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以海南尖峰岭、霸王岭、五指山、吊罗山、鹦哥岭5个热带原始森林土壤为研究对象,分层采集0–100 cm的土壤样品并分析有机碳含量,用纵向拟合法和分层估算法分别估算其土壤有机碳密度。结果显示:(1)纵向拟合法计算的5个热带原始森林土壤有机碳密度分别为14.98、18.46、16.48、18.81、16.66 kg·m–2,分层估算法分别为14.73、16.24、15.50、16.91、15.03kg·m–2,前者显著高于后者(p<0.05);未经扰动的原始森林土壤,宜采用纵向拟合法计算土壤有机碳密度。(2)5个热带原始森林0–30 cm表层土壤有机碳含量分别占0–100 cm的50.50%、48.56%、43.49%、47.37、42.88%。(3)土壤有机碳密度与森林群落Shannon-Wiener指数(p<0.01)、Simpson指数(p<0.05)、物种丰富度(p<0.01)、土壤容重(p<0.001)存在极显著或显著的负相关关系;与海拔(p<0.05)、土壤孔隙度(p<0.001)、土壤全氮含量(p<0.001)存在极显著或显著的正相关关系;与坡向、林分生物量、平均胸径、平均树高无显著相关关系(p>0.05)。(4)由于海南地处低纬度地区,其丰富的降水和持续高温条件加速了有机质的分解和物质的再循环,导致海南森林土壤碳密度远低于全国平均水平。
Soil samples from 0 to 100 cm were collected and analyzed for soil organic carbon content in five tropical virgin forests in Jianfengling, Bawangling, Wuzhishan, Diaoluo Mountain and Yinggeling in Hainan Province. The vertical fitting and stratification Estimation method to estimate soil organic carbon density separately. The results showed that: (1) The SOC of five tropical virgin forests calculated by longitudinal fitting method were 14.98, 18.46, 16.48, 18.81 and 16.66 kg · m-2, respectively. The stratified estimation methods were 14.73,16.24,15.50,16.91 , 15.03 kg · m-2, respectively. The former was significantly higher than the latter (p <0.05). The soil organic carbon density should be calculated by vertical fitting method in undisturbed forest soil. (2) The organic carbon contents in 0-30 cm topsoil in the five tropical forests accounted for 50.50%, 48.56%, 43.49%, 47.37 and 42.88% of 0-100 cm respectively. (3) There was significant or significant difference in soil organic carbon density with Shannon-Wiener index (p <0.01), Simpson index (p <0.05), species richness (P <0.05), soil porosity (p <0.001) and soil total nitrogen content (p <0.001). There was a significant or significant positive correlation with the slope, stand biomass, average DBH, average tree height was not significantly correlated (p> 0.05). (4) Because Hainan is located in low latitudes, its abundant precipitation and sustained high temperature conditions accelerate the decomposition of organic matter and material recycling, resulting in the carbon density of Hainan’s forest far below the national average.