上海城市森林多尺度生态质量评价研究

发布时间：2018-01-04 19:02

本文关键词：上海城市森林多尺度生态质量评价研究　出处：《华东师范大学》2017年博士论文　论文类型：学位论文

【摘要】：城市森林作为重要的城市绿色基础设施和生态系统的重要组成部分,在改善城市生态环境、保护生物多样性、提高城市综合竞争力方面,具有无法替代的地位。快速城市化背景下,从不同尺度对城市森林结构和功能进行多维度生态质量系统研究及评估,并诊断其制约因素,提出应对措施,将有利于构建布局合理、结构健全、功能高效的城市森林。本研究以上海市域为研究区域,城市森林为研究对象,在分析森林斑块空间分布格局的基础上,通过对全市201个城市森林样点,816个样方进行群落学调查,测算主要物种的三维绿色体积绿量、叶面积指数、生物量及净增生物量等物质生产相关功能,旨在从景观、群落和个体水平上揭示上海城市森林结构和功能现状及空间差异,阐明其主要环境影响因素及结构和功能之间的耦合关系;并据此对上海城市森林在景观空间布局、物种组成、群落结构和生态功能多个维度上进行了问题诊断和生态质量综合评价,探讨低效城市森林的恢复途径和重建方法,以期为上海城市森林后续建设和改造提供理论基础和实践参考。主要结论如下:(1)上海城市森林空间分布格局基于2015年8月遥感影像和2014年上海森林资源分布图,对上海森林斑块信息进行提取和解译,并分析其景观空间格局,结果表明:上海城市森林主要以巨型斑块和大型斑块分布为主;城乡梯度上,森林面积总量呈现出远郊近郊中心城区的格局,但森林覆盖率近郊优于远郊和中心城区;景观尺度上,不管从景观构成还是景观指数方面看,上海城市森林景观生态质量均低下,存在破碎化程度较高、景观连接度较差、景观斑块边界整齐单一、斑块间生态过程联系较弱等问题。(2)上海城市森林物种组成与群落类型基于201个样地和816个样方的调查,共记录维管植物126科405属567种,其中原生种246种,占总种数的43.4%;外来种仅22种,且21种为草本植物。不同生活型间,草本植物种数最多,为250种;常绿阔叶乔木虽仅占总种数的5.8%(33种),但累计频率高达14.4%,尤以香樟(Cinanamomum camphora)和女贞(Ligustrum lucidum)累计频率最高。上海城市森林群落类型丰富,从森林起源和人为干扰影响角度,归属于自然次生林、近自然林、人工次生林和人工林4大森林类型;其中以常绿阔叶林、常绿落叶阔叶混交林和落叶阔叶林为主,常绿阔叶林群落类型较少,但少数群落类型,如香樟群落,分布面积很广;人工林中群落类型丰富,但缺少在自然次生林中常见的群落类型,如青冈(Cyclobalanopsis glauca)群落等。(3)上海城市森林群落结构特征上海城市森林群落物种丰富度较高,丰富度为1-2种和3-5种的分别占10%,6种以上的占80%,其中6-10种的占27.2%,11-15种的占25.1%,15-20种占15.7%,20种以上的占12.8%;将森林群落中的植物归类后发现,原生种的丰富度栽培种和栽培逸生种外来种;将森林按垂直结构划分后,乔木层、大灌层、小灌层和草本层丰富度分别为2.49、3.46、3.66和7.64;按森林类型划分,近自然林的丰富度人工次生林自然次生林人工林,人工林丰富度指数显著低于前三者;在城乡梯度上,群落内原生种丰富度由中心城区至远郊逐渐增加。上海城市森林整体群落垂直结构较为完整,以复层性结构为主;但近郊、人工林和防护绿地中乔灌草结构比例显著低于其他类型,且以纯林为主。总体上,木本植物胸径介于7～25 cm之间,属于中幼林;近郊、人工林和防护绿地的胸径变异系数和高度变异系数显著低于其他类型。近22%的人工林个体密度偏高,而其他森林类型均处于适宜水平。本研究中71.7%样方其林下有木本植物更新个体,分属于54科102属124种,占林木层总物种数的40.3%;其中混交林和垂直结构丰富的群落中更新物种较丰富。自然次生林中占优势的糙叶树(Aphananthe aspera)、青冈、红楠(Machilus thunbergii)等物种在人工林中较为少见,表明种源是限制林下自然更新的重要因素;此外,CCA分析表明土壤pH、容重、有机质含量及乔木层盖度,是影响更新层物种组成的环境因素。(4)上海城市森林物质生产功能上海城市森林单位面积三维绿色体积绿量为5.79m3/m2,叶面积指数(LAI)平均为35.89,单位面积生物量和单位面积年净增生物量分别为13.02kg/m2和1.75kg/m2/a;具有复层垂直结构的森林群落其4个指标均大于垂直结构简单的群落。人工次生林在叶面积指数、单位面积生物量和单位面积净生物量3个指标方面均为最高,自然次生林的单位面积体积绿量为最高。在城乡梯度上,四个指标均为中心城区远郊近郊,反映了城市环境梯度和群落结构城乡差异的综合影响。上海城市森林常见物种的物质生产功能存在种间差异,4个指标均为乔木灌木草本、针叶树阔叶树、原生种外来种。此外,物质生产功能在种内存在差异,并主要受其所在地群落结构和环境因子的影响:LAI、净生物量(ABM)分别与个体密度、林冠层郁闭度呈显著负相关;落叶树种相较于常绿树种,对环境变化更为敏感,其LAI和ABM与大气污染指标,如PM_(2.5)、SO_2、NO_2有显著关联,且与土壤土壤容重正相关、与土壤有机质负相关。(5)上海城市森林生态质量诊断选取上述研究中相关指标,采用主客观赋权法,构建上海城市森林生态质量综合评价体系,包括2个次目标层,其中近自然度目标层包括5个准则层、共35个指标,景观结构目标层包括2个准则层、共8个指标;运用该评价体系对上海城市森林生态质量进行评估,结果表明:基于景观-群落尺度,上海城市森林生态质量总体低下,以中心城区最低,黄浦区最差,崇明区和松江区较好。基于群落尺度,近自然度综合评价值介于0.092～0.616,平均值为0.374,整体处于近自然度Ⅲ级,即中度低效水平,其中混交林显著高于其他群落类型,垂直结构丰富的群落高于垂直结构单一的群落;城乡梯度上,近郊显著低于远郊和中心城区;人工林显著低于自然次生林、近自然林、人工次生林3种森林类型;防护林显著低于其他绿地类型;按照近自然度综合评价值的划分标准,自然次生林在近自然度V级(良好)以上高达87.5%,因而可以选择自然次生林作为上海低效人工林近自然恢复的参照系。(6)低效森林生态恢复对策与途径基于上海城市森林近自然度综合评价的结果,针对低效森林存在的问题,提出了生态恢复对策与途径:首先综合自然区划、森林生态敏感程度以及主导功能定位、环境质量等因素,划分若干生态恢复单元,并基于各生态恢复单元森林的近自然度等级,确定恢复目标;其次,低效森林恢复改造应兼顾"适生境适群落"和"适功能适群落"两个原则,不同生态恢复单元选择适宜性植物种类和群落类型;此外,低效森林恢复改造宜结合多种技术,包括土壤修复技术和抚育间伐、封育补植和更新改造等森林管理措施。
