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波士顿大都会区的情景规划:探索城市未来发展的环境和社会影响 12.31.2013
波士顿大都会区的情景规划:探索城市未来发展的环境和社会影响
Scenario Planning for the Boston Metropolitan Region:
Exploring Environmental and Social Implications of Alternative Futures
撰文:(美国)劳勃 · L. · 莱恩 (美国)佩吉 · S. · 瓦伦 (美国)克雷格 · 妮可森  (中国)郑景文  (美国)瑞秋 · 丹福德  (德国)迈克尔 · 斯特巴赫
翻译:孙帅
Text by Robert L. RYAN(US) Paige S. WARREN(US) Craig NICOLSON(US) ZHENG Jing-wen(CN) Rachel DANFORD(US) and Michael STROHBACH(DE)
Translation by SUN Shuai
摘要:波士顿大都市区城市长期生态研究区(BMA-ULTRA-EX)项目是一个跨学科的项目,正在研究对城市生态系统有影响的社会经济和生物物理领域。波士顿地区正在经历着的城乡结合部的低密度城市扩张(郊区化)对自然资源和环境产生了一定的影响。与此同时,像波士顿这样的中心城市,伴随着商业中心和交通枢纽附近的有限的加密开发(致密),一些低收入社区正在面临着经济的衰落。这些社会经济力量竞争过程中的郊区化、致密化和撤资也对城市生态环境系统产生影响。通过景观规划措施来解决这些问题,需要一个积极主动的做法,将目前建成的土地集中发展,而在边缘郊区保护自然资源,同时在当前高密度的城市核心区增加绿化并提高生态系统服务功能。
通过这种景观规划方法,研究小组利用一个利益相关者驱动的过程,制定出一套4个情景规划方案来探索区域的未来。描述了这个利益相关者参与的规划过程,并进行初步分析,最后,为其他从事情景规划的景观规划师们总结了项目的经验。
关键词:景观规划;城市生态;情景规划
Abstract: The Boston Metropolitan Area Urban Long-term Ecological Research Area (BMA-ULTRA-EX) Project is an interdisciplinary project that is studying the effects of socio-economic and bio-physical drivers on urban ecosystems. The Boston region is experiencing low-density urban sprawl (suburbanization) on the rural-urban fringe that is creating environmental impacts to natural resources. At the same time, central cities such as Boston are seeing disinvestment in some low-income neighborhoods causing property abandonment, along with limited infill development (densification) near the commercial core and transit hubs.  These competing socio-economic forces of suburbanization, densification, and disinvestment have environmental implications for urban ecosystems. Landscape planning initiatives to address these issues will require a pro-active approach to concentrating development on currently built lands and in the suburban fringe to protect natural resources, while greening and enhancing ecosystem services in the current high-density urban core.
It is within this landscape planning setting that the research team used a stakeholder- driven process to develop a set of four planning scenarios to explore the future of the region. This paper will describe the planning process with stakeholders to develop these plans, along with the preliminary analyses.  It will conclude with insights for other landscape planners engaged in scenario planning.
