【作者】 高述超；

【导师】 田大伦；

【作者基本信息】 中南林业科技大学 ， 生态学， 2010， 博士

【摘要】 城市是人口主要集中居住的地区,是人类活动的重要场所,近年来随着城市的功能和规模不断扩大,城市环境污染日益严重,阻碍了社会、经济的发展。而城市森林被称为“城市之肺”,在改善城市地域内的生态环境,促进人与自然协调,满足社会持续发展等方面的作用突出,因此对城市森林的研究正日益受到世界各国的重视,城市森林显著的生态功能也备受各界科学工作者的关注。本研究在长沙城市选择樟树、马尾松人工混交林,对林分土壤理化性质、生物量结构特征、林分生产力、养分循环及生态系统碳素贮量及碳平衡等进行了系统研究。主要研究结果为：1.林地土壤pH值为4.69,属酸性土壤；自然含水量为21.77%；总孔隙度为44.59%；有机质含量为17.59 g·kg-1；全N含量0.99 g·kg-1；全P含量1.13 g·kg-1,且N素、P素有效率低,仅为2%；全K含量6.13 g·kg-1,属于低水平,速效K含量150.15 mg·kg-1,属适量K型土壤；全Ca含量0.79 g·kg-1,全Mg含量3.00 g·kg-1,均为低含量。微量元素含量以Fe最高,为60797 mg·kg-1,Cd最低,仅为1.18mg·kg-1,微量元素含量高低依次排序为：Fe>Mn>Zn>Cu>Pb>Ni>Co>Cd,并呈现Mn被淋溶而向土壤下层迁移,Cu、Fe、Zn、Cd、Ni、Pb、Co在土壤中的积累和淋溶作用不明显的规律。2.森林生态系统中,樟树单株生物量为191.12 kg,马尾松为291.97kg,山矾为29.37 kg,对蕚山矾为18.04 kg。4个树种单株生物量均为树干最高,且显著高于树皮、树枝、树叶和树根(p<0.05)。按林木各器官生物量大小依次顺序,樟树为树干>树根>树枝>树皮>树叶；马尾松、山矾和对蕚山矾则为树干>树枝>树根>树叶>树皮。在同一生态环境条件下,林冠层常绿阔叶速生樟树和常绿针叶速生马尾松均为24年生,而马尾松单株生物量比樟树大1.5倍；下木层山矾与对蕚山矾均为20年生的常绿阔叶树种,山矾单株生物量大于对蕚山矾1.6倍。表明林木个体生物量大小是由其生物学特性决定的,而环境的影响则是次要的。林分乔木层生物量为76.14 t·hm-2,其中樟树为28.67 t·hm-2,占乔木层生物量37.7%；马尾松为17.51 t·hm-2,占23.0%；山矾22.91 t·hm-2,占30.0%；对蕚山矾7.05 t·hm2,占9.3%。灌木层生物量为16.15 t·hm-2,其中木姜子1.47 t·hm-2,黄栀子0.64t·hm-2,幼树14.04 t·hm-2。草木层生物量为0.22 t·hm-2,其中狗脊蕨0.15 t·hm-2,凤尾蕨0.03t·hm-2,棕叶芦0.04 t·hm-2。层外层生物量为0.05 t·hm-2,其中菝葜0.02 t·hm-2,鸡矢藤为0.03t·hm-2。死地被物层生物量为5.00 t·hm-2,其中未分解(L)层为0.53 t·hm2,半分解(F)层为2.57 t·hm-2,已分解(H)层为1.90 t·hm-2。林内年凋落物生物量为7601.66 kg·hm-2·a-1；其中凋落针叶量为3541.22 kg·hm-2·a-1,凋落阔叶1878.20 kg·hm-2·a-1,落果796.67kg·hm-2·a-1,有机碎屑1385.57 kg·hm-2·a-1。林分乔木层生产力为4.85 t·hm-2·a-1,其中樟树为2.62 t·hm-2·a-1,马尾松0.73 t·hm-2·a-1,山矾1.14 t·hm-2·a-1,对蕚山矾0.36 t·hm-2·a-1。3.乔木层四个树种体内大量营养元素平均含量：N为5.92—8.25g.kg-1,P 0.43—0.58 g·kg-1；K 1.50—2.53 g·kg-1,Ca 4.36—10.21 g·kg-1, Mg 0.84—1.10 g·kg-1；微量元素平均含量：Fe 165.90—344.56 mg·kg-1, Cu 7.53—9.00 mg·kg-1,Zn 21.63—41.49 mg·kg-1,Mn 138.78—619.27 mg·kg-1,Cd 0.46—2.25 mg·kg-1；Ni 2.88—3.83 mg·kg-1；Pb 5.70—13.65 mg·kg-1.生态系统中营养元素的总贮量为1423.44 kg·hm-1,存留量为132.07kg·hm-2·a-1,归还量为238.97 kg·hm-2·a-1,吸收量为371.04 kg·hm-2·a-1,利用系数为0.26,循环系数为0.64,周转时间为5.96年。樟树、马尾松混交林生态系统,养分归还速率快,循环强度大,利用率高,周转时间不长,有利于生态系统和林地养分的维持。4.乔木层各树种的平均碳素含量樟树为539.73 g·kg-1,马尾松为458.40 g·kg-1,山矾470.13 g·kg-1,对蕚山矾463.50 g·kg-1。樟树各器官碳素含量差异不显著(p>0.05),马尾松各器官碳素含量差异显著(p<0.05),山矾叶碳素含量显著低于树干和树枝(p<0.05)；对蕚山矾树干和树皮碳素含量显著高于树叶(p<0.05)。林下灌木层植物碳素平均含量以木姜子最高为481.47 g·kg-1,其次为黄栀子452.81 g·kg-1,再次为幼树466.67 g·kg-1。草本植物碳素平均含量棕叶芦为475.55 g·kg-1,凤尾蕨422.71 g·kg-1,狗脊蕨396.04 g·kg-1。藤本植物碳素平均含量菝葜为470.36 g·kg-1,鸡矢藤437.69 g·kg-1。草本植物和藤本植物地上部分茎叶碳素含量均高于地下部分根系。死地被物层的碳素含量,未分解L层为401.80 g·kg-1,半分解F层为436.59 g·kg-1,已分解H层为352.72 g·kg-1。凋落物层碳素含量：凋落针叶为325.03 g·kg-1,阔叶360.75 g·kg-1,落果425.18 g·kg-1,有机碎屑461.80 g·kg-1。林地土壤0-60cm层碳素平均含量为10.20 g·kg-1,并随土层的增加而逐渐下降。5.生态系统碳素的贮量为132.68 t·hm-2,其中乔木层为38.52 t·hm-2,灌木层为7.27 t·hm-2,草本层0.09 t·hm-2,层外层0.02 t·hm-2。死地被物层2.00 t·hm-2,土壤层(0-60cm)84.78 t·hm-2。系统中碳素贮量高低依次排序为土壤层>植被层>死地被物层。6.林分乔木层年净固定碳量为2.44 t·hm-2·a-1,其中樟树为1.37t·hm-2·a-1,马尾松0.35 t·hm-2·a-1,山矾0.54 t·hm-2·a-1,对蕚山矾0.18·hm-2·a-1。凋落物固碳量为2.81 t·hm-2·a-1,其中凋落针叶固碳量为1.15t·hm-2·a-1,阔叶0.68 t·hm-2·a-1,落果0.34 t·hm-2·a-1,有机碎屑0.64t·hm-2·a-1;土壤呼吸量(非根呼吸量)为3.58 t·hm-2·a-1。长沙城市樟树马尾松人工林生态系统碳收支平衡为正值,即生态系统与大气碳的交换中表现为碳汇,碳汇量为1.67 t·hm-2·a-1。更多还原

