Study On The Preferential Flow Of Four Kinds Of Forest Stands Soil In Nanjing Purple Mountain

This study to the Nanjing Purple Mountain four kinds of forest stands soil as the research object,through dyeing tracer method to study the regional preferential flow occurs,photographing dyed profile Image,Image through Adobe PHotoshopCS5 illumination correction,the use of Image ProPlus6.0 to extraction and analysis of the illumination corrected Image,the morphological characteristics of preferential paths,the change characteristics of dyed area ratio,the characteristics of dyed paths change,the classification of preferential flow and the analysis of dyed index are studied.By measuring the gravel content,soil physical and chemical properties and plant roots of the dyed and non-dyed areas,the factors affecting the preferential paths are studied.The conclusions are as follows:(1)In the horizontal section dyeing of four kinds of forest stands,the soil solute transfer was obviously.The change of the dyed area of the Quercus acutissima forest stand,Liquidambar formosana forest stand,and Pinus massoniana forest stand was significantly different,the dyed depth reached 40 cm,the change of the dyed area of the Phyllostachys pubescens forest stand was very significant,and the dyed depth was 30 cm.Dense areas of dyed areas also have many preferential paths.The area of preferential paths will deepen the dyed depth.In the vertical flow dyed images,the preferential flow of Quercus acutissima forest stand was the most frequent in four kinds of forest stands.The soil preferential paths of Liquidambar formosana forest stand showed a significant fingerlike dyed paths.Pinus massoniana forest stand preferential flow activity is stable.The soil percolation of Phyllostachys pubescens forest stand and Pinus massoniana forest stand took place.The dyed area ratio of Phyllostachys pubescens forest stand is fluctuant and the priority flow activity is frequent.(2)There are some differences in the distribution of dyed paths at different widths.The dyed paths smaller than 20 mm and greater than 200 mm is different peak in different soil layers.With the increase of soil depth,the peak value of dyed paths decreases with increasing soil depth.The dyed paths with a width of less than 20 mm is good continuity,and is the main paths of water flow and the main paths of preferential flow.The dyed paths with a width greater than200 mm has obvious discontinuity,and its distribution is mainly on the surface of the soil,which is related to the occurrence of soil matrix flow.The difference of soil preferential flow types between the four kind of forest stands is quite different.The surface soil of the Quercus acutissima forest stand is mainly "homogeneous matrix flow,non homogeneous matrix flow "and "homogeneous matrix flow" "These two types of preferential flow.The preferential flow of Liquidambar formosana forest stand is different,and preferential flow is obvious.The surfacesoil preferential flow types of Pinus massoniana forest stand and Phyllostachys pubescens forest stand are very stable,which are "homogeneous matrix flow ".Based on the analysis of four dyed diagram parameters,it can be concluded that the preferential flow of Liquidambar formosana forest stand is the best and that of Quercus acutissima forest stand is the second,and that of Pinus massoniana forest stand and Phyllostachys pubescens forest stand the worst.(3)Soil preferential flow in different forest stands was affected by soil physical and chemical properties,gravel content and plant root condition.Soil physical and chemical properties,gravel content and plant root condition all showed significant correlation in dyed area and non-dyed area,and some properties were significantly correlated.By the principal component analysis,it is concluded that the size and contribution rate of the comprehensive load value 8 factors from large to small as follows: sand content,less than 1mm root length density,root weight density,gravel content,1-3mm root length density,3-5mm root length density,greater than 5mm root length density,soil bulk density..However,the three factors,such as silt content,clay content and organic matter content,have little effect on the preferential paths.