【作者】 杨少红；

【导师】 杨玉盛；

【作者基本信息】 福建农林大学 ， 森林培育， 2006， 硕士

【摘要】 全球土壤有机碳库约为1550Pg，约是陆地植被总碳储量的3倍、大气碳库的2倍。土壤每年以土壤呼吸形式向大气排放的60～80PgC，是人类燃烧化石能源排放到大气的12～16倍。由于人口的增加、人类活动的不断增强，土地利用和土地覆被发生了巨大变化，从而使更多的碳素释放到大气中，土地利用变化影响下相应CO₂的释放已不容忽视。据报道，每年因土地利用变化所释放的CO₂约占全球CO₂释放量的25％。 我国亚热带山地丘陵红壤区山高坡陡、降雨量大且集中。由于人口密集，加上经济快速发展，人类活动已使本区域的土地利用方式发生了巨大的变化。大面积天然林经皆伐、炼山和整地后改为人工林、次生林、经济林和农田。红壤区由于土壤有机碳库储量不高，土壤有机质含量的变化是红壤区域土壤质量与土壤持续能力的重要表征。本地区土地利用的变化引起了人们的高度关注，鉴此本文在福建建瓯市选择了细柄阿丁枫天然林、木荷和杉木人工林、封山育林地、锥栗林、柑橘园和坡耕地七种闽北典型的土地利用方式，通过野外定位观测和实验室分析，研究了土地利用变化对土壤碳库、可溶性有机碳、轻组有机碳、微生物生物量碳以及土壤呼吸的影响。 研究结果表明： （1）不同土地利用方式土壤有机碳含量总体上随着土壤深度的增加而减少。其中天然林、人工林、次生林整体上比经济林和坡耕地下降的幅度大。土地利用变化对表层土壤的影响显著高于底层土壤，0～5cm土层有机碳含量和储量受土地利用变化的影响最大，而0～20cm土层土壤有机碳储量占0～100cm土层的30.43％～40.86％，成为贮存有机碳的主要层次，40cm以下土层有机碳含量与储量受土地利用变化的影响很小。 （2）0～100cm土层土壤有机碳储量大小顺序为：细柄阿丁枫天然林＞杉木人工林＞柑橘园＞锥栗林＞木荷人工林＞封山育林地＞坡耕地，其中细柄阿丁枫天然林SOC储量分别比木荷人工林、杉木人工林、封山育林地、锥栗林、柑橘园和坡耕地的高55.17％、36.53％、75.44％、45.91％、44.07％和86.10％。 （3）不同土地利用方式土壤可溶性有机碳含量总体上随土层加深而降低，0～5cm土层DOC含量为40～60cm土层的2倍左右。其中细柄阿丁枫天然林0～5cm土层的DOC含量最高1682.08mg·kg^-1。锥栗林的最低(904.19mg·kg^-1)。 （4）不同土地利用方式随土壤剖面深度增加，轻组含量、轻组有机碳占总有机碳比例均明更多还原

【Abstract】 The soil organic carbon pool is about 1550Pg, which is 3 times of vegetation’s carbon storage, 2 times of atmosphere. The soil let 60⁸0Pg C to atmosphere with the soil respiration annually, which is 12¹6 times of the burn of fossil energy. Due to the growth of population and the human’s active, the land use and land cover have been changed greatly. So more carbon was released to atmosphere and people has attached importance to the release of CO₂ lead by the change of land use. It was reported that the CO₂ released by land use change was about 25% of the globe.The mountains are high and steep in the red soil region of sub-tropic in China. The rainfall is great and concentrates. As a result of high population’s density and the quickly development of economy, human’ s action have greatly changed the mode of land use. Many natural forests which were clean-cut 、slash burned and land prepared, were changed to plantation forests, secondary forests, orchards and steep farmlands. The storage of organic carbon in red soil region is low, so the content of soil organic matter is important symbolization of the soil quality and sustainability. People have attended to the change of land use. Therefore we chose different land uses mode including :the Altingia gracilipes natural forest、 the Schima superba and Cunninghamia lanceolata plantation forest, secondary forest、Castanea henryi and Citrus aurantium orchards and steep farmland in Jianou City of Fujian Province. We researched the effect of land use changes on the soil carbon pool, dissoveled organic carbon、light fraction organic carbon、microbial biomass carbon and soil respiration.The major results were summarized as follows:（1） Soil organic carbon contents decreased with soil depth increasing in different land utilization types, in which the drop extent of natural forest, plantation forest and secondary forest was bigger than orchard and steep farmland. The effect of land use change on the surface layer soil was more significant than on the substrate soil, in which the influence to soil organic content and storage in 0⁵cm soil layer is most great. Soil organic carbon storage in 0²0cm was 30.43%⁴0.86% of that in 0 100cm soil layer, so the soil layer of 0²0cm is main. The influence to SOC content and storage in 0⁴0cm soil layer was few.（2） The order of soil organic storage in 0 100cm soil layer : Altingia gracilipes natural forest> Cunninghamia lanceolata plantation forest > Citrus aurantium orchard > Castanea henryi orchard > Schima superba plantation forest > the closing land for reforestation>steep farmland. The SOC storage of Altingia gracilipes is 55.17%, 36.53%, 75.44%, 45.91 %, 44.07% and 86.10% higher respectively than Schima superba, Cunninghamia lanceolata forest plantation, the land closing for更多还原