The Spatial Distribution And Affecting Factors Of Soil Organic Carbon Density Of Forest In Jinggangshan

The small change of the soil organic carbon pool, particularly forest soil organic carbon pool, can significantly change the atmospheric carbon dioxide concentration, which may affect the global climate. Study on dynamics and regulation mechanism of the forest soil organic carbon pool is an important basic work to prediction and control the global climate changed.Taking the five main types of forest soil in Jinggangshan Nature Reserve as the research objects, the paper analyze the spatial distribution of the five forest soil organic carbon density, and comparative analysis the correlation differences between the soil organic carbon density and altitude, annual mean temperature, annual rainfall, pH value, grade with broad-leaved forest and Cuuninghamia lanceolata plantation.(1) The soil organic carbon density of 0～10 cm in 36 sampling sites in Jinggangshan Nature Reserve ranged from 2.82 kg/m2 to7.43 kg/m2, and the average soil organic carbon density was 5.05kg/m2; the soil organic carbon density of 0～100 cm was from 9.92 kg/m2 to 32.33 kg/m2, and the average density was 21.36 kg/m2.(2) The soil organic carbon density of broad-leaved forest in Jinggangshan Nature Reserve was significantly higher than the density of Cuuninghamia lanceolata plantation, while the soil organic carbon density of Bamboo Forest is the lowest. The size order of the average soil organic carbon density of 0～10 cm layer in five kinds of forest types was as follows:mixed coniferous> broad-leaved forest> Magnolia forest> Cuuninghamia lanceolata plantation> Bamboo forest; the size order of the average soil organic carbon density of 11～20 cm layer,21～30 cm layer,31～60 cm layer was as follows:broad-leaved forest> mixed coniferous> Cuuninghamia lanceolata plantation> Magnolia forest> Bamboo forest; and the size order of the average soil organic carbon density of 61～100 cm layer was as follows: broad-leaved forest> mixed coniferous> Magnolia forest> Cuuninghamia lanceolata plantation> Bamboo forest.(3) The soil organic carbon density in broad-leaved forest, Cuuninghamia lanceolata plantation, Magnolia forest, mixed coniferous, Bamboo forest in Jinggangshan Nature Reserve increased with the decrease in the soil depth, the size of the order were as follows:0～10 cm layer> 11～20 cm layer> 21～30 cm layer, 31～60 cm layer> 61～100 cm layer. And the soil organic carbon density in broad-leaved forest, Cuuninghamia lanceolata plantation in Jinggangshan Nature Reserve all increased with the increased in the longitude, and increased with the increased in the latidude. also, the soil organic carbon density in broad-leaved forest, Cuuninghamia lanceolata plantation increased from west to east, and increased from south to north, and the increasing trend of the soil organic carbon density from south to north was more obvious than the trend of the soil organic carbon density from west to east.(4) The soil organic carbon density in the broad-leaved forest first decreased and then increased with the increase in the altitude, while the Cuuninghamia lanceolata plantation increased first and then decreased with the increase in the altitude. The soil organic carbon density in the broad-leaved forest increased significantly with the increase in the average annual temperature, while the Cuuninghamia lanceolata plantation decreased first, then increased, further reduced with the increase in the average annual temperature. The soil organic carbon density in broad-leaved forest significant decreased with the increase in the annual precipitation, while the Cituninghamia lanceolata plantation increased first, then decreased, and further increased with the increase in the annual precipitation. The soil organic carbon density in broad-leaved forest decreased first, then increased, and further decreased with the increase in the grade, while the Cuuninghamia lanceolata plantation increased first, then decreased, and further increased with the increase in the grade. The correlation between the soil organic carbon density in broad-leaved forest and Cuuninghamia lanceolata plantation and the pH value was no obvious. The soil organic carbon content in the forest in Jinggangshan Nature Reserve was significantly negative correlation with soil bulk density.