| In recent years, ecological problems such as the shortage of water and vegetation degeneration occurred in the Li River, which has become a serious challenge to sustainable development for eco-tourism of Li River, and vegetation restoration is urgently needed. In this paper, we studied the spatial distribution of vegetation and soil in different inundation zone of aquatic-terrestrial ecotones in Li River, research on the response mechanism of vegetation, soil and hydrology, and analysised vegetation impact factors of focus revegetation area, explored vegetation configuration mode of the degraded ecosystem in aquatic-terrestrial ecotone, that aims to provide a scientific basis to vegetation restoration, landscaping, wetland protection and management and its sustainable use in aquatic-terrestrial ecotones of the Li River.The preliminary research results are as follows:(1) Preferred hydrological effect, relative elevation, slope, gravel content and vegetation biomass as the partitioning index, according to the regression equation and principal component analysis, we choose flood time, relative height and biomass as a leading indicator. Through clustering analysis, we divided aquatic-terrestrial ecotones into four inundation zone, such as, severe degree inundation zone, middle degree inundation zone, light degree inundation zone, and micro degree inundation zone.(2) Species composition of aquatic-terrestrial ecotones were relatively abundant, and there were124species of plants, including18species of arbor plants,17species of shrub plants,89species of herbaceous plants, that species composition were relatively abundant. With the increase of riverbank elevation, diversity trend, evenness, dominance, coverage and biomass presented an increasing trend, the number of species had become increasingly diverse, and species composition structure had become complicated.The vertical distribution of diversity, evenness, dominance and coverage along the river had obvious difference, evenness index showed same law with the diversity index basically, on the contrary, dominance index presented opposite withdiversity index and evenness index, vegetation biomass present a tendency of increase from upstream to downstream.(3) The soil physical characteristics in different inundation zone were obvious different, with the increase of riverbank elevation, Soil bulk density increased initially and then decreased. Sand content declined significantly. Silt and clay content increased significantly, Sand content was much higher than silt and clay content, which was related to the improvement effect of vegetation. Soil organic matter decreased initially and then increased. Total nitrogen content continuously increased, the content was form0.399g/kg to0.556g/kg. Available phosphorus content presented a reducing trend that was unnatural, related to non-point source pollution on the shore of Li River. Total potassium content was not significant difference in different inundation zone. The soil pH value was between7.124and7.868, and the alkaline soil pH of Karst ecotone was negatively correlated with total nitrogen content while it was positive correlated with available phosphorus content. Soil properties influence vegetation diversity. The results showed that vegetation diversity trend, evenness, dominance biomass and coverage were positively correlated with the content of silt, clay, total nitrogen and soil organic matter, but negatively with sand content, soil bulk density, soil pH and available phosphorus content. Furthermore, the results demonstrated that the total nitrogen content was one soil factor that had the largest influence on vegetation growth.(4) Under the influence of the hydrological effect, annual herb species occupied the absolute superiority in herbaceous community of aquatic-terrestrial ecotone. After a hydrological cycle, vegetation type and vegetation diversity index showed a trend of decline in all of inundation zone. Soil sand content increased, but silt and clay content showed a trend of decline. The soil bulk density showed a trend of rising, soil pH, organic matter, total nitrogen, total phosphorus and total potassium content showed a trend of decline.(5) We choose severe degree inundation zone and middle degree inundation zone as the key area of vegetation restoration, in this area, space correlation of herbaceous vegetation were negative related with human disturbance intensity. The results showed that the distribution of vegetation index had obvious spatial structure in the three study area, and were in accordance with different variation function theory model. Vegetation index of city tourism type had a moderate spatial correlation, except for evenness index of Weijiadu, the vegetation index of Suburban life type and natural type has a strong spatial correlation.Vgetation indexes of herbaceous vegetation had a close relationship with structure factors, human disturbance intensity. Vegetation index of urban tourism type presented a distribution of middle small and large of both sides. The spatial distribution of vegetation index were different in three study area. Vegetation indicators of suburban life type showed a banded distribution, but in high value distribution band, there were many low areas Vegetation indicators of natural type showed a banded distribution from west to east. The natural structure factors had significant effects on the spatial variability, while human disturbance played a secondary role, and the effects of random factors were relatively low.(6) Based on three different intensity of human disturbance of aquatic-terrestrial ecotone in Li River, such as Lijiangqiao, Weijiadu and Qianjingcun, vegetation configuration of urban tourism type (With a strong degree of human disturbance) will focus on landscape, vegetation configuration of suburban life type (Medium artificial disturbance) will focus on ecological value and economic value, and aquatic-terrestrial ecotone for natural type (Little human interference) will pay attention to the naturalness. |
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