| Forest fire was the most important factors in forest ecosystem, Global warming causes frequent forest fires, it destroyed a lot of trees, making organic carbon into inorganic carbon. It also makes concentration of CO2 increase in the short time and increases the amount of greenhouse gases. The present study forest fires contribution to the carbon content in the atmosphere was also a hot spots. Forest fire could changed soil properties and soil microbial quantity. Different intensity of fire produce different effects.We selected four different time series after heavy fire in Larix gmelinii forest of Inner Mongolia, the effects of fire on soil properties and greenhouse gas flux have been studied in 1986、1995、2006 and 2014 burned area respectively. We took soil samples from the four burned forest areas in different time series and their corresponding not burned areas (based as control). In addition, the post-fire forest sites both occurred in 2003 and 2000 in Chaocha state forest farm of Genhe city were selected as research area, the unburned forest area which has not been fired was selected as control. The number of soil bacteria, fungi and actinomycetes in the natural recovery after different forest fire intensity were investigated which occurred 13 years and 10 years later. The results show that:(1) Soil CH4 absorbing flux has decreased significantly after fire, especially in the fire occurred year, this change would be terminated when fire occurred 28 years later. Soil CH4 absorbing flux decreased 51.0%、45.0%、7.1% after 0,8 and 19 years respectively. Soil CO2 emission flux has increased 64.5% after fire occurred year when compared with the control, but the effect of different time series fire have no obvious uniformly results. Soil N2O emission flux has increased 64.5% after fire occurred year when compared with the control (139.3μg·m-2·h-1). Soil N2O emission have decreased 5.6%、14.6% and 37.9% after fire occurred after 8、19 and 28 years respectively.(2) Soil pH have increased 7.7%、2.0%、3.4% and 4.0%, soil organic matter have decreased 63.8%、26.6%、35.3% and 11.3%, soil total nitrogen content have decreased 53.2%、19.7%、21.7% and 16.2% after 0、8、19 and 28 years respectively when compared with their corresponding control.Soil available nitrogen content have decreased 28.1% and 9.5% after 0 and 8 years respectively, but increased 16% after 19 years when compared with their corresponding control, and there was no significant difference among the burned area and control when forest fire occurred 28 years later. Strong correlation among soil CH4 and CO2 flux and among soil N2O flux and soil total nitrogen have been found.(3) Occurred 13 year later in burned area the soil microbial number than microbial generally high. After burning soil bacteria, fungi, actinomycetes average increased by 99.8, 93.8,100.5×104/g. The result shows that asignificant increase in the number of microorganism trend based on the analysis of variance. The numbers of microorganism also increased significantly 10 years alter. The number of bacteria, fungi and actinomycetes were increased 96.2.6×104/g,117.2×104/g,105.6 ×104/g in average. There was no significant relationship between different soil layer for soil microbe both in Aoxiang and 3 km area. |
PDF Full Text Request