| In the context of global change, greenhouse gases, like CO2and CH4, are increasing at an alarming rate, the study on the two main greenhouse gases become one of the focus of the current global change research.Currently, the increasing atmospheric concentrations of greenhouse gases were mainly the result of human activities affect, in fact, the natural process is also an important source of greenhouse gases. Soil Carbon, the world’s largest terrestrial ecosystem carbon stocks carrier, plays a very important role in the cycle of global carbon. Forest soil respiration is an important part of soil respiration in the terrestrial ecosystem, which has an important contribution to greenhouse gases emissions, and its changes will have a profound impact on the balance of global carbon.The composition and structure of vegetation community, forest microclimate and soil environment vary greatly under different site conditions. There is a big difference in soil carbon fluxes. To account the forest carbon budget in mid-latitude regions more accurately, comparative study on soil carbon emissions of the temperate conifer forest under different site conditions gets more urgent.Changbai Mountain forest area, located in the southeast of the northeast forest area where is the largest natural forest area in China, is represented by the temperate conifer, and its zonal vegetation (climax community) is broadleaved. Birch and mountain-Yanglin formed after the harvesting disturbance. With the latest portable monitoring system for soil greenhouse gas fluxes, this paper researched the soil CO2and CH4emission flux in different successional stages of the conifer in the north slope of Changbai Mountain Nature Reserve. It is observed synchronously in the field in bare land (farmland abandoned land), grass (artificial turf), soil deciduous forest, secondary birch forest,broadleaved Korean pine, to reveal diurnal variation of soil carbon emissions process from different successional stages of the conifer and environment main relationship control factor for and provide basic data for conifer forest soil carbon, carbon sequestration issue in Changbai Mountain and the calculated basis on the balance of forest carbon (CO2, CH4) payments under the background of global environmental change. The main findings are as follows:(1) Five experimental soil samples are expressed as a dynamic source of CO2and CO2fluxes day emerged a clear single peak maximum occurs at higher temperatures are from12:00to14:00, minimum occurs at a lower temperature in the morning. Day of soil CO2fluxes were the order of the red pine and broadleaf mixed forest> larch red> secondary birch> grass> bare land. Due to differences in community structure and forest canopy density makes good woodland vegetation cover day time CO2flux maximum occurs than bare ground and grass to be postponed. (2) Five soil samples CH4fluxes are negative and there is no obvious diurnal variation of the dynamic rule, the larger the amplitude of diurnal variation, but also the soil to absorb roughly CH4showing high noon evening morning or lower trend. Due to differences in the heterogeneity of soil surface, soil daily CH4flux absorbed descending order of larch> secondary birch> pine and broadleaf mixed forest> bare> grass.(3) Through each of the one-day scale last five plots of soil CO2flux and surface air temperature and0-5cm soil temperature exponential fitting, found a higher correlation coefficient of soil CO2flux and0-5cm soil temperature, and soil CO2flux and temperature emerged positive correlation. Due to the small diurnal variation of soil moisture, soil CO2flux and soil moisture is not relevant. But through the soil CO2flux and soil0～5cm soil temperature and soil moisture multivariate linear regression, correlation coefficient improved significantly, indicating that soil temperature and soil moisture combined effect of soil CO2fluxes. Meanwhile through the soil physical and chemical properties analysis shows that the organic matter content of soil CO2flux effect, and the PH value of the soil CO2flux is no direct relationship.(4) CH4flux through each soil and surface air temperature and soil temperature0～5cm linear fit, the result is five samples of soil and surface air temperature CH4flux correlation coefficient is not high, and the soil temperature the correlation coefficient higher and showed a negative correlation. Soil CH4flux and soil moisture was positively correlated, but the correlation coefficient is not high. CH4flux through the soil and soil0-5cm soil temperature and soil moisture multivariate linear regression, correlation coefficient improved significantly, indicating that soil temperature and soil moisture on soil CH4fluxes together, alone or with soil moisture soil temperature to explain variability of soil carbon flux is not rigorous. Under the premise of good vegetation cover, soil CH4absorption capacity increases PH value increases. Soil C、N content and soil absorption between methane and no apparent direct relationship. |
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