中文摘要：

火作为影响森林生态系统的一个生态因子，既可能有利于维持生态系统的平衡与稳定，也可能会破坏系统的结构和功能，甚至引起生态系统的失调或崩溃。森林碳储量是陆地生态系统碳库的重要组成部分，研究火烧对土壤有机碳和理化属性的影响，对认识自然或人为干扰下森林生态系统碳储量的变化具有重要意义。本文通过选取2007年5月南方红壤丘陵区典型人工针叶林中一次突发性火灾后形成的一块火烧迹地，划分不同火烧强度，进行土壤调查取样和室内实验分析。研究结果表明，火灾发生2个月后，高强度火烧和中强度火烧下，0～40cm的土壤剖面有机碳储量相比低强度分别降低了61．4％和39．5％；0～10cm、10～20cm和20-40cm等3个土层上，土壤有机碳储量的大小均呈现出低强度火烧〉中强度火烧〉高强度火烧的一致趋势。土壤理化性质方面，中、高强度火烧迹地上土壤容重相比低强度火烧有增大趋势，高强度火烧迹地土壤pH值最高。

英文摘要：

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 soi