气候变化及人类活动对中国土壤有机碳储量的影响

对中国1998年第二次土壤普查中的2000多个土壤剖面中碳储量与年平均温度(T)、年降水量(P) 的相关性研究表明:它们之间的相关性在不同的温度带下具有很大的差异,在T ≤10 oC的地区,土壤有机碳储量与温度的负相关性最强;在10 oC< T ≤20 oC的地区,受与降水正相关的影响,土壤有机碳储量与年平均温度表现出一种正相关性;而在T > 20 oC的地区,土壤有机碳储量与温度和降水的相关性都很差。由于温度和降水在中国存在很强的正相关性,因此在相关分析中宜采用偏相关分析方法。受人类耕种的影响,耕地土壤有机碳储量与温度、降水相关性远低于非耕地土壤。对具有相同土壤属性和气候条件的同一地区的耕地土壤与非耕地土壤样本进行的配对检验表明,耕地土壤与非耕地土壤有机碳储量之间存在显著差异,土地利用的改变在总体上导致了土壤碳的释放。

Impacts of Climate Change and Human Activities on Soil Carbon Storage in China

More than 2000 soil samples obtained from the second soil census in China in the year 1998 were applied to analyse the correlations of soil organic carbon storage (SOC) and climatic factors, including annual mean temperature (T), and sum of precipitation (P). The results show that: (1) the correlations are quite different in different temperature zones. In the area where T ≤10^oC, the correlation between SOC and temperature has the strongest negative correlation. In the area where 10^oC < T ≤20^oC, a positive correlation appears under the influence of precipitation. In the area where T > 20 ^oC, the correlation between SOC and temperature and precipitation is inadequate. (2) Due to the strong positive correlation between temperature and precipitation in China, the partial correlation method is thus better than Pearson correlation method. (3) The correlation between SOC and temperature and precipitation in cultured soil is weaker than that of non-cultured soil, which could attribute to human activities. (4) 26 pairs of soil samples, each pair coming from the same place which has the same soil properties and the same climatic condition, and consisting of one sample in cultured soil and the other in non-cultured soil, are used to analyse the difference of soil organic carbon storage between cultured and non-cultured soil. The results show that the differences of SOC are significant in two types of soils, and as a whole there is certain SOC released to the atmosphere as forest or grassland is converted to cropland.