Effect Of Different Regeneration Methods On Organic Carbon Stability Of Soil Aggregate In Subtropical Forests

Forest soil carbon pool, which accounts for70%of global soil organic carbon pool, is2-3times of the forest biomass carbon pool and1.4times of Atmospheric carbon pool; so a tiny change in Forest soil carbon pool can result in remarkable change in Atmospheric CO-2-concentration. Soil carbon deposition is influnenced by regeneration methods in two ways:soil organic magnitud (carbon storage and deposition rate) and quantity (soil organic carbon stability). The former one is an important factor on soil organic carbon’s long-term deposit. The distribution of aggregate affects the coverage and the stability of carbon in the background of the global climate change; the study of soil aggregate attracts more and more attention. However, there is still lack of understanding about influence and mechanism of different regeneration methods on soil aggregate organic carbon stability, thus this becomes key and urgent content of the global carbon cycle.This study chooses six forest (natural forest, natural regeneration forest, promote update forest,Castanopsis carlesii plantation, Cunninghamia Lanceolata plantation and Pinus massoniana Lamb plantation)as research object in subtropical areas, which the background conditions are consistent, promulgate cognition about soil carbon stability mechanism. By studying the effect of different regeneration methods, on soil aggregate organic carbon and component (free low-density fraction organic carbon、 mineral-associated low-density fraction organic carbon、intra-aggregate particulate organic carbon、intra-aggregate mineral-associated organic carbon), the study provides data base for the effect mechanism of different regeneration methods on soil carbon deposition. And it also provides thread for scientific application of forest regeneration methods in subtropical areas.The research shows as follow. Different regeneration methods have effects on soil aggregate carbon fraction. Nature forest change to natural regeneration forest, promote update forest or plantation through different management. The free and mineral-associated LF, intra-aggregate POM, intra-aggregate mSOC vary from its changes However, contrary to results of former researchs,Castanopsis carlesii plantation become more pure and underground biomass is less because of removing other tree species. But the number of overground biomass is great, so its organic carbon is just second to nature forest, and higher than other forests. Aggregate carbon in all size represent changes, among which macro aggregate contribute most. As sensitive factor to forest management LF and POM represents regular pattern; coarse particulate organic carbon loss is more than fine particulate organic carbon. It shows that iPOM in subtropical areas is more sensitive to regeneration methods. This study also finds that macroaggregate turnover model that iPOM in microaggregate decides soil organic matter stability does not apply to subtropical areas, which settles foundation on soil organic carbon stability mechanism further.