【作者】 温家石；

【导师】 常杰； 葛滢；

【作者基本信息】 浙江大学 ， 生态学， 2010， 硕士

【摘要】 城市化引起的土地利用和土地覆盖的变化极大地改变了生态系统过程和功能,已经成为生态学研究的热点。城市化区域的碳循环,特别是建成区植被的碳吸收和碳储存能力数据的缺乏已成为研究地区乃至全球碳循环的瓶颈。目前在城市区域关于碳吸收和碳储存的研究发现:一方面,城市中的不透水层降低了植被覆盖率,造成建成区单位面积碳的吸收和储存能力降低;另一方面,人工管理、热岛效应和相对低臭氧等可能使单株树木生长速度高于野外。植被覆盖的减少和单株生产力的提高这两个相反的驱动力使得城市化地区植被碳吸收能力存在不确定性。本研究构建了适合城市植被的调查研究方法,并选择中国城市化速度最快的东南沿海的两个城市——历史名城杭州和新兴城市台州这作为典型案例,通过实地调查和测量研究了城市植被生长和碳的吸收和储存能力,分析了城市园林管理对交通绿地、公园、学校和居住区绿地等中的乔木、灌丛和草坪的生物量和净初级生产力（NPP）的影响,并将城市土地碳吸收和碳储存能力与野外森林进行了比较。研究发现:1.杭州建成区植被一年固定了132 388.2 tC,其中树木贡献了74%,草坪贡献了24%,灌木贡献了2%。整个建成区的碳吸收能力为4.3 tC·hm^-2·yr^-1。杭州建成区植被总碳储量为554 689.8 tC,其中乔木总碳储量为503 937.0 tC,比灌木（8 857.8 tC）与草坪（41 895.0 tC）之和的十倍还多。台州建成区植被一年固定了23 949.9 tC,其中树木贡献了64%,草坪贡献了27%,灌木贡献了9%。整个建成区的碳吸收能力为2.1tC·hm^-2·yr^-1。台州建成区植被总碳储量为91 763.1 tC,其中乔木总碳储量为66 467.7 tC,比灌木（15 338.7 tC）与草坪（9 956.7 tC）之和的两倍还多。2.由于人类管理和城市环境的共同影响,使得杭州与台州城市树木个体生物量年增量是野外森林中同类树木的近2倍。这说明在湿润亚热带地区城市植被与野外植被生长的差异与其他气候区一致。城市中管理条件下对树木的园林修剪贡献了城市树木NPP的近三分之一,这一发现表明国内外以往的没有考虑园林修剪的研究需要重新估算。3.通过与野外常绿阔叶林比较发现,目前杭州建成区的碳吸收能力已经达到甚至超过了野外常绿阔叶林水平,而台州建成区的碳吸收能力也可以通过提高绿化覆盖率（从23%提高到46%）达到野外常绿阔叶林水平。这一发现为找寻城市“碳中立”的途径打下基础,也为政府和有关规划部门进行未来城市区域碳管理提供决策依据。4.台州市建成区因为年轻,因而树木整体偏小;然而杭州建成区的城市树木也表现出与城市年龄不符的较小树龄,是因为绿化土地的减少和树木频繁更替。因而未来城市的绿化不仅仅需要增加面积和比例,还应该加强对已有绿地,特别是年龄较老的绿化用地的保护。更多还原

【Abstract】 Urbanization is the most important aspect of land use and land cover change globally and dramatically altered the ecosystem process and function.With the increase of scientific and political interest in regional aspects of the global carbon cycle,the missing of inventory data of urban area has already bottleneck the evaluation of regional carbon balance.There are two opposite forces drive the carbon sequestration of the plants within the urban areas.On one hand,urban land use reduced the coverage of vegetation with impervious surface.On the other hand,GS within urban location may have higher productivity than surrounding wildland due to garden management,heat island,ozone restriction etc.Those opposite driving forces leave uncertainty of the net effect of urban land use on regional carbon sequestration variation.Using comprehensive field survey of the distribution and growing conditions of vegetation in the young city-Taizhou and the historical city-Hangzhou in the Southeastern China,our objective was to assessing the carbon sequestration and storage by estimating the biomass and net primary productivity（NPP） of urban vegetation including trees,shrubs and lawns in the greenspace in both streets and parks with the consideration of garden management（pruning and mowing） effect.The annual carbon fixation of vegetation in Hangzhou built-up area is 132 388.2 tC in which trees accounted for about 74%lawn accounted for 24%and shrub only 2 %.The carbon sequestration of Hangzhou built-up area is 4.3 tC·hm^-2·yr^-1 the carbon storage of vegetation in Hangzhou is 554 689.8 tC in which trees contributed 503 937.0 tC,lawn contributed 41 895.0 tC and shrub contributed only 8 857.8 tC.The annual carbon fixation of vegetation in Taizhou built-up area is 23 949.9 tC in which trees accounted for about 64%lawn accounted for 27%and shrub only 9%.The carbon sequestration of Taizhou built-up area is2.1tC·hm^-2·yr^-1 the carbon storage of vegetation in Hangzhou is 91 763.1 tC in which trees contributed 66 467.7 tC,lawn contributed 9956.7 tC and shrub contributed only 15 338.7 tC. We also found that due to the urban environment and human activities effects,the trunk growth rate of individual urban tree is two times of that in the native forest.This shows that urban vegetation is different with wild vegetation is samilar in the humid subtropical regions with the other climatic zones.In urban area,pruning contributes 30%of tree NPP.This means the previous work should revaluate there results.By comparing with natural forest,the carbon sequestration ability of Hangzhou built-up area has already met the level of native evergreen broad-leaved forest and we infer that the carbon sequestration ability of Taizhou built-up area can meet the level of native evergreen broad-leaved forest with green coverage rising from 23%up to 46%.This help government and the planning department to find way to fulfill "carbon neutral" in the future management and decision-making.Taizhou was very young thus the urban trees are quite small.However,because of the reduction of green land and trees by frequent turnover,urban trees in Hangzhou also show smaller ages comparing with the age of the city.Therefore,in the future, urban greening should not only increase the area and proportion,but also should pay more attention to protect the existing green space,especially the old greenspace.更多还原