Study On The Ecological Stoichiometry Characteristics Of Typical Vegetation Communities In The Jingbo Lake Karst Platform

The soil of Jingpo Lake is a kind of entirely new basalt soil,which originated from the volcanic eruption of recent stage.There were several kind of soil types because of the different rock weathering levels,and these may also led to the different stages of vegetation substitution.We could observe several kinds of vegetation communities from the edge to the central zone along the volcanic regions.And this special vegetation substitution series could be an ideal system to study the relationship between the plant and soil.We investigated the ecological stoichiometric characteristics of plant leaf and root,soil and soil microbial community by comparing the different vegetation communities.The study will support the important base of theory for the conservation and development vegetations on the lava plateau of jingpo Lake.We selected the herb,dwarf shrub,high brush,deciduous forest,conifer and broadleaf mixed forest as the target vegetations.We combined the field investigation and lab analysis to measure the concentrations of nutrients from plant,soil and soil microbes to classify the limited nutrient for plant growth and development in this region.Some conclusions are as followed: 1.The N/P values of leaves of different vegetations were less than 14,which demonstrated the growth of plant on lava plateau of Jingpo Lake were mainly limited by nitrogen(N).The tendency of N/P varied along the vegetation substitution was hump-shape,the peak was on the middle stage of substitution,which higher than the early and late stages.2.the concentrations of C,N,P,K among the tree,shrub and herb of these vegetations showed the significant differences.C concentrations of tree was highest compared to those of shrub or herb,while as the P and K concentration of herb were relative higher than those of tree and shrub.3.For the soil,the concentrations of nutrients were significantly different among five vegetation stages.Results showed the sequence was C > K > N > P.The highest C concentration was found in the conifer and broadleaf mixed forest,however,the K concentration was lowest than other vegetation soils.The soil C concentrations were positive to the substitution,which may related to the litter fall decomposition of the vegetations.The N and P concentrations of both hush and dwarf shrubs were significant higher than herb or forest vegetations.4.The soil microbial carbon(MBC)were not significantly differed for all the vegetations,but it did not the same as soil microbial nitrogen(MBN),which were significant differences among vegetations.The MBC/MBN had good negative relationship with the vegetation development,which demonstrated the soil microbial communities varied with the vegetation substitution.The concentration of MBC and MBN were both lowest for the herb soils.It demonstrated the C and N sources from active organism were low and nutrient turnover was also low in the early stage of substitution.Thus the soil fertility was also lowest for the herb soils.5.There were significant differences of C concentration of plant leaf and root for all the vegetations,but there were not marked differences for those of N and K.