[Abstract]:City forest as an important part of the important city of green infrastructure and ecological system, in improving the city's ecological environment, protecting biodiversity, improve the city's comprehensive competitiveness, has an irreplaceable position. Under the background of Rapid City, from different scales of assessment and multi dimension of ecological quality system on the structure and function of city forest the diagnosis, and its restricting factors, put forward the corresponding measures, will be conducive to building a reasonable layout, structure and improve the efficient function of the city forest. This study takes Shanghai city as the study area, city forest as the research object, based on the analysis of forest spatial distribution pattern, the 201 city city forest sample 816 plots, community survey, three-dimensional green green volume calculation of main species, leaf area index, biomass and net biomass material production function, purpose In the landscape, reveal the differences of status and spatial forest structure and function of Shanghai city community and individual level, the coupling relationship between the main environmental impact factors and the structure and function; and the Shanghai city forest landscape spatial distribution, species composition, community structure and ecological function of multiple dimensions of comprehensive evaluation diagnosis and ecological quality problems, to explore ways to restore and rebuild the inefficient forest city, in order to provide theoretical basis and practical reference for the Shanghai city forest construction and subsequent transformation. The main conclusions are as follows: (1) on forest spatial distribution in Haicheng city based on remote sensing image distribution pattern in August 2015 and 2014 of Shanghai forest resources, forest patches in Shanghai information extraction and interpretation, and analysis of the landscape spatial pattern, the results show that the Shanghai city forest mainly in large patches and large plaque distribution; The urban-rural gradient, the total forest area showing the outer suburb suburban city center pattern, but the forest coverage rate is better than that of suburban suburban and urban centres; the landscape scale, regardless of the landscape or landscape index, Shanghai city forest landscape ecological quality is low, higher deposit in the degree of fragmentation, landscape connectivity is poor, landscape patch boundary in a single, ecological relation is weak and other issues between patches. (2) Shanghai city forest species composition and community types based on the investigation of 201 sample plots and 816 plots were recorded, 126 families of vascular plants in 405 genera and 567 species, including 246 species of native species, accounting for 43.4% of the total species; only 22 species of alien species and, 21 kinds of herbs. Different types of life, herb species 250; 5.8% evergreen broad-leaved trees was only the total species (33 species), but the cumulative frequency of up to 14.4%, especially in the camphor (Cinanamomum and camphora) Privet (Ligustrum lucidum) has the highest frequency. Shanghai city forest community types, from the point of origin of forest and man-made interference, attributable to natural secondary forest, near natural forest, 4 forest types of artificial forest and artificial forest; evergreen broad-leaved forest, evergreen and deciduous broad-leaved mixed forest and deciduous broad-leaved forest, evergreen broad-leaved forest types the community is less, but a small number of community types, such as camphor community, a very wide distribution area; artificial forest community type is rich, but the lack of community types common in natural secondary forests, such as beech (Cyclobalanopsis glauca) community. (3) Shanghai