Effect of an Unexpected Fire on the Amount of Soil Organic Carbon in Pinus Elliottii of South China
突发性火灾对南方湿地松人工林土壤碳储量的影响

Forest soil carbon pool is an important component of terrestrial carbon pool, and plays a crucial role in global carbon balance. As an integral component of disturbance regime of most terrestrial ecosystems, fire significantly affects the carbon storage and underlying mechanisms that control the carbon balance of ecosystem recovery. Forest fire, natural or artificial, can not only directly consume large amount of soil organic layer, but also indirectly affect soil carbon stock for a long period after the event by altering the physical and chemical properties of the site soil, as well as the canopy cover and vegetation components. In this study, soil organic carbon (SOC) concentration after a wildfire disturbance in a typical Pinus Elliottii of the red soil region in South China was investigated. Soil sampling was conducted in 18 burned sites of different fire intensity two months after the fire, laboratory analysis showed that, SOC in 0~40cm depth decreased the least in the low intensity burning forest land and dropped to 0.69g/100g in the medium intensity burning one, and reached the lowest of 0.44 g/100g(n = 18,F = 17.8,P<0.001) in the high intensity burning sites. The same degree of declining trend also appeared in 0~10cm depth, 10~20cm depth and 20~40cm depth. Compared with soil samples taken at adjacent unburned sites, SOC appeared higher in low and medium intensity burning sites in all depths, and a little lower in high intensity burning. Soil bulk density and soil pH value differed significantly in the three degrees of burning intensity, unlimitedly topped at high intensity burning forest lands, while the result of water content in soil was somewhat inexplicable, implying that more samples and mechanism researches were needed. Results indicated that fire and its intensity can significantly alter soil properties and influence the carbon storage in mineral soil. Uncertainties through the process mainly exist in sampling limitation owing to topographic features and unclear effects of rainfall on soil moisture. To clarify the fire induced consequences on carbon cycle in forest ecosystems in the background of global climate change, understand the ecological effects of forest fire, and consider fire as a useful ecological factor in practice, more studies, especially long-term field studies, should be conducted to specify the process and factors in this effect.