【作者】 郭剑芬；

【导师】 林鹏；

【作者基本信息】 厦门大学 ， 植物学， 2006， 博士

【摘要】 作为重要商品林基地的我国亚热带地区,把大面积常绿阔叶林皆伐后进行全面火烧,是我国南方集体林区经营杉木人工林的主要营林技术环节之一,但大面积火烧将造成迹地养分损失、水土流失、土壤物理性质退化等。营林用火已在温带森林的规定火烧、热带地区的刀耕火种中得到大量研究。早期有关研究主要集中在火烧对N、P等森林生长限制元素的损失及其对森林长期生产力、水文状况、径流化学的影响上;随着人们对全球环境变化的关注,皆伐火烧对生态系统C、N循环的影响研究在近十几年逐渐受到重视,但目前有关皆伐火烧后我国亚热带地区常绿阔叶林C、N动态的研究未见报道。作为森林生态系统主要CO2源的土壤呼吸(约68±4 Pg C·a-1),它的微小变化不但会引起大气中CO2浓度的明显改变,更会影响森林贮存C能力。皆伐火烧后土壤生境条件发生显著变化,土壤呼吸将作出怎样的响应已引起人们的极大关注。目前国外对温带林土壤呼吸的特征、影响因素及其对气候变化的响应等研究较多,如何对土壤各组分呼吸(土壤自养呼吸和异养呼吸)进行有效分离则研究较少。我国对森林土壤呼吸研究则与国外有相当差距,皆伐火烧下土壤呼吸及各组分呼吸动态更未有涉及。本文以福建沙县异州杉木林和栲树林为研究对象,通过野外定位观测和室内分析,在研究皆伐火烧影响林分C、N库和土壤肥力的基础上,着重探讨土壤呼吸及各组分呼吸对皆伐火烧的响应及机制,这对进一步拓展我国森林土壤研究,深入分析森林C汇能力有所裨益,为正确评价森林用火提供重要基础资料,并对我国亚热带山区森林管理者科学用火具有一定指导意义。本文主要得出以下结论:1.皆伐前杉木林C、N库总量分别为238 t·hm-2和8405 kg·hm-2,栲树林的分别为338 t·hm-2和10223 kg·hm-2。两林分乔木层为主要的C贮库,而林分主要N库存在于土壤层。杉木林和栲树林乔木层C库分别占林分C库总量的53%和62%,矿质土壤层N库则分别占林分N库总量的92%和84%。灌木草本层和枯枝落叶层C、N总贮量分别约占林分C、N总贮量的2%。皆伐后杉木林树干(包括树皮)和粗枝中104 t·hm-2 C和287 kg·hm-2 N移出林地,分别占其林分C和N总贮量的44%和3%;栲树林通过树干(包括树皮)和粗枝迁移的C、N量分别为156 t·hm-2和738 kg·hm-2,分别占其林分C、N贮量的46%和7%。两林分皆伐后,土壤C和N贮量发生损失。皆伐后3个月,杉木林和栲树林土壤有机C贮量分别损失26%和32%;土壤全N分别损失12%和11%。可见更多还原

【Abstract】 Chinese fir (Cunninghamia lanceolata) is one of the most important plantation tree species in China in terms of planting area, yield and timber usage. The history of managing this plantation exceeds 1000 years in China. In recent decades, many pure Chinese fir stands were established in the southern part of China for an expected highly economic return, leading to a sharp decline in the area of natural forest of broadleaf trees. It is a traditional silvicultural practice in South China to extablish a plantation of Chinese fir by clear-cutting natural forests, slash burning and site preparation. However, timber harvest and slash burning can cause a substantial loss and redistribution of organic matter and nitrogen. Further, yield decline and land degradation in such disturbed ecosystem have become serious problems, possibly due to high precipitations, steep slopes and fragile soils in this region. How the soil fertility can be maintained in the successively planted Chinese fir stands has received considerable concern. In view of increasing awareness about anthropogenic emissions of carbon as a contributor to global warming and the role of forests as C sinks, information about C and N pools and changes associated with disturbances, including forest management, is needed. Especially, a good understanding on how soil CO2 efflux having been impacted by forest management practices is necessary for predicting carbon sequestration. Many attempts have been made, mainly in temperate and tropical forests, to estimate the changes of C and N stored in world forests associated with clear-cutting and slash burning. Littal has been carried out in forests of southern China, a most important area of subtropical forests in the world. Furthermore, few studies have monitored the components of soil respiration before and after disturbance. The aim of this study is to investiagte in detail the effects of clear-cutting and slash burning on the storages of C and N, soil fertility, soil respiration and its components in a Chinese fir plantation and Castanopsis fargesii forest, located in the Yizhou State Forestry Centre in更多还原