as the species of trees differ.14 mathematics models on predicting the evaporation velocity are obtained. locity of the tested species, with single crest and double crests and mixed crests respectively.②the transpiration velocity are low in Robinia Pseudoacaia Linn.and Populus alba L.var.pyramidalis Bge,and high in flowering shrub and drought plant.④③the fluctuation of the strength of the regulating ability as well as the anti-drought are different in changing species and weather.(5)In the test areas, the average ratio of water infiltering to soil is most related to proportion of...