The Research On The Eclogical Benefit Of Riparian Buffer Strips

Riparian buffer zone is a new area to the other ecosystem. There are many ecological and environmental problems in China, such as shorting of water, water pollution, sharp reducing of species and so on, so it's quite significative to research the management of riparian buffer strips. Factually, riparian zone are useful to control the water pollution and eutrophied waters, protect the safety of source of drinking water, enhance slope stability, keep soil and water conservation of stream bank. The application of riparian buffers has a good effect on improving the environment of habitat and offering channels for animals. Riparian buffer strips has great prospect in the ecological management of China's rivers, but also there are many issues to be resolved. Domestic research on riparian buffer strips is mainly in source pollution controlling and landscape features, but lacking of systematic research on the other eco-efficiency. Biologic habitat, soil and water conservation, improvement of habitats subjects to great restrictions.The sampling sites chosen for this thesis is the riparian buffer strips in Dongfeng river. Biological assessment is used to research the function of improving the biologic diversity. From autumn in 2006 to winter in 2007, we investigated the riparian buffer strips five times, including detailed investigation on the community structure of plant, soil animals, plankton, and zoo benthos. Temperature, humidity, structure of soil, physical and chemical factors of soil is detailed analyzed too, in order to find out the relationship between the environmental factors and the biologic community. From the research of shear strength of soil, soil compaction values, biomass of some plants, and the main three grasses' reducing efficiency of SS in runoff, to find out the riparian buffer strips' efficiency of the slope stability. The main findings are as follows:1. Riparian buffer strips of Dongfeng river improves the quality of habitatsThe plants of the riparian influence the local microclimate, and improve the quality of habitats. It's obvious that the plants improve the humidity and reduce the temperature of the soil. In summer, the temperature reducing is visible while in autumn and in winter the humidity increasing is obviously.In addition, it's clear that when plants develop better, the temperature reducing and the humidity increasing are more obvious. Soil with great plant in has higher humidity and lower temperature in each season. In other words, status of plant and the covering area of it are related to the adjusting ability of microclimate.2. Riparian buffer strips of Dongfeng rive improves diversity of biologic communityThe riparian buffer zone allocates reasonably of the trees, shrubs, grass and other vegetation, more than 30 species of plants provides habitat with more biological diversity, and has a good sense of visual beauty. Soil animal biodiversity, it's far higher in the demonstration zone than other plots like wasteland and so on. Correlation analysis found that total nitrogen content in soil and the soil animals' numbers was significantly correlated; potassium content of the soil is very significant negative correlation with the soil animals' numbers and negatively correlation with the density of soil animals. Other factors on the impaction of soil animals are not visible.Demonstration Area waters with a more complete ecosystem and food chain, such as a more abundant aquatic vegetation, including Scirpus tabernaemontani (S.validus), Iris pseudacorus, Nymphaea tetragona, Ceratophyllum demersum, Lemnaceae and so on, making the area has more complex habitats for the animal, and biological Diversity is higher. The control area of scarce water plants, a single habitat, biodiversity will correspondingly lower. The density and biodiversity of phytoplankton and zoo benthos are better in demonstration area waters than the control area, and dominant species in demonstration area are more adjacent to clean water species. Water quality in Dongfeng river trends to be better.3. Riparian buffer strips of Dongfeng rive enhances the stability of stream bankFibrous root growth of vegetation developed shear strength of the soil layer significantly enhanced. When vegetations of buffer zone are different kind, root depths are different, that shear strength of the soil is different, and to the maximum depth of different layers of soil, soil erosion capacities are also different. In the same slope, Trifolium repens and Cynodon Dactylon L.Pers can be effectively suspended the interception of runoff and improve shore slope of anti-erosion ability, while Festuca arundinacea has poor performance, this point needs further research. When slopes are Different, greater the slope is, more unsatisfactory result is.Comparing with the three species of grasses, they have different abilities in withstanding soil-erosion and strengthen the stability of slope. Although the roots of Festuca arundinacea are numerous, but the test results were not satisfactory. Trifolium repens is more nice-looking, and the improvement of shear strength of the soil is also obvious, but Alternanthera philoxeroides(Mart.)Griseb will occupy the plots if Trifolium repens have improper maintenance in summer, so that it's impaction on soil and water conservation Effect will be limited. Cynodon Dactylon L.Pers develop strong, especially in high temperature. In summer, the roots growth is particularly rapid, forming a very developed mesh-ground, so that it is suitable for the Soil and Water Conservation.At present there are still some problems need to study and be solved, and area of the research is not wide enough .A great deal of work needs to be done, to Provide experience and learn from of the buffer zone research for similar areas in Shanghai and other regions of China.