In order to understand the effect of freezing and thawing process on the content of organic carbon in forest soil,the spatial and temporal characteristics of the soil particle composition,light recombination and the content of the organic carbon with the freezing and thawing process of 5 forest types(Pinus sylvestriformis,Quercus mongolica forest,Secundaria saltus Betula,Koreanpinebroad-leaved forest and Hardwood broad-leafed forest)in Changbai Mountain were studied by in situ culture method.The results of the study were as follows:1.The rule of the composition and content of organic carbon of the 5 forest types in 0-20 cm layer were the same during the freezing and thawing process,all of which showed that the proportion and content of soil coarse grain components were significantly higher than those of fine particles and content.The freezing and thawing process had different influences on the composition of soil organic carbon composition,the freezing and thawing process had little influence on soil coarse grain components in 0-10 cm and soil fine particle composition in 10-20 cm during the early to middle stage,but the latter,the effect of freezing and thawing resulted in a significant decrease in the proportion of coarse grain fractions in 0-10 cm,and the proportion of fine particles increased significantly in 10-20 cm.2.In the process of freezing and thawing,the content of organic carbon in the soil coarse particles was significantly higher than the organic carbon in fine particulate in the upper and lower layers of the 5 forest types,and the content of particulate organic carbon had the same spatial distribution pattern in the 5 forest types during the whole freezing and thawing process,that is the content of the coarse and fine particulate organic carbon in 0-10 cm layer soil was significantly higher than that in 10-20 cm soil.The response of the 5 forest types to the freezing and thawing process is different.The stability of the soil organic carbon in the soil of the Pinus sylvestriformis is obviously lower than the other 4 kinds of forest soils.The composition of the soil particles in the Quercus mongolica forest is most sensitive to the freezing and thawing process,while Koreanpinebroad-leaved forest,Hardwood broad-leafed forest and Secundaria saltus Betula are similar in soil structure stability and organic carbon stability and are better than others.3.In the process of freezing and thawing,the proportion of recombinant components was significantly higher than light components in the upper and lower layers of the 5 forest types,and there was a spatial distribution characteristic:the proportion of the structure of the recombined components of the soil increased,while the proportion of the light group composition decreased with the increase of soil depth.With the process of freezing and thawing,there is a certain time dynamic law in the five types:the soil layer recombination in the first medium of freezing thawing increases with time,and the change law of the light group is just the opposite.4.During the freezing and thawing,the content of light recombined organic carbon of 5 forest type in upper soil decreased with the deepening of the soil layer.While the content of light recombined organic carbon changed with freezing and thawing,but there was no obvious rule.To sum up,the influence of freezing and thawing on the five kinds of forest type soil particle components and the light recombination fraction is greater,and it had a uniform change rule,but the content of particulate organic carbon and light recombinant organic carbon is affected by freezing and thawing,but it had a great change,and it did not have a uniform change rule,and the change of each soil layer was different. |