The Roles Of Netrual Sugars To Carbon Sequestration In Forest Soil At Different Successional Stages

Succession is one of important factors that influence the function of carbonsequestration for forest ecosystem. Neutral sugar accumulation in the soil is closelyrelated to plant carbon input and soil humification process. So, investigating thedynamic changes of neutral sugars in forest soil at different succession stages hassignificant meaning for revealing forest succession and soil carbon sequestration.Dinghushan and Changbaishan which is located in the forest temperate ecosystems,respectively cover the different successional stages from subtropical coniferous forestto broad-leaved evergreen forests, and temperate regions from birch to broad-leavedKorean pine. The concentrations of hydrolyzed individual neutral sugars weredetermined in the different soil layers and the litter at the successional stages ofDinghushan and Changbaishan Mountain forest. By analyzing neutral sugars’distribution, concentration and the influence factors in different succession forest soiland litter under different climatic conditions, combined with the different origin ofneutral sugar to further discuss its accumulation characteristics in soil, we can accessthe contribution to soil carbon sequestration originated from microorganisms andplants carbon. The results show that:1With Dinghushan Mountain forest succession, from coniferous forest tobroad-leaved evergreen forests, concentrations of neutral sugars in the litter range inmasson pine>needle broad-leaved mixed forest>monsoon broad-leaved forest. Theradio (gal+man)/(ara+xyl) is between0.35to1.3.2Concentrations of neutral sugars in soil at different successional stages ofDinghushan Mountain forest gradually decreased with the soil depth. Theconcentrations of neutral sugars in the soil are: monsoon broad-leaved forest> needlebroad-leaved mixed forest>masson pine. Neutral sugars’ relative content increasedfirst then decreased. Compared with the vertical distribution of the neutral sugar andorganic carbon in the soil, the ability of neutral sugars accumulation are strengthened.3With the forest succession, the radio (gal+man)/(ara+xyl) increased first then decreased with the depth of soil profile. Neutral sugars in0-5cm soil layer are mainlyderived from plants, and ranged in the order: masson pine>needle broad-leaved mixedforest>monsoon broad-leaved forest (p<0.05). With the soil depth, neutral sugars insoil at different successional stages of Dinghushan Mountain forest are primarilyoriginated from microorganisms. These results indicate that, needle broad-leavedmixed forest and monsoon broad-leaved forest have stronger soil carbon captureability, and in relation to forest succession, climate, the amount of litter, microbialactions, etc.4With Changbaishan succession, concentrations of neutral sugars in the litterincreased first then decreased, and the radio (gal+man)/(ara+xyl) is between0.6to1.3.5Concentrations of neutral sugars in soil at different successional stages ofChangbaishan Mountain forest gradually decreased with the soil depth.Concentrations of neutral sugars in different soil layers from young forest to matureforest all increased first then decreased, then that from mature forest to old forestgradually increased. Relative content and concentrations of neutral sugars in differentsoil layers at different successional stages of forest has the same tendency. Comparedwith the vertical distribution of the neutral sugar and organic carbon in the soil,difference of relative content of neutral sugars between B soil layer and A soil layer isreduced significantly. The result shows that the relative accumulation degree ofneutral sugars in B soil layer is significantly higher than that in A soil layer.6Neutral sugars in A or B soil layer at different successional stages ofChangbaishan Mountain forest mainly come form microorganisms, and the microbialconversion dropped significantly. These results indicate that rates of carbonsequestration in soil of Changbaishan forest depend on several variables, including theage of stand, soil structure, etc.7Neutral sugars accumulation and conversion in soil at different successionalstages of forest is closely related to soil properties and environmental factors in different areas. Both of concentrations and relative content of neutral sugars inDinghushan Mountain forest soil is smaller than Changbaishan Mountain. With theforest succession, neutral sugars in the surface soil are mainly derived from plants,then primarily originated from microorganisms with the soil depth. In addition, theradio C6/C5sugar in Dinghushan forest soil is higher than Changbaishan forest. Inspite of tree species, soil properties, and climate differences in different areas, theability of soil carbon sequestration was enhanced with the forest succession. However,the rates of carbon sequestration in Dinghushan soil is lower than Changbaishan dueto the more rapid mineralization at higher temperature.