city forest community structure of forest communities in Shanghai city the higher species richness, richness of 1-2 and an 3-5 accounted for 10%, more than 6 kinds of 6-10 accounted for 80%, which accounted for 27.2%, 11-15 accounted for 25.1%, 15-20 accounted for 15.7%, more than 20 accounted for 12.8%; the forest community The plant classification showed that native species richness of cultivated and naturalized species cultivated exotic species; the forest by the vertical structure into tree layer, shrub layer, large, small shrub layer and herb layer were 2.49,3.46,3.66 and 7.64 respectively; divided by forest types, near natural forest the abundance of artificial secondary forest natural forest artificial forest, plantation species richness index was significantly lower than that of the former three; in the urban and rural gradient, native species richness increased gradually in the community from the city center to the suburb of Shanghai city. The whole forest community vertical structure is complete, with double layer structure; but the suburbs, grass and shrub structure proportion of plantation and protective greenbelt was significantly lower than that of YISHION and other types of forest. On the whole, DBH between woody plants 7 ~ 25 cm, belonging to the young; the suburbs, DBH variation coefficient of plantation and protective green and high coefficient of variation was significantly lower than that of Other types of artificial forests. The individual density high of nearly 22%, while other forest types were in the appropriate level. There are woody plants in this study, 71.7% individuals to update the forest plots, belonging to 54 families and 102 genera and 124 species, accounting for the total property of tree layer species of 40.3%; the renewal of mixed forest and rich community vertical structure the species are abundant. Aphananthe advantage in natural secondary forest (Aphananthe aspera), Cyclobalanopsis, Machilus (Machilus thunbergii) and other species is rare in plantation, that kind of source is an important limiting factor of forest natural regeneration; in addition, CCA analysis showed that soil pH, bulk density, organic matter content and tree layer coverage, is the environmental factors affecting the regeneration layer species composition. (4) Shanghai city forest material production function of Shanghai city forest unit area three-dimensional green green volume was 5.79m3/m2, the leaf area index (LAI) averaged 35.89, biomass per unit area Unit area and net biomass was 13.02kg/m2 and 1.75kg/m2/a respectively; with complex forest community vertical structure of the 4 layer were greater than that of the vertical structure of simple artificial secondary forest communities. The leaf area index, net biomass per unit area biomass per unit area and 3 side index were the highest, the volume of unit green area the natural secondary forest was the highest. In the urban-rural gradient, four indexes as the center of the city's outer suburbs, reflects the combined effects of different city environmental gradient and community structure in urban and rural areas. The material production work of Shanghai city forest common species can exist among species, 4 indexes of trees and shrubs and herbs, conifer broadleaf trees, native exotics. In addition, the material production function in memory in the