【Abstract】 A city is a large and densely populated urban area and is where human activities intensively taken place. With the growth of urban population and urbanization, many environmental problems are associated with urban development. Problems such as air pollution, biological and environmental degradation, and fresh-water supply shortage have become a growing concern increasing over the years. The Urban forests, called the "lungs of the city", play an important role in improving urban environment quality, regulating the relations between nature and human, and supporting sustainable development in urbanization. As a consequence, a great deal of efforts has been made to investigate structure, function and ecosystem services of urban forests around the world. In this study, physical and chemical properties of soil, patterns of stand biomass and productivity, nutrient biological cycle process, and carbon storage capacity in Camphor tree (Cinnamomum camphora (L.) Presl) and Masson pine(Pinus massoniana Lamb) mix-forest ecosystems were investigated in Changsha city, Hunan province. The results showed as following:1. The soils in the studied forests were acidic with a mean pH scale of 4.7. Soil water content averaged 21.8% and total soil porosity was 44.6%. Soil organic matter content was 17.59 g·kg-1. The concentration of total nitrogen (N) and phosphate (P) in soils was 0.99 and 1.13 g·kg-1, respectively. Both available-N and available-P contents were relatively low and accounted for around 2% of the total N and P in the study sites. The concentration of potassium (K) was low (6.13 g·kg-1) but available-K content was in adequate level (150.15 mg·kg-1). The concentration of Calcium (Ca) and Magnesium (Mg) in soils was 0.79 and 3.00 g·kg-1, which was relative low.The concentrations of micronutrients in soils were in an order as Fe> Mn> Zn> Cu> Pb> Ni> Co> Cd, with the highest in Fe (60797 mg·kg-1) and lowest in Cd (1.18 mg·kg-1). It was found that Mn was obviously transferred down along soil profiled due to leaching process. No apparent patterns were found for micronutrient elements, Cu, Fe, Zn, Cd, Ni, Pb and Co in terms of accumulation and leaching in soils.2. Mean biomass of an individual tree was 191.1,292.0,29.4, and 18.0 kg in the four tree species, Camphor tree, Masson pine, Symplocos sumuntia and Symplocos anomala in the studied mix-forests. Biomass was highest in stem organ, and was significantly higher than that in bark, branch, leaves and root (p<0.05). Biomass was in an order:stem> root> branch> leaves> bark in tree species Camphor tree, but was in an order as stem> branch> root> leaves> bark in Masson pine, Symplocos sumuntia and Symplocos