路南石林土壤微生物含量及其对土壤CO_2浓度的影响

MICROBIAL PRODUCTION OF CO_2 IN RED SOIL IN STONE FOREST NATIONAL PARK

在植被生长缓慢的季节(1999年12月),对石林地区红壤三个研究点土下20～60cm不同深度土壤的温度、pH、有机质含量、微生物含量和土壤CO2浓度变化进行了研究。研究表明土壤CO2浓度和土壤中有机碳含量没有直接的关系,但是与土壤微生物含量(Mo)、土壤湿度(Mt)和土壤CO2浓度有很好的相关关系。因此在植被生长缓慢的季节,土壤微生物对土壤空气CO2浓度变化的影响要远远大于来源于根系呼吸的比例。

Lunan stone forest is a kind of typical karst in China, which is mainly developed under red soil. During Dec. 1999, when the plants growing very slow, three study sites were chosen in stone forest national park according to various types of vegetation cover, geomorphology locations and different soil types. CO2 concentration was measured with Gastec pump in different depth of soil (20, 40, 60cm) and at the same time soil samples were gathered and soil properties such as soil moisture, pH, soil organic carbon content, soil inorganic content were analyzed and total number of viable microbes were counted in laboratory. In the study, dependent variable was chosen as the mean soil Log (PCO2), and soil properties were chosen as the independent variables. Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture are the best indicators of the CO2 production, with the equation Log (PCO2) = 0.039(TNM)  0.056(Mo) + 1.215 accounting for 89.5 percent of the variation of the soil CO2 concentration, where TNM is the total number of microbes in the soil and Mo is the moisture of soil sample moisture. This study showed that microbial decomposition of organism is a very important source of CO2 in red soil in Lunan stone forest during the low growing season of vegetation. 