Study On Ecology Of Mountain River Habitat

One of the most serious problems in regions with the highly-developed economy over the world is the deterioration of river ecosystem. How to effectively do the management and restoration in order to obtain all the key ecological components, river habitat is an important method. As in river ecosystem, a river habitat integrated extending from headwater to estuary at vertical side, is a horizontal combination of floodplain, channel and water body. The habitat study on Mountain River is not only abundance for optimizing river classification system, but also has an important practical significance and application value to the protection of ecological of river habitat and biodiversity.The paper takes Pengxi River in Kaixian County as an example for study. The classification system of river habitat is built up based on the hierarchy classifying of rivers and streams of Mountain River, which tends to elaborate from the perspectives of morphology and ecology. Meanwhile, it studies on the changes of river habitat under water level fluctuation and ecological effect, probes into the problem of the ecological water requirement. To sum up, all the study is focused on the scope of river ecology. The characteristics of this article are basing on the background knowledge of river ecology, geomorphology, morphology and hydraulics, the application of 3S technology to divide mountain river habitat into different spatial scales, the discussion of the response of vegetation under the water level changes, and the concentration on the emissions of greenhouse gases, which haven't all been reported in the noticed field of ecology aspect of river habitat in the world.The result shows that:(1)With the Strahler method, meanwhile, taking the slope, vegetation construction, combination condition, water channel width in dry season and the ability of river crossing as important indicators to distinguish the river and the stream, a six-order hierarchy is established to classify the river and the stream in the Dong River basin. Having calculated with AcrGIS software, we found that with the increasing order of streams, the quantity and length of streams trend to be decreased; that order 1 has the largest quantity and the longest length; that the lower the stream order is, the higher the elevation is; that the greater the gradient scope is, the better and more stable the vegetation grows.(2) The classification of river is based on the perspective of morphology and ecology. From the point of morphological view, it classifies the physical habitat. Based on the topography condition at different scales, river habitats can be divided into followings: upstream, midstream and downstream habitats in Macro-scale; riparian habitat and river channel habitat respectively divided by the meso-scale. The riparian habitats contain the riparian forest, shrub, grassland, artificial, etc. The river habitats include cascade, riffle, pool, glide, run, backwater, lateral levee lake, floodplain lake, sandbar, etc. Boulder, Cobble, Gravel, Aquatic plants ne and so on, from the micro perspective are classified functionally with the ecological point of view. Based on the substrate type and biological communities, river habitats can be divided into eight types, including emergent macrophyte, submerged macrophyte, rapids rock and so on.(3) As for the study of water level influenced by the impoundment of the Three Gorges Reservoir, soil water content, soil nutrient concentration and distribution of plants are displayed in an obvious grads. The water content and soil nutrient concentration are the highest near the 155-meter height of water level. The vertical distribution of vegetation spatial pattern demonstrates four belts, which respectively include Floodplain annual herb belt, Xanthium sibiricum belt, Paspalum paspaeoides belt and riparian Heights High-grass plants belt. The study shows that the water level change has a significant impact on the methane emission, especially for the deepest surface water. Therefore, there is a distinct domino affect of bionomics.(4)Considering that habitat of Mountain River is seriously affected by the development of hydropower stations, that a large number of isolated reducing water (dehydrated) cross-sections and habitat fragmentation emerge, we must strengthen the management of reservoir operation to maintain the ecological functions of rivers. The ecological water requirement of Dong River is about 166.7 million m3, which takes 5.7% of annual average runoff of the basin. The ecological discharge of each power station is worked out through calculating the ecological water demand of each reducing water (dehydrated) cross-section. Taking into the consideration of the less water input in non-flood season, the 10% of annual average flow rate is adopted as a consult of discharge flow. Whereas the driest monthly mean flow rate in the past 10 years was used as discharge flow at flood period. Meanwhile, because the rundle water and electricity stations are built and managed by different investment, which leads to disadvantages of unified management of zoology discharge, we still need to set up an effective system of supervision for a reasonable management.