The Study On Protective Effects And Structure Of Farmland Shelterbelts Network In XU HUAI Plain Of Jiangsu Province

Under the environment of constructing"green Jiangsu", in order to improve ecosystem environment of the north of Jiangsu province, increase local farmer income, set up the perfect forestry ecosystem and the flourishing forestry industry system,the paper investigated the relationship between protective effects and structure of farmland shelters network in Caoqiao town,Xinyi county and Sanpu town,Tongshan county,and analyzed their shelterbelt structure,shelterbelts network structure and landscape structure.Main conclusion is as follows:1 When other parameters of shelterbelts network are invariable,the protective effects will change obviously with the changing of shelterbelt width and shelterbelt distance.The protective effects of shelterbelts network which shelterbelt width is 18m is more obvious than the shelterbelts network which shelterbelt width is 8m.When shelterbelt width is invariable,the microclimate factors in this area are different with the changing of shelterbelt distance.The increment of rice output in different shelterbelt distance network is in the sequence of 350m>450m>240m>150m>50m.2 In shelterbelts network,there exists close relationship between rice output and microclimate factors. Air temperature and relative humidity have very close negative relationship with rice output,ground surface temperature and light intensity have very close positive relationship with rice output,and also wind has close positive relationship with rice output.3 Based on the calculation and analysis of poplar growth mode(ly=A(1-e ? Kx)B), the paper makes sure that in study area the protective maturity age of shelterbelts is 8 years, the quantitative maturity age and the regeneration age of shelterbelts is 14 years,the type of structure of shelterbelt is porous shelterbelt,the porosity is 0.25—0.30,the permeability is 0.55,the shelterbelt width is 18m, the shelterbelt height is 15m,the density of shelterbelt is 3m×4m,the shape of shelterbelt cross section is rectangle,the alignment of shelterbelt is north and distance between shelterbelt is 200—400m.4 Comparison between reasonable and existent landscape index of shelterbelts network in Caoqiao town,Xinyi county and Sanpu town,Tongshan county shows that the area of farmland shelterbelts network in Caoqiao town,Xinyi county is shortage,the amount of shelterbelts is unreasonable and the networks are in bad shape condition,but the arrangement of shelterbelts is reasonable;the structure of farmland shelterbelts network in Sanpu town,Tongshan is unreasonable,shelterbelt width is too small, and the networks are in bad shape condition,but the amount and arrangement of shelterbelts is reasonable.5 In the farmland,it is beneficial to improve landscape diversity and eveness and to provide more kind of ecological environments for biology that the area of shelterbelts network increase at certain range.6 The main management of farmland shelterbelts network in Caoqiao town,Xinyi county is constructing the farmland shelterbelts system and improving the landscape index of shelterbelt networks such as connectivity,ring,landscape diversity and eveness by planting new shelterbelts to increase the area of shelterbelts network step by step. The main management of farmland shelterbelts network in Sanpu town,Tongshan county is regenerating the shelterbelt by planting tree and adjusting the ratio of belt to patch,ring tend to be reasonable by planting new shelterbelts.