| Global warming is a hot topic which concerned globally, thus three major greenhouse gases from soil to atmosphere eg carbon dioxide, methane and nitrous oxide were paid attention to in the current research. Forest ecosystem is the important component of terrestrial ecosystems,. and it has significant influence on soil-exchange of greenhouse gases in the atmosphere.The greater xinggan mountains in Inner Mongolia is Chinese important forest ecological system, is also only of Chinese coniferous forest in the cold temperate zone, and it has a unique geographical location and features.This study was conducted in 2013-2014 in temperate zone. the temperal and spatial variation of soil greenhouse gas flux was researched both in field and incubation, and the freeze-thaw cycle in the field and incubation simulation was also been conducted. The results show that:1.Dynamic change of time and impact factors in successive forest. The successive forest variation range of CO2 flux is (21.3±3.9～865.6±93.9) mg·m-2·h-1, CO2 flux were positively correlated with soil surface,5 cm,10 cm,15 cm, and 20 cm depth temperature, and was significant correlation with soil surface,5 cm, to 10 cm,15 cm. At the same time, CO2 flux was negatively related with soil moisture in each layer. The successive forest variation range of CH4 flux is (-15.7±4.1～-270.6±87.1) μg·m-2·h-1,CH4 flux is significant correlation with soil moisture in 10～20 cm.The successive forest variation range of N2O flux is (1.2±0.1～-14.9±2.6)μg·m-2·h-1, The N2O flux and soil temperature showed a negative correlation. At the same time, the N2O flux is significant correlation with soil temperature.2. CO2 emissions from all sites ranged from94.9to1164.0 μg·m-2·h-1, CO2 flux are negatively related with soil moisture in each layer, was positively correlated with soil temperature.Soil temperature and CO2 flux have significant correlation at 5 cm of soil, CO2 flux are negatively related with SOC and TN, CH4 fluxes ranged from -242.0～-42.6 μg·m-2·h-1,CH4 flux are negatively related with SOC,are negatively related with TN.The soil N2O emissions across all of the investigated sites ranged from1.2 to 21.6 μg·m-1·h-1, N2O flux and soil moisture and SOC, temperature were positively correlated, are negatively related with TN.3.Freezing and thawing alternation period of dynamic change and impact factor of greenhouse gas flux, variation range of CO2 flux is (49.4±8.3～329.9±10.2) mg·m-2·h-1, and CO2 flux was positively correlated with soil temperature. CH4 fluxes ranged from (-26.6±2.1～-226.8±31.9)μg·m-2·h-1, CH4 fluxes was positively correlated with soil temperature, and was significant correlation at surface 5 cm and 10 cm of soil, N2O fluxes ranged from (3.4±1.1～14.9±2.6) μg·m-2·h-1, N2O fluxes was positively correlated with soil temperature. Indoor freeze-thaw alternation experiment results show different freeze-thaw cycles and different freezing and thawing temperature were significantly correlated with CO2, CH4 and N2O fluxes. The N2O flux have significant correlated under different mode of operation.4. Accounting the amount of greenhouse gas emissions in growing season and in freezing and thawing alternation period, CO2 flux accounted for about 79.2% in the growing season, and CO2 flux of the proportion is as high as 19.4% in two alternately freezing and thawing period for the whole year. CH4 fluxes is also the main emissions in the growing season, accounting for about 73%, about 25% in freezing and thawing period,is larger proportion in the year; N2O flux is accounted for the proportion of up to 49% during the freezing and thawing, more than his proportion of the growing season, growing season N2O emission flux accounted for only 40% of all the year round. |
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