| In this paper,6 vegetation types of Abies georgei var.smithii,Quercus pannosa,Juniperus squamata,subalpine meadow,Group Rhododendron spp and Group Rhododendron shrub spp in Jiaozishan National Nature Reserve are taken as the research objects,The plot area is 20m×20m,Collect the leaves,stems,litter,roots and soil of 6 vegetation types in the sample,and conduct indoor experimental measurement and analysis.Through the systematic study on the contents of C,N and P,stoichiometric ratio and ecological stoichiometric internal stability of leaves,stems,litter,roots and soil of 6 vegetation types,the results show that:(1)With the increase of altitude,soil C and N increased,soil P“increased—decreased—increased”.The spatial variation of soil N was the largest and P was the smallest.With the increase of altitude,soil C/N increased first and then decreased,soil C/P“increased—decreased—increased”,soil N/P decreased first and then increased.With the increase of soil depth,the contents of soil C,N and P in each soil layer decreased,the spatial variation of soil C and N was large,but P was relatively small.Soil C/N increased first and then decreased,and soil C/P and N/P decreased.The variation degree of C/P and N/P in each layer of soil profile was higher than that of C/N,indicating that the coupling degree of soil C and N was high.The results of redundancy analysis showed that the Soil p H,bulk density and altitude are the dominant factors affecting soil C,N,P and stoichiometric characteristics.Soil texture also has a significant impact on it,while silt and soil moisture content have no significant impact on it.(2)(1)With the increase of soil depth,the contents of C,N and P in the six vegetation types decreased,and there were significant differences(P<0.05).The variation ranges of soil C,N and P contents were 34.47?274.81g·kg-1,0.46?12.68g·kg-1 and 0.33?3.47g·kg-1 respectively;The contents of C,N and P in the soil of 6 vegetation types were Group Rhododendron shrub spp>Group Rhododendron spp>Juniperus squamata>Quercus pannosa>subalpine meadow>Abies georgei var.smithii,Group Rhododendron shrub spp>Juniperus squamata>Group Rhododendron spp>Quercus pannosa>subalpine meadow>Abies georgei var.smithii,Juniperus squamata>Group Rhododendron shrub spp>subalpine meadow>Group Rhododendron spp>Abies georgei var.smithii.On the whole,the contents of C and N in the soil of Abies georgei var.smithii are lower than those of the other five vegetation types.This is because the litter of Abies lanceolata forest contains tannin resin which is difficult to decompose,and the decomposition rate of the litter is slow.The acid substances produced in the decomposition process will lead to the acidification of the soil,affect the microbial activities,and then reduce the input of soil carbon and nitrogen content.(2)6 the contents of C,N and P in the same component of vegetation type and different components of the same vegetation type showed significant differences(P<0.05).The variation ranges of C content in roots,stems,leaves and litter leaves of 6 vegetation types were 411.25?470.76g·kg-1,391.34?563.81g·kg-1,411.20?551.78g·kg-1 and 378.16?524.02g·kg-1 respectively,The variation range of N content is 2.06?9.20g·kg-1,3.85?12.77g·kg-1,4.61?20.40g·kg-1 and 3.11?15.83g·kg-1 respectively,The variation range of P content is 0.79?1.44g·kg-1,0.70?1.32g·kg-1,0.91?1.90g·kg-1 and 0.48?1.33g·kg-1 respectively.(3)Except for Group Rhododendron spp,the C content of leaves of other five vegetation types is higher than the global average value of plant leaves,indicating that the carbon sequestration ability of leaves of Abies georgei var.smithii,Quercus pannosa,Juniperus squamata,subalpine meadow and Group Rhododendron shrub spp is strong;The C content of litter leaves in subalpine meadow is much lower than that of other 5 vegetation types,which is due to the less accumulation of litter leaves in the aboveground part of subalpine meadow than other vegetation;The content of C in roots and stems of all vegetation types was significantly higher than that of N and P.(3)(1)The soil C/N,C/P and N/P of 6 vegetation types showed different trends with the increase of soil depth,and all showed significant differences(P<0.05).The variation ranges of soil C/N,C/P and N/P were 9.96?89.94,20.17?165.15 and 0.43?9.22 respectively;The soil C/N,C/P and N/P of six different vegetation types are subalpine meadow>Group Rhododendron spp>Quercus pannosa>Group Rhododendron shrub spp>Juniperus squamata>Abies georgei var.smithii,Group Rhododendron spp>Abies georgei var.smithii>Group Rhododendron shrub spp>Quercus pannosa>Juniperus squamata>subalpine meadow,Abies georgei var.smithii>Group Rhododendron spp>Group Rhododendron shrub spp>Quercus pannosa>Juniperus squamata>subalpine meadow.The soil C/N of Abies georgei var.smithii is lower than that of the other five vegetation types because its C content is significantly lower than that of the other five vegetation types.(2)6 the C/N,C/P and N/P of the same vegetation type and different components of the same vegetation type showed significant differences(P<0.05).The C/N variation ranges of roots,stems,leaves and litter leaves of 6 vegetation types were 45.03?214.3,36.40?147.42,23.97?112.39 and 24.31?166.72 respectively,the C/P variation ranges were 287.16?548.02,352.88?587.03,249.98?607.59and 285.51?914.27 respectively,and the N/P variation ranges were 1.45?11.69,3.43?9.70,4.91?10.73 and 4.01?11.96 respectively.(3)The leaf C/P and N/P of subalpine meadow were lower than those of other vegetation types,indicating that subalpine meadow had higher growth rate;According to the theory of nutrient limitation thresholds 25,14 and 16,the growth of six main vegetation in jiaozi mountain is limited by N,and the decomposition of litter is mainly limited by N.(4)According to Garnier's theory,in the process of plant growth,the growth of stems of Abies georgei var.smithii is limited by N,the growth of roots of Juniperus squamata and subalpine meadow are limited by P,and the growth of leaves of Abies georgei var.smithii,Quercus pannosa,Juniperus squamata,Group Rhododendron spp and Group Rhododendron shrub spp are limited by N and P.(4)Six vegetation types of the roots,stems,leaves and fallen leaves of different vegetation types have different internal stability indexes,and the internal stability of each component of different vegetation types is different;The internal stability index of roots,stems,leaves and litter of different vegetation types showed a change trend that C and n elements were higher than P elements;The internal stability of different elements in different organs of different vegetation types shows that the aboveground part and underground part show roughly the opposite change trend. |
PDF Full Text Request