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基于CO2FIX模型的燕山北部山地华北落叶松人工林碳动态研究

标题: 基于CO2FIX模型的燕山北部山地华北落叶松人工林碳动态研究
英文标题: Research on Carbon Dynamic of Larch Plantation in North Region of Yanshan Mountain Based on CO2FIX Model
作者: 贾彦龙
出版时间: 2012-01-01
所在大学: 河北农业大学
关键词: 华北落叶松人工林,碳动态,CO2FIX模型,轮伐期,燕山北部山地
英文关键词: Larch plantation,Carbon dynamic,CO2FIX model,Rotation,North region of Yanshan Mountain
论文级别: 硕士
学位: 学位论文
导师: 许中旗
专业: 生态学
提交时间: 2012
摘要: 我国拥有世界上面积最大的人工林,在吸收大气CO2方面发挥了重要作用.但人工林的碳汇功能是一个动态变化的过程,并受到抚育间伐及其轮伐期的影响,从生物量碳、土壤碳和木质林产品碳等方面来全面认识人工林的碳汇作用及其动态变化过程具有重要的科学和现实意义.本研究以我国华北地区山地主要树种华北落叶松为研究对象,通过CO2FIX V.2模型模拟方法,从林分尺度研究燕山北部山地华北落叶松人工林及其木质林产品的碳动态,同时通过分别设置不同的轮伐期、温度及降水情景模式,研究了轮伐期、温度及降水变化对华北落叶松人工林碳动态的影响.研究的主要结果为:(1)在承德围场地区现行的轮伐期体制下,华北落叶松人工林总碳储量以轮伐期(50年)为周期呈现周期性变化,变化范围大致在150-200 t?hm-2之间.在每个周期内,总碳储量表现为先降低,然后升高,最后降低的整体趋势.在华北落叶松人工林三个碳库中,土壤碳储量、生物碳储量、木质林产品碳储量对总碳储量的贡献率的均值分别为77%、17%和6%.同时,在林分发展的不同时期,各碳库对总碳储量的贡献率有所不同.(2)华北落叶松人工林生物碳储量随时间呈周期性变化,变化范围在0-55 t·hm-2之间.在每个周期内,生物碳储量呈波浪式的消长;土壤碳储量在每个周期内变化规律一致,土壤碳先降低后波浪式上升,最后恢复到接近初始的水平,碳储量变化范围大致在130-160 t?hm-2之间.同时,土壤碳以轮伐期(50年)为周期随时间有整体下降的趋势,后一周期较前一周期下降约2%;木质林产品总碳储量随着时间的延长呈逐渐增加的趋势.木质林产品的各个碳库按照碳储量的大小排序为:长期填埋场>长期产品>垃圾场>中期产品>能量(薪材)>短期产品.(3)华北落叶松人工林在林分初期表现为碳源,约5年后成为碳汇,其后大部分时间(约5-45年)表现为碳汇,在林分后期(约46-50年)表现为较强的碳源.从年平均净碳平衡来看,华北落叶松人工林在成林后是一个明显的碳汇,年平均净碳平衡在1.0 t?hm-2左右.(4)在研究地区,天然杨桦次生林转化为华北落叶松人工林的一个轮伐期内(50年),每公顷华北落叶松人工林共约截存250吨碳,约70%的碳通过凋落物和采伐剩余物的方式进入土壤,其余30%进入木质林产品加工制造使用过程.森林截存碳的70%进入土壤碳库,轮伐期结束后,共有约相当于森林截存碳71%的碳通过土壤呼吸释放到大气中,土壤成为大气的一个轻微的碳源.森林截存碳的30%进入木质林产品碳库,轮伐期结束后,约11%储存在林产品碳库中,19%通过林产品分解和能量燃烧的方式回归大气.轮伐期结束后,生物碳储量约为零,林产品碳储量约为27吨,土壤碳储量比造林前减少约2吨.(5)30年、40年、50年、60年、70年轮伐期下华北落叶松人工林的总碳储量都在180 t?hm-2左右,没有明显的差异,但是不同轮伐期下总碳贮量在各碳库中的分配有较明显的差异.轮伐期加长有助于生物碳储量的增加,而林产品碳库与此相反,缩短轮伐期有助于林产品碳的积累.土壤碳储量适宜的轮伐期长度大约为50年,过短或过长都不利于土壤碳库的积累.综合来看,40年是最适宜的轮伐期长度,最有利于碳的储存.但是如果考虑到造林、采伐过程中的碳释放和大径材林产品的使用,长轮伐期可能更利于人工林发挥固碳效益.(6)华北落叶松人工林土壤碳储量随温度升高呈下降趋势,土壤呼吸随温度升高而增强.土壤碳储量随降水增加而下降,土壤呼吸随降水增加而增加.由于气候变化引起的温度上升、降水增加,进而导致土壤呼吸增强、土壤碳储量降低的问题值得关注.