anomala. Under the similar habitat, there was a significant difference of biomass production for different tree species even they were in the same age. For example, mean biomass of an individual tree in a 22-year old Masson pine was 1.5 time as high as that in a 22-year old Camphor tree, and mean tree biomass of a 20-year old Symplocos sumuntia was 1.6 times higher than that in a 20-year old Symplocos anomala. The results indicated that biomass production of an individual tree was primarily determined by biological features of the tree species, and environmental variables were the second most important factors in controlling biomass production.Stand biomass of overstorey in the forests was 76.14 t-hm-2, of which Camphor tree was 28.67 t·hm-2, accounting for 37.7%; Masson pine was 17.51 t·hm-2, accounting for 23.0%; Symplocos sumuntia was 22.91 t·hm-2, accounting for 30.0%, and Symplocos anomala was 7.05 t·hm-2, accounting for 9.3% of the total biomass in overstorey.Biomass in shrub layer was 16.15 t·hm-2, of which Neolitsea aurata was 1.47 t·hm-2, Gardenla Jasminoides was 0.64 t·hm-2, and other seedlings was 14.04 t·hm-2.Biomass in herbivorous layer was 0.22 t·hm-2, of which Woodwardia japonica was 0.15 t·hm-2, Spider brake (Pteris multifida Poir) was 0.03 t·hm-2 and Thysanolaena maxima was 0.04 t·hm-2.Biomass in lianas layer was 0.05 t·hm-2, of which Smilax china was 0.02 t·hm-2 and Paederia scandens was 0.03 t·hm-2. Biomass in dead floor layer was 5.00 t·hm-2, of which non-decomposed part (L) was 0.53 t·hm-2, semi-decomposed part (F) was 2.57 t·hm-2 and decomposed part (H) was 1.90 t·hm-2.Annual amount of litter-fall in the forests was 7601.66 kg·hm-2·a-1, of which litter-needle was 3541.22 kg·hm-2·a-1, litter-broad-leaves was 1878.20 kg·hm-2·a-1, litter-fruit was 796.67 kg·hm-2·a-1 and litter-organic debris was 1385.57 kg·hm-2·a-1.Stand productivity in overstorey in the mix-forests was 4.85 t·hm-2·a-of which Camphor tree was 2.62 t·hm-2·a-1, Masson pine 0.73 t·hm-2·a-Symplocos sumuntia 1.14 t·hm-2·a-1 and Symplocos anomala 0.36 t·hm-2·a-1.3. Mean concentration of macronutrient elements in the four tree species was:N was 5.92-8.25 g·kg-1, P 0.43-0.58 g·kg-1, K 1.50-2.53 g·kg-1, Ca 4.36-10.21 g·kg-1 and Mg 0.84-1.10 g·kg-1. Concentration of micronutrient elements ranged as:Fe 165.90-344.56 mg·kg-1, Cu 7.53-9.00 mg·kg-1, Zn 21.63-41.49 mg·kg-1, Mn 138.78-619.27 mg·kg-Cd 0.46-2.25 mg·kg-1, Ni 2.88-3.83 mg·kg-1 and Pb 5.70-13.65 mg·kg-1.The total storage of nutrients in the mix-forest ecosystems was 1423.44 kg·hm-2. Annual retention amount was 132.07 kg·hm-2·a-1, annual return amount was 238.97 kg·hm-2·a-1 and annual uptake amount was 371.04 kg·hm-2·a-1. The utilization coefficient (retention/uptake) was 0.36, cycling coefficient (return/uptake) was 0.64, and turnover time was about 6 years. The results suggested that the Camphor tree and