Studies On Formation Mechanism Of 'Black Soil Type' Degraded Grassland And Restoring Pattern In The Source Region Of Yangtze, Yellow And Lantsang Rivers

In view of the present situation on the serious degradation alpine meadow in the source region of Yangtze,Yellow and Lantsang Rivers, through years of field investigation and studies, we divided the alpine meadow into undergraded grassland, light degraded grasslands, medium degraded grassland, heavy degraded grassland and extreme ('black soil type') degraded grassland that five degradation succession processes, and communities composition, degradation causes and succession rules on each stage were studied in detail. Then, using the principles of the restoration of ecology, proposed the alpine meadow degradation ecosystem restoration and reconstruction pattern in the source region of three rivers. The systematic study focus on the restoration and alteration patterns and mechanisms of'black soil type'degraded pasture vegetation, and there are several important results for restoring'black soil type'degraded pasture and developing stockbreeding in the region.The area of grassland in the source area of three rivers is over 85% of total land area, alpine meadow is the main body in the alpine ecosystems. The area is facing the problems which is the largest, the most extensive coverage, and the consequences of the most serious of ecological environmental degradation throughout history, mainly for pasture serious degradation. According to statistics, the areas of the medium degraded grassland is10 million hm~2, accounting for 63.3% of the total region grassland, the heavy degraded grassland and extreme ('black soil type') degraded grassland is around 3.3 million hm~2, accounting for 1/3 areas of the medium degraded grassland total area . The production of such pasture is account for only 13% of the undergraded grassland, with an average coverage of vegetation for 45% .In the composition of plant species, 60% to 80% are the broad-leaf Poisonous Weeds on the degradation grassland, it has largely lost ecological and livestock value.The several stages of the degradation in the source region of three rivers alpine meadow are undegraded grassland-light degraded grasslands-medium degraded grassland-heavy degraded grassland - extreme degraded grassland. And the vegetation community composition and succession rule is that: The stage of sedges vegetation community-the stage of sedges and grasses vegetation community-the stage of grasses and sedges and forbs vegetation community-the stage of forbs vegetation community-the stage of annual forbs...