difference, which is mainly affected by the local community structure and environmental factors: LAI, net biomass (ABM) respectively with a volume density of forest The canopy density was negatively correlated; deciduous trees compared to evergreen tree species, are more sensitive to environmental change, the LAI and ABM and air pollution index, such as PM_ (2.5), SO_2 had a significant correlation with NO_2, and positively correlated with soil bulk density, and negatively with soil organic matter (5) in Shanghai city. Forest ecological quality diagnosis, select the relevant indicators in the study, the subjective and objective weighting method to construct the comprehensive evaluation system of forest ecological quality of Shanghai City, including 2 sub target layer, the naturalness of the target layer includes 5 criterion layers, a total of 35 indicators, the landscape structure target layer includes 2 criterion layers, a total of 8 by using the evaluation indicators; evaluation system of forest ecological quality in Shanghai City, the results showed that: Landscape - community scale based on Shanghai city forest ecological quality is generally low, the central city of Huangpu District is the worst, the lowest, Chongming district and Songjiang District based on the community better. The scale and naturalness of the comprehensive evaluation value from 0.092 to 0.616, with an average of 0.374, in the naturalness of grade III, which is moderately low level, which was significantly higher than other mixed forest community types, the vertical structure of community is higher than that of single rich community vertical structure; urban-rural gradient, suburban and urban centres were significantly lower than that of outer suburbs; plantation was significantly lower than that of natural secondary forest, near natural forest, artificial forest 3 forest types; protection forest was significantly lower than other types of green space; in accordance with the standards of comprehensive evaluation of near natural value, the natural secondary forest in the naturalness of class V (good) or as high as 87.5%, it can be used as a Shanghai plantation near natural recovery efficiency the reference system of natural secondary forest. (6) the inefficient Forest Ecological Restoration Countermeasures and ways of Shanghai city forest naturalness evaluation based on the results, aiming at the existing problems of inefficient forest. The ecological restoration measures and approaches: the first comprehensive natural zoning, forest ecological sensitivity and leading function, quality and other environmental factors, divided into several ecological restoration unit, based on close to nature forest restoration the ecological unit level, the objective of recovering; secondly, inefficient forest restoration and reconstruction should be "suitable habitat and community" "fitness function community" two principles, choose suitable types of different ecological restoration unit of plant species and communities; in addition, inefficient forest restoration and reconstruction should be combined with a variety of techniques, including soil remediation and thinning, fencing and replanting and renewal of forest management measures.

【学位授予单位】：华东师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S718.5

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