|其他摘要||As one of the important ways for ecological restoration, flooding disturbance could promoted seed germination, maintain high biodiversity and strengthen the stability of plant community. In Tarim River basin, the lack of ecological water is the key limiting factor for eco-environment, and it is not clear that how to utilize the finite ecological water to accomplish flooding which leads to restoring of vegetation. Therefore, based on the fundamental theories and methods, with the opportunity of Ecological Water Conveyance Project (EWCP) conducting in Tarim River, this research sets the impact of flooding disturbance on restoration of desert riparian Populus euphratica forest as the main contents, investigates the response and mechanism of vegetation community succession to different flooding disturbance, studies the suitable flooding disturbance mode and groundwater depth for restoration and protection of main constructive species and makes an eco-rotation flow system, for the purpose of providing theoretical basis and technical support for the comprehensive management of Tarim River basin. The main conclusions are stated as follows:
(1)Flooding disturbance can increase the bio-diversity of plants community. This research shows that Shannon-Weiner index and Margalef index are relatively high under the flooding disturbance mode of “once or twice annually, ten to thirty days every time, speed 25~30 m³/s”, and compared to the non-flooding area, Shannon-Weiner index and Margalef index surpass by 79.15% and 112.20% separately. Fortunately, the suitable flooding disturbance mode for restoration of desert riparian forest is “once or twice annually, ten to thirty days every time, speed 25~30 m³/s”, too.
(2)The tree-ring width index for P. euphratica significantly declines as the groundwater depth increases. The needing minimum groundwater depths of P. euphratica for young trees, near-mature trees, mature trees and over-mature trees are 4.0 m, 5.0~5.4m, 6.9 m and 7.8 m, respectively. In order to protect the desert riparian forest, the actual groundwater depth should be higher than the minimum groundwater depth for each tree growth stage.
(3)The principles of developing eco-rotation flow system are: the flooding period should be during July to September for the purpose of restoring trees and shrubs, while, to restore the herbs, the flooding period should be April and May; the suitable flooding disturbance frequency is twice or three times annually for maintaining the high level of bio-diversity, with 20 to 30 days every time; to accelerate the germination of P. euphratica seeds and meet the water requirement of seedlings, the max interval of flooding is two years, whereas, from the point of P. euphratica forest conservation, the max interval could be prolonged to 3~5 years.
(4)According to the distribution and water requirement mechanism of vegetation in both bank of Tarim River, the eco-rotation flow system is: vegetation distributed within the range of 3 km from the riverway is supported by riverbed leakage, irrigation is not necessary; vegetation in the range of 3 to 20 km from the riverway should be irrigated twice to four times every five years, however, the area where vegetation grow worse and groundwater is deeper should be irrigated three to five times every five years; vegetation distributed beyond the range of 20 km from the riverway should be irrigated once or twice every five years for the lack of water drawn projects.|