Analyze About The Wind-break Potency Of Sympodial Bamboo Under Different Spatial Structure In The Coastal Sandy Area

Five kinds of sympodial bamboos include Dendrocalamopsis oldhami,Dendrocalamus latiflorus,D.beecheyana var.pubescens,Bambusa vulgaris,Dendrocalamus minor var.amoenus is the object of this research which had already planted in ChiShan forest farm in DongShan Island,Fujian province.Make a comprehensive analysis and evaluation of the bamboo's wind break efficiency by use AHP from forest stand characteristics,forest stand structure and mixed patterns.The purpose of this study is to provide theoretical foundation and reference basis for scientific management and breeding of coastal sand bamboo protective forest The main results include:1.Shelterbelt porosity is a important measurement index of stand structure.The wind-break efficiency of Dendrocalamopsis oldhami under sparse structure is the best,it was 10.91%,4.84%,12.73%and 4.26%higher than Dendrocalamus latiflorus,D.beecheyana var.pubescens,Bambusa vulgaris and Dendrocalamus minor var.amoenusthe respectively.Under the ventilation structure,the average wind break efficiency of D.beecheyana var.Pubescens,Dendrocalamopsis oldhami and Dendrocalamus latiflorus is better than the others,and the wind break efficiency is more than 26%.Under the tight structure the average wind break efficiency of Dendrocalamopsis oldhami and Dendrocalamus minor var.Amoenus is the best,the wind-break efficiency is 37.68%and 27.63%respectively.2.The wind-break efficiency of 5 coastal area sympodial bamboos will approve while the stand density is arise.Choose 5 sympodial bamboos which were planted in Chishan forestry centre for 2 years.Under the stand density of 800 plant per hectare,the average wind-break efficiency after 5 coastal area sympodial bamboos is 24.82%.The wind-break efficiency of Bambusa vulgaris is 29.1%which is the best.Under the stand density of 2100 plant per hectare,the average wind-break efficiency of Dendrocalamus latiflorus is 63.4%which has the best.Under the influence of shelterbelt porosity,the wind break efficiency improve ratio will slowly down when the stand density is range is added.3.The wind break efficiency of sympodial bamboo forest will enhance at first then reduce slowly when the wind speed is rise.The trend of wind speed in the forest belt of five sympodial bamboo forests is consistent.The wind speed will decrease slowly between 1H and 3H,and lowest at distance of 3H,descend to 52.8%-69.1%.The wind break-efficiency of 5 sympodial bamboos forest from high to low is Dendrocalamus latiflorus(54.29%)>Dendrocalamopsis oldhami(48.39%)>D.beecheyana var.Pubescens(44.27%)>Dendrocalamus minor var.Amoenus(33.54%)>Bambusa vulgaris(30.79%).4.The breadth of shelter belt and the distance between shelter belt can influence the wind-break efficiency of sympodial bamboo forest from spatial arrangement.The wind break efficiency will arise when the breadth of shelter belt is added,and the lowest wind speed appear at the distance of 3H-4H after shelter belt.The accumulate wind break efficiency will decrease when the distance between shelter belt is added.5.The wind break efficiency will decrease when the height and wind speed added at different distance after shelter belt.The wind break efficiency of different shelterbelt porosity at 3 height is:sparse structure 39.3%>tight structure 39.0%>ventilation structure 32.6%.6.The bamboo forest mixed with Casuarina has better wind break efficiency than pure Casuarina forest.The wind break efficiency of forest mixed by individual tree at the proportion of 2:1 is:D.beecheyana var.pubescens 53.70%>Dendrocalamopsis.oldhami 48.21%>Dendrocalamus latiflorus 42.86%>D.minor var amoenus 41.18%>Bambusa vulgaris 38.46%.The wind break efficiency of forest mixed by band at the proportion of 5:3 is:D.beecheyana var.pubescens 64.50%>Dendrocalamopsis.oldhami 62.70%>D.minor var.amoenus 56.30%>D.latiflorus 55.20%>Bambusa vulgaris 52.00%.The wind break efficiency of forest mixed by block at the side length of 10-15mis:D.beecheyana var.pubescens55.41%>Dendrocalamopsis oldhami 45.31%>D.minor var amoenus 44.00%>Dendrocalamus latiflorus Munro 42.37%>Bambusa vulgaris 40.58%.7.Build a comprehensive analysis and evaluation model for the wind break efficiency of 5 ways to mix coastal area bamboo with Casuarina.And the value of comprehensive analysis and evaluation is:mixed by individual 41.14%>mixed by block 36.82%>mixed by line 19.25%>mixed by banded 18.88%>mixed by star 12.36%...