| Larix gmelinii forest area is the largest of coniferous forests in north China, is an important carbon sink of China, and has important influence on Chinese sequstration and the global climate change. Because of its highly humid, cold and frozen environment, the dynamics of absorption and release of soil CH4in Larix gmelinii forest is different from others. Therefore, the research on soil CH4dynamics and its relationship with environment has an important theoretical and practical significance to reveal the local forest carbon dynamics and its effect on climate change. Study sites were selected in different slope positions of four kinds of typical Larix gmelinii forest communities in Inner Mongolia Genhe national ecological research station and done in May to September of2011and2012. The CH4were collected by static box and analyzed by an automatic cavity ring-down spectrophotometer, and measured the soil temperature of different depth and soil moisture content as well, Using variance, correlation analysis and other statistical methods, we studied the diurnal and monthly changes of soil CH4fluxes, and analyzed the effect of soil temperature and moisture content on CH4fluxes. Results showed as follow:(1) The diurnal variation of CH4fluxes:Soil CH4in hilltop emitted all the day, the average flux of top slope is-309.51μg·m-2·h-1, absorption at night is greater than daytime, CH4fluxes has no correlation with temperature.(2) The monthly variation of CH4fluxes:Soil CH4fluxes of top slope and upper part of slope were absorption is greater than emission, the average flux are-2.11μg·m-2·h-1and-49.08p.g·m-2·h-1. Soil CH4fluxes of lower part of slope and bottom of hill were emission is greater than absorption, the average flux are9.78μ·m-2·h-1and37.96ug·m-2·h-1. CH4fluxes in different slopes exist significance level, the monthly changes of soil CH4fluxes in different slopes also exist significance level.(3) The interannual variation of CH4fluxes:Soil CH4fluxes of Larix gmelinii forest in2011was absorption is greater than emission, the average flux is-21.50μg·m-2·h-1, soil CH4fluxes in2012was emission is greater than absorption. Soil water content increased significantly inhibit soil CH4oxidation, Lead to CH4emission flux increased.(4) CH4fluxes of top slope and upper part of slope have certain correlation with temperature and soil water content at all times during the observation, but have no correlation in lower part of slope and bottom of hill, shows that the influence of environmental factors on CH4fluxes in different slopes exist significance level.(5) The process of permafrost melting has little effect on soil CH4fluxes, process of soil drought-wet change has significant negative correlation with CH4fluxes, indicates that the soil water content is one of the important factors affecting CH4fluxes. |
