Using forest site patches to estimate the soil organic carbon pool in the puli and luanda forest working circles

Abstract

The soil organic carbon pool is significantly influenced by certain environmental factors, such as elevation, topography, and vegetation type. In this study, we used the forest site patch method, divided or merged by elevation (0∼1499, 1500∼2499, and ≧ 2500 m), aspect (N-NE, E-SE, S-SW, and W-NW), slope (0°∼15°, 16°∼35°, and ≧ 36°), and forest type (plantation and natural forests), to estimate the soil organic carbon pool in the Puli and Luanda Forest Working Circles. The areas of the Puli and Luanda forestland were about 27,132 and 57,545 ha, which could be compartmented into 55 and 65 patches, respectively. The results showed that total contents of soil organic carbon estimated by this study were about 5.29 Tg and 13.0 Tg, and the contents of fine soil organic carbon were 3.51 Tg and 7.71 Tg in Puli and Luanda forestlands, respectively. Soil organic carbon and the fine soil organic carbon content increased with elevation; the highest carbon content was observed at mid-elevations followed by a slow decline at higher elevations. The soil organic carbon content for different aspects was in the order of E-SE > S-SW > W-NW > N-NE. Furthermore, interactions of factors of this study that highly influenced soil and fine soil organic carbon contents showed that each patch significantly differed from each other. This demonstrates that the forest site patch method can express different soil carbon pools among all forestland patches types. Thus, the method provides a satisfactory mode system to estimate soil organic carbon pools in complicated landforms.