Effects Of Different Vegetation Types On Soil Organic Carbon Storage And Stability In Mountain Forests-arid Valley

The area of mountain forests-arid valley which locates in the upper reach of Minjiang River is a typical ecological fragility area in the western region of china. In the area, except serious vegetation degradation, strong soil erosion andharsh ecological environment, the deterioration of ecological systems is exacerbated greatly for human disturbance. So, these area is one of the key areas where the country is proceeding vegetation restoration, improving vegetation coverage and preventing soil erosion all the time. In this paper, through selecting 8 typical vegetation types to study the distribution of soil organic carbon(SOC) and its reserves, soil aggregates and its SOC reserves, and soil active organic carbon in these area, and initially discuss the influence of vegetation restoration on the storage and stability of soil organic carbon, as follows:1.Different vegetation types affect the concentration and storage of soil organic carbon significantly. the concentration of soil organic carbon of Abies fabri and Picea asperata forests, Quercus aquifolioides forests, Robinnia pseudoscacia and Salix matsudana forests, Berberis aggregata brushwood, Cupressus chengiana forests are significantly higher than Zanthoxylum bungeanum forests and Lyciuchinensem forests(P<0.05). Because of farming and fertilization, the concentration of SOC in 21-30cm and 31-40cm soil depth of Zanthoxylum bungeanum forests and Lyciuchinensem forests are significantly higher than their upper soil, but others decrease with soil depth deepening; SOC mainly focus on the shallow of soil, the inflexion point is 40cm soil layers, and SOC which exists in upper soil is significantly higher than deep soil; SOC in soil profile expresses a distribution trend of power function. From high to low, the storage of SOC in all the vegetation types ordinally are quercus aquifolioides forests (22.83kg/m2)> Robinnia pseudoscacia and Salix matsudana forest (21.60kg/m22)>Abies fabri and Picea asperata forests (17.84kg/m2)> Cupressus chengiana forests (15.98kg/m2)> Berberis aggregata brushwood (14.85kg/m2)>capillipedium parviflorum grasslands (12.61kg/m2) >Lyciuchinensem forests (10.44kg/m2)> Zanthoxylum bungeanum forests (8.85kg/m2),the highest is quercus aquifolioides forests, and the lowest is Zanthoxylum bungeanum forests.2. Different vegetation types affect the stability of SOC by the stability of soil aggregate. There areno significantly difference below 30cm soil depth for NMWD to each vegetation type, however, in 0-30cm, Abies fabri and Picea asperata forests, Quercus aquifolioides forests, Robinnia pseudoscacia and Salix matsudana forests, Berberis aggregata brushwood. Cupressus chengiana forests are higher than Zanthoxylum bungeanum forests and Lyciuchinensem forests.3.Vegetation types are different, and the concentration of soil organic carbon in soil aggregate also have significant differences, especially in large grain diameter aggregate. The SOC concentration of Zanthoxylum bungeanum forests and Lyciuchinensem forests. in each grain diameter aggregate in each soil layers is lower than others; with Zanthoxylum bungeanum forests and Lyciuchinensem forests translated into others vegetation types, the main distribution range of SOC in soil aggregate from<0.5mm grain diameter aggregate turn to 0.5-0.25mm.the total soil organic carbon is a significant positive correlation with SOC in each grain diameter aggregate, and the concentration of SOC in 0.5-0.25mm aggregate is the largest influence factor on total SOC. SOC storage in soil aggregate for defferent vegetation types ordinally are Quercus aquifolioides forests> Robinnia pseudoscacia and Salix matsudana forests>Abies fabri and Picea asperata forests> Cupressus chengiana forests> capillipedium parviflorum grasslands> Berberis aggregata brushwood> Lyciuchinensem forests> Zanthoxylum bungeanum forests. With the vegetation restoration such as Lyciuchinensem forests and Zanthoxylum bungeanum forests turn to others, SOC storage in soil aggregate increase 60%-220%, and>0.25mm large aggregate also increase 2.00-8.48kg/m2.4.Different vegetation types affects the concentration of soil active organic carbon and stable SOC significantly. Compared with Zanthoxylum bungeanum forests, the concentration of soil active organic carbon in Abies fabri and Picea asperata forests, Quercus aquifolioides forests, Robinnia pseudoscacia and Salix matsudana forests, Berberis aggregata brushwood. Cupressus chengiana forests increase 51.70%-414.61%, 50.09%-408.68%,37.17%-228.76%,22.91%-136.41%,50.49%-208.17%,34.24%-237.47 %;compared with Lyciuchinensem forests,which increase 74.37%-230.89% 66.45%-227.38%,6.00%-356.02%,15.28%-283.81%,19.78%-340.76%,1.02%-279.21%. From high to low, the storage of stable SOC ordinally are Quercus aquifolioides forests> Robinnia pseudoscacia and Salix matsudana forests>Abies fabri and Picea asperata forests> Cupressus chengiana forests> Berberis aggregata brushwood> Capillipedium parviflorum grasslands> Lyciuchinensem forests> Zanthoxylum bungeanum forests, and Quercus aquifolioides forests is 144.07% and 118.68% higher than Zanthoxylum bungeanum forests and Lyciuchinensem forests respectively.