Masson pine mix-forest ecosystems were characterized by fast return rate, high cycling intensity, high utilization efficiency and relative short turnover time in terms of nutrient biological cycle. These features provide benefits for the forest ecosystems in maintaining site fertility.4. Average carbon content in overstorey in the mix-forests was: Camphor tree 539.73 g·kg-1, Masson pine 458.40 g·kg-1, Symplocos sumuntia 470.13 g·kg-1 and Symplocos anomala 463.50 g·kg-1. Carbon content in different organs did not significantly differ in Camphor tree (p>0.05), but was considerably different in Masson pine (p<0.05). Carbon content was statistically lower in leaves than in stem and branch in Symplocos sumuntia (p<0.05), and was considerably higher in stem and bark than in leaves in Symplocos anomala (p<0.05).It was found that Neolitsea aurata had the highest carbon concentration (481.47 g-kg-1) in shrub layer, the next was Gardenla Jasminoides (452.81 g·kg-1) and other seedlings (466.67 g·kg-1).Mean carbon concentration in the herbivorous layer was:Woodwardia japonica 475.55 g·kg-1, Spider brake (Pteris multifida Poir) 422.71 g·kg-1 and Thysanolaena maxima 396.04 g·kg-1Carbon content in lianas layer was:Smilax china 470.36 g·kg-1 and Paederia scandens 437.69 g·kg-1. Carbon content was higher in shoot than in root in both herbivorous and lianas layers.Carbon content in dead floor layer was:non-decomposed part (L) 401.80 g·kg-1, semi-decomposed part (F) 436.59 g·kg-1 and decomposed part (H) 352.72 g·kg-Carbon content in litter-fall layer was:litter-needle 325.03 g·kg-1, litter-broad-leaves 360.75 g·kg-1 litter-fruit 425.18 g·kg-1 and litter-organic debris 461.80 g·kg-1.Carbon content in soils (60 cm depth) was 10.20 g·kg-1, and was decreased with increasing of soil depth.5. Total carbon storage in the forest ecosystems was 132.68 t·hm-2, of which overstorey layer was 38.52 t·hm-2, shrub layer was 7.27 t·hm-2, herbivorous layer was 0.09 t·hm-2, lianas layer was 0.02 t·hm-2, dead floor layer was 2.00 t·hm-2 and soil layer (0-60cm) was 84.78 t·hm-2. Carbon storage in different compartments of the ecosystems was in an order:soil vegetation> dead floor layer.6. Annual carbon sequestration in overstory layer was 2.44 t·hm-2·a-1, of which Camphor tree was 1.37 t·hm-2·a-1, Masson pine 0.35 t·hm-2·a-1, Symplocos sumuntia 0.54 t·hm-2·a-1 and Symplocos anomala 0.18 t·hm-2·a-1.Annual carbon stored in litter-fall was 2.81 t·hm-2·a-1, of which litter-needle was 1.15 t·hm-2·a-1, litter-broad-leaves 0.68 t·hm-2·a-1, litter-fruit 0.34 t·hm-2·a-1 and litter-organic debris 0.64 t·hm-2·a-1. Soil respiration (exclude root respiration) was 3.58 t·hm-2·a-1. Net ecosystem productivity was 1.67 t·hm-2·a-1 in the Camphor tree and Masson pine mix-forest ecosystems in Changsha city. Our results indicated that the Camphor tree and Masson pine urban forests was a carbon sink.更多还原