Response Of Soil Organic Carbon To Reclamation And Reforestation In The Huanglong Mountain

Soil organic carbon is a large carbon reservoir and the source and sink of atmospheric CO2, and it has important significance for the accurate prediction of the soil organic carbon dynamics to the diffusion in the atmosphere the failure and repair of the ecological system, which is also the focus of current research. According to the same area and forest land reclamation of abandoned farmland afforestation on soil organic carbon dynamics is weak. This research uses the 13C isotope tracer method on forest Liu Panshan area reclamation organic carbon source and soil organic carbon changes in 4 years,50 years,100 years after the investigation and analysis of organic carbon, abandoned farmland afforestation 18 years,24 years,48 years,100 years and 200 years after the recovery of dynamic process of the determination study on the influence of afforestation,50 forest types on soil organic carbon and soil restoration. The results show that:1.The study area of different years and different layers of the soil organic carbon changes analysis results showed that soil organic carbon in reclaimed rapid initial loss (0.64 Mg/ha/yr), and reclaim the late loss rate becomes slow (0.04 Mg/ha/yr) and gradually becomes more balanced, reach (0.21 Mg/ha/yr). This trend of farmland soil organic carbon and the same trend, namely the loss of most of the organic carbon in previous years after reclamation.2 In After clearing natural forests to agricultural land in the 0-10 cm soil organic carbon content of large aggregates declined 2.0-11.3g/kg,10-20 cm of soil organic carbon content of large aggregates declined 1.9-5.1 g/kg.0-10 cm soil layer, micro-aggregates and <0.053 mm particles were down 1.5-8.9g/kg and 1.5-8.9g/kg; 10-20cm soil layer decreased 1.3-2.6g/kg and 0-2.7g/kg. Similarly soil organic carbon density aggregates similar trends in the 0-10 cm and 10-20 cm soil layer, all aggregates early in the reclamation of organic carbon density than reclaiming the late fall faster.3.After the abandoned farmland afforestation, increase TOC mainly in 0-10 cm soil layer.0-10 cm of soil organic carbon content and density were increased by 5.0-32 g/kg and 8.0-25 Mg/ha; 10-20 cm of soil organic carbon content and density were increased by 3.0-26 g/kg and 7.0-20 Mg/ha. Accumulation rate of 0-10 cm soil organic carbon in soil were significantly higher than 10-20, indicating the accumulation of soil organic carbon after planting is mainly derived from the root litter instead. After planting, the new large increase in the input of organic carbon, organic carbon slow the loss of the original, indicating the accumulation of soil organic carbon is mainly affected by the roots and litter from forest organic carbon input, rather than be affected by the loss of native organic carbon, and particularly evident in the deep soil.4.Organic carbon from woodland roots and litter increases significantly after planting, but which loss slowly from the of farmland soil, which showed that the accumulation of soil organic carbon is mainly affected by the roots and litter from forest organic carbon input, rather than be affected by the loss of native organic carbon, this result is particularly evident in the deep soil.5.After Afforestation 50 years later at Huanglong Mountain, in the 0-20 cm soil organic carbon density is higher than the corresponding 256%-423% of agricultural land. In the area of unspoilt woodland forest soil into cultivated soils than high 526%. Showed that deforestation destruction of organic carbon than afforestation restore organic carbon. Therefore, in the future land use, forest protection is based on the first, followed by afforestation.