| Nitrogen fixing plants can improve soil texture and fertility,conserve soil and water and improve the ecological environment;also they have the characteristics of strong resistance,fast growth,good ecological benefits and high landscape value.Therefore,they are valuable to the production of agriculture and forestry;also they have a high aesthetic value in plant landscape.Research on the application of nitrogen fixation plants is significant to the beautification and improvement of environment and to the improvement of ecological benefits of garden green space.Through field investigation and research,the author learnt about the present situation of the application of nitrogen fixation plants in Nanning urban garden green space,which will provide important reference for future soil improvement,soil fertility improvement and improvement of environment in Nanning.This would help to provide not only basis for the selection of good nitrogen fixation plants for Nanning urban landscape construction,but also a reference for the future growth and cultivation of nitrogen fixation plants.The author study and analyze the resources of nitrogen fixation plants and the current situation of its application through literature collection,field investigation and questionnaire survey by means of statistical analysis and analytic hierarchy process.The main research results are as follows:(1)only a small amount of species are widely planted.Through research,the author find that there are 133 kinds of nitrogen fixation plants in Nanning,and only about 50 kinds of species are commonly used,among which there are 40 kinds of leguminous plants and 10 species of non leguminous plants.Cycas revolute,Calliandra haematocephala,Acacia confusa,Podocarpus macrophyllus and some other few species are widely used in gardening.(2)Environmental adaptability is strong.Through the analysis of nitrogen fixation plants,planting sites,the author find that nitrogen fixation plants are well grown in comprehensive parks,special parks,ribbon parks,residential green spaces,public facilities green spaces,road green spaces,municipal facilities green spaces and other green spaces.These nitrogen fixation plants mainly include Leucaena leucocephala,Cycas revoluta,Calliandra haematocephala,Acacia confusa,Alysicarpus vaginalis,Kummerowia striata,Pueraria lobata,etc.(3)Forms of planting are various.Through the analysis of the planting pattern of nitrogen fixation plants,the author comes up with a conclusion that nitrogen fixation plants planted in a variety of forms,which can be isolated planting,group planting,row planting,group planting,scattered planting,three-dimensional green vegetation,Hedgerow planting,and form a beautiful landscape together with building,King Stone,garden sketches,garden structures,.etc.(4)Landscape values vary widely.The comprehensive value of nitrogen fixation plants was evaluated by AHP,and the comprehensive weight values were compared:aesthetic function(0.33885)>growth performance(0.2881)>ecological function(0.2401)>resource value(0.0832).A conclusion can be drawn from the weight value that aesthetic function is the most important index,followed by growth performance.After evaluating the total score of the 50 kinds of nitrogen fixation plants,the final comprehensive score was found to ranged from 2.7181 to 3.3670.The results showed that there were five types of grade I,17 species of grade II,13 species of grade ?,6 species of grade IV and 19 species of grade V.(5)Both planted species and widely planted species are less.Nitrogen fixation plants that are fond of sunlight were planted in the shade environment without considering their ecological habits.The slow-growing nitrogen fixation plants were planted in fast-growing plants. |
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