| In recent years,the research on the mechanism of soil organic carbon mineralization and its sensitivity to soil temperature has become a hot issue in this field.In terrestrial ecosystems,the addition and input of exogenous carbon directly affect the balance of soil organic carbon pools and the status of soil structure and so on,and therefore it will certainly affect the balance and transformation of soil organic carbon in the global terrestrial ecosystem.Understanding the mineralization produced by the input of external carbon into the soil and the dynamic growth characteristics of the microorganisms in the soil are important for the future development of soil organic carbon cycling in terrestrial ecosystems.In this paper,we studied the Quercus liaotungensis and Populus euphratica forests in Ziwuling forest area of Gansu Province.We used field sampling and indoor simulated culture experiments to measure different forest layers and different soil layers(0-10cm;30-50cm)and different temperatures(15°C;25°C)Soil respiration rate in spring and autumn,and using the corresponding formula to fit the soil organic carbon mineralization,soil respiration temperature sensitivity and soil microbial growth parameters,and obtained the corresponding research results:(1)Soil samples recovered from Populus davidiana forest and Quercus liaotungensis forest were cultured under laboratory conditions and in dark conditions under certain humidity conditions at 15°C and 25°C.It was found that as the culture time prolonged and the temperature was increased,The increase has a positive correlation with the cumulative carbon mineralization of the soil.The accumulated organic carbon mineralization of the poplar forest and the deep soil of the Quercus liaotungensis is higher than the cumulative carbon mineralization of the shallow soil,but the poplar The trend of soil organic carbon mineralization in forest lands decreases after increasing.(2)The soils of Populus davidiana forest land and Quercus liaotungensis forest land were cultured under different temperature conditions at 15°C and 25°C,except that the temperature sensitivity of the shallow soil layer of Quercus liaotungensis changed little.The deep soil of Quercus liaotungensis and the poplar forest were shallow.The temperature sensitivity of decomposition of organic carbon in layers and deep soils is significantly enhanced;the temperature sensitivity of organic carbon decomposition in shallow soils is higher than that in deep layers,indicating that the adaptability of shallow soil microorganisms at different temperatures is not so obvious that their depth The readily decomposable organic carbon in the Tibetan soil is more easily utilized;in addition,the temperature sensitivity of organic carbon decomposition in the shallow and deep layers of Populus davidiana forest is lower than that in the soil of Quercus liaotungensis.(3)By observing the spring and autumn of Populus davidiana forest and the shallow and deep layers of Quercus liaotungensis,the soil respiration rate will increase after the addition of glucose solution,and the seasonal change will be analyzed by combining the kinetic parameters of microbial growth after the fitting of Mie equations.The impact on the growth of soil microorganisms in Populus davidiana forest and Quercus liaotungensis was affected.At the same time,the differences between seasons also had a significant impact on the observed organic carbon content,the mechanism of microbial growth selection,and the sensitivity of soil heterotrophic respiratory temperature.The content of available organic carbon in the soil of Populus davidiana forest was significantly higher than that in spring in autumn,but the content of easily degradable organic carbon in soil of Quercus liaotungensis in different seasons did not change significantly.The temperature sensitivity value indicating the degree of affinity of the microorganism to the substrate is almost indistinguishable under different season conditions. |
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