英文摘要: China has the world's largest plantation which played an important role in absorbing CO2. The carbon sink function of plantation is a dynamic process, and which are effected by intermediate cutting and rotation. A comprehensive understanding of the carbon sink function in plantation and its dynamic change process has important scientific and realistic significance. In this paper, biomass carbon, soil carbon, woody forest products carbon and carbon dynamic of the larch plantation in north region of Yanshan mountain were studied. CO2FIX V.2 model was used to simulate carbon dynamic process of larch plantation in different rotations. At the same time, we also studied the effects of rotation, temperature and rainfall on carbon dynamic of the plantation. The main results are as follow:(1) Under the current rotation system in Chengde region, total carbon storage of larch plantation presents periodic changes, ranged from 150 to 200 t?hm-2 in a 50 years rotation. In each cycle, the total carbon storage showed a"reduce-increase-reduce"trend. The contribution rates of soil carbon storage, biomass carbon storage and woody forest products carbon storage to the total were 77%, 17% and 6% respectively. But in different periods of the stands, the rates showed some differences.(2) Biomass carbon storage of the larch plantation presents periodic changes along time, ranged from 0 to 55 t?hm-2. In each cycle, biomass carbon storage show a fluctuant trend. Soil carbon storage varied almost the same in one cycle, i.e. first reduce, then increase fluctuantly and last return to the initial level, the value ranged from 130 to 160 t?hm-2. Carbon storage of woody forest products is gradually increasing with the extension of time. According to the carbon storage value of different woody forest products carbon pools, the order is: long-term landfill > long-term products > dump > mid-term products > energy (firewood) > short-term products.(3) In the early stage of the stand, larch plantation was carbon source, then became carbon sink between 5 to 45 years. But in its later stage (about 46-50 a), the stand became carbon source again. From the annual net carbon balance point of view, larch plantation was obviously carbon source, annual net carbon balance was about 1.0 t?hm-2.(4) In this region, in a 50 years rotation from secondary poplar-birch forest to larch plantation, 250t?hm-2 carbon were sequestrated by the larch plantation. 70% of the carbon transfered into soil through the way of litter and logging slash, the other 30% transfered into woody forest products. After the rotation, about 71%( according to the forest carbon sequestration) of the carbon released to the atmosphere through soil respiration, so that made the soil become a carbon source. And 11% of the carbon stored in the woody forest products, 19% released to the atmosphere through decomposition and energy burning. Then, the values are respectively as follow: biomass carbon storage 0t, woody forest products carbon storage 27t, soil carbon storage reduced about 2t than beginning.(5) With different rotation ( 30 years, 40 years, 50 years, 60 years and 70 years ), the total carbon storage of larch plantation showed no obvious differences, is always about 180 t?hm-2, but the distribution in the three carbon pools has significant difference. Extension of rotation contribute to the increase of biomass carbon storage, whereas short rotation is helpful to the carbon accumulation in woody forest products. Appropriate rotation length of soil carbon storage is about 50 years, but 40 years is the most suitable length to carbon stock in the whole stands. If we considered carbon emission from afforestation, cutting and the use of big-diameter timber products, long rotation is more favorable.(6) When temperature increased, soil carbon storage of the larch plantation would decrease while soil respiration enhanced. When rainfall increased, soil carbon storage decreased and soil respiration enhanced. The increase of temperature and rainfall caused by climate change induced soil respiration enhancement and soil carbon storage decrease. We should pay more attention to these problems.