Study On Properties And Health Assessment Of Soils For Different Forest Vegetation Types In Lushan

Forest soil properties,a key ecological factor to control vegetation growth and development,not only determine the soil quality and health,but also have a crucial effect on soil carbon sequestration.Lushan is located in the eastern part of China's eastern subtropical monsoon climate region,it has special geographical environment and obvious mountain climate characteristics.Due to different climate zones,vegetation types and soil interactions,Lushan has different soil properties and carbon accumulation from the foothills to the top of the mountain.Therefore,studying the soil physical properties and the characteristics of organic carbon pool in different forest types at different altitudes,has important significance to master the health status and carbon budget of forest soils in Lushan.This study selected 8 forest vegetation types which are different typical altitude in Lushan as the research objects: evergreen broad-leaved forest,deciduous broad-leaved forest,mixed evergreen and deciduous broadleaved forest,Masson pine forest,Pinus taiwanensis forest,mixed wood,bamboo forest and shrub.This thesis systemically analyzed properties of soils for different vegetation types such as physical properties,chemical properties,biological properties and variation characteristics of organic carbon pool.Based on the forest soil health index(FSHI)and soil carbon pool management index(CPMI),the soil health status and soil organic carbon pool status of typical forest stands in Lushan were quantitatively evaluated.The main results are summarized as follows:(1)According to the different forest soils physical properties,the litter layer thickness of the 8 types of forest stands is in good condition;The thickness of soil humus under the deciduous broad-leaved forest is the highest and that under Masson pine forest is the lowest,and the thickness of humus layer increase with altitude;The average soil bulk density of the soil under Masson pine forest is smallest and the mean soil clay content of the soil under that is the largest,but for Pinus taiwanensis forest,this situation is just on the contrary.The soil infiltration characteristic and water holding capacity of the soil under Masson pine forest have the best performance,however the mixed evergreen and deciduous broadleaved forest are the worst in that way;The value of soil water storage under Masson pine forest is the largest and that under shrub is the smallest;The results show that the soil of Pinus massoniana forest is relatively loose,with good ventilation,good infiltration and water holding capacity.(2)According to the different forest soils chemical properties,all the 8 types of soil stands was acidic,and the soil acidity of bamboo forest and evergreen broad-leaved forest is larger than that of other forest soils;The contents of soil organic matter,total N,hydrolysable N,total P,available P and CEC in the soil under deciduous broad-leaved forest are the largest,and the average contents of total K and rapidly available K in the soil under evergreen broad-leaved forest are the largest.The contents of soil organic matter,total N,hydrolyzable N,total P,available P and rapidly available K in the 8 types of forest stand are significantly decreased with the increase of soil depth,while the pH value,total K and CEC content changed little with the depth of soil layer.For the comprehensive evaluation of soil nutrient status,the soil fertility level is the largest in deciduous broad-leaved forest and the smallest in Pinus taiwanensis forest.(3)According to the different soil environmental with the different forest soil biological properties,soil cellulase,urease,catalase,polyphenol oxidase and acid phosphatase activity value of the largest forest types were bamboo forest,shrub,evergreen and deciduous broad-leaved forest,evergreen broad-leaved forest and bamboo forest.And the soil enzyme activity decreased with the increase of the soil layer,which has an important effect on the biochemical processes of different forest types.MBC,MBN and MBP showed different differences in different woodlands: the mean of MBC,MBN and MBP in the soil under evergreen broad-leaved forest and evergreen and deciduous broadleaved mixed forest are the largest,and that under shrub is the smallest.MBC,MBN and MBP decreased significantly with soil depth increasing.The diversity analysis of forest vegetation showed that the(R+H)/2 herb layer is higher in shrub layer and mixed coniferous forest under evergreen deciduous broad-leaved mixed forest.The diversity analysis of soil microbial community showed that deciduous broad-leaved forest,mixed conifer forest and Pinus taiwanensis forest are slightly smaller than other forest types.And the species richness of Pinus taiwanensis forest in the 0~40cm soil layer decreased significantly,which indicate that the richness of soil microbial community is decreased and the dominant species are reduced.(4)SOC is mainly distributed in 0~20cm forest soil layer.With the soil depth increases,SOC content decreased sharply in all the forest types;The SOC content of the soil(0~60cm)under bamboo grove is the largest,and that under Pinus taiwanensis forest is the smallest;The average SOC density of different forest types show that the average SOC density of the topsoil(0~20cm)is the largest,and the smallest is Pinus massoniana forest.In 20~40 cm and 40~60 cm soil layers,the average SOC density of soil layer(40~60cm)under bamboo grove is the largest and evergreen-deciduous broad-leaved mixed forest is the smallest;The average SOC density of the soil(0~60cm)under bamboo grove is the largest,and that under Pinus taiwanensis forest is the smallest.According to SOC components,the average ASOC content of the soil under Masson pine forest is the largest,and that under the deciduous broad leaved forest is the smallest;The ASOC / TOC(%)of Pinus massoniana forest is larger than other forest types.Though quantitative evaluation of soil organic carbon pool in Lushan Forest by CPMI,the results show that the improvement of CPMI in Lushan Mountain had different degrees of promotion,and the soil carbon pool in Lushan forest increase with the increase of soil quality.(5)Based on systematically analyzing and investigating soil properties of 8 kinds of forest vegetation types,evaluation indexes select shrub layer(R+H)/ 2,herb layer(R+H)/ 2,thickness of litter layer,thickness of humus horizon,thickness of soil layer,bulk density,clay content,organic content,pH value,CEC,total N,hydrolysable N,available P,rapidly available K,phosphatase activity and so on,which are chosen from species diversity and different forests of soil properties.In this study,processing the data through compositive weighted method calculate its FSHI,and quantifying soil health assessment of 8 forest types.The ranking of soil health of 8 kinds of forest vegetation types are as following: mixed wood > evergreen-deciduous broad-leaved mixed forest > shrub > evergreen broad-leaved forest > deciduous broad leaved forest > bamboo forest > Masson pine forest > Pinus taiwanensis forest.