Key words: Landscape Planning; Urban Ecology; Scenario Planning
波士顿大都市区城市长期生态研究区(BMA-ULTRA-EX)项目是一个跨学科的项目,正在研究对城市生态系统有影响的社会经济和生物物理领域。波士顿地区正在经历低密度的城乡边缘区发生郊区城市化的过程,并对那里的自然资源不断增加环境压力。与此同时,像波士顿这样中心城市的低收入社区里,撤资的情况造成财产被遗弃,商业中心和交通枢纽的开发密度受到限制。
郊区化、致密化、撤资等社会经济力量影响着城市生态系统(包括城市森林冠层,水体的数量和质量以及生物多样性)。采用景观规划措施来解决这些问题需要一些积极主动的做法,使得目前建成的和郊区边缘的土地得以集中发展,也可以保护森林、农场和其他自然资源,同时在当前的高密度城市核心区增加绿化并提高生态系统服务功能。
在这个景观规划方案中,研究小组使用了一种利益相关方驱动程序,发展出一套4个探索区域未来发展的规划方案。本文将介绍规划方案的制定过程并进行初步分析,最后阐述了作者的体会和感悟,与其他进行情景规划的景观规划师分享。
1 背景
情景规划是一个独特的工具,可以将未来多种变化进行可视化处理,以便于规划师处理时空变化与多个空间尺度(米耶斯与基特苏,2000)。情景是灵活的并适应未来潜在的多种条件,为处理土地利用总体规划中固有的不确定性提供了一种应对战略(皮特森等,2003;克洛斯特曼,2007;斯泰恩等,2003)。它允许规划者制定基准,说明庞大系统在经济、生态和社会等方面的未来展现出的多种可能性。它促进利益相关者和公众参与到景观规划过程中去,并将不同决定所带来的不同结果展示出来,使规划的过程更加可视和透明(甘德尔, 2008)。
波士顿大都市区的人口约448万,排名全美国第10。但据预测,在未来数十年里将经历适度的人口增长。而城市新的发展主要位于在城乡结合部,预计消耗615 122 176m2空地,其中234 717 672m2为珍稀和濒危物种的栖息地(都市未来规划,2009)。这种城市扩张已经促使规划师努力尝试将新的发展集中在现有城市中心。与此同时,波士顿奥姆斯特德的翡翠项链,已经为这个人口稠密的城市创造了一条多功能的绿道(法布斯,2004),这种积极主动的开放空间规划,在波士顿有着悠久的历史。日前,波士顿市长梅尼诺承诺,在罗斯肯尼迪绿带项目的中央干道顶层种植10万棵树,以增加城市树冠的覆盖区域。
正是在这个拥有丰富城市绿化工程历史的城市,跨学科研究项目在波士顿大都市区得以进行。城市的历史和社会经济进程形成了目前的景观格局,也便于预测未来该地区的景观变化情景。该项目团队包括波士顿市非营利性组织城市生态研究所,以及6所大学的研究人员,并由马萨诸塞州阿姆赫斯特大学的研究人员领导整个团队。该项目是由美国国家科学基金会和美国农业部林务局共同倡议并支持的城市长期研究探索区(ULTRA-EX)计划。
研究小组在利益相关者团体的帮助下,开发了一套共4个场景规划方案。以此来了解城市绿化在当地区域范围内的竞争力,以及城市的增长(包括在较大尺度的郊区化和致密化)情况。城市绿化,包括植树和社区花园,使我们能够研究地方政府给社区小规模项目的投资,对规模更大生态系统的影响。此外,我们还研究了城市人口增长、住房密度、后续土地利用、土地覆被变化和城市规模等不同变量影响下的规划方案,还探讨了城市绿化和控制增长这两股力量之间的关系。
2 目的和目标
我们的目标是,在利益相关者的参与下,研究出波士顿大都市区未来不同的发展情景,主要目的为:
(1)探索不同层次的城市绿化投资,给人和环境带来的好处,尤其对于已经城市化地区的城市绿化;
(2)量化不同程度地限制郊区化以及增加内核社区的致密化,能够给人与环境带来的不同影响;
(3)确定绿化投资或撤资、控制或不受控制建成区增长4种不同组合情况下,潜在的权衡方式、制约因素和不可预见的后果。
每个情景都需要从地区的角度来看,并着眼于在城市核心区、郊区和整个行政区的人口变化。我们的工作集中在波士顿和核心区部分,其他研究人员则研究郊区部分,重点为伊普斯维奇流域。情景分析的结果,将支持决策者和非营利组织引导公众参与,努力实现可持续发展的未来。
3 情景规划过程
我们的研究建立在现有区域规划研究的基础上:都市区规划局(MAPC)的“都市未来规划”(http://metrofuture.org)。根据MAPC对本地区的人口推算,和详细的交通分析区(TAZs)子单元,我们确定波士顿大都市区(包括波士顿市在内的101个自治区)未来的土地利用状况。两个研讨会期间,共有来自18个组织的45位利益相关方代表一起参加了情景方案的制定。2011年春季的第一次研讨会,研究团队提出了一系列由利益相关方针对未来发展方向提出并修改的初步情景方案。依据这些情景方案,研究小组为波士顿市和更广泛的大都市区,制定了未来人口增长研究的开发工具和预测草案。2012年春季的第二次研讨会,学术研究人员、非营利性组织成员以及城市和国家的决策者聚集在一起,预测草案和分析进行论证研究。研究小组对这些分析进行了修改,并继续对更详细的区域尺度的土地利用变化进行了预测。
4 情景描述
第一个情景(当前趋势)模拟了城市无节制增长的现状,增加的城市扩张和增加的郊区与核心城市之间不平等的社会经济状况。其他3个情景(都市未来规划,绿色权益,紧凑的城市核心)模拟了3个在某种形式控制下的城市生长方式,中心城市和郊区具有不同程度的新的发展。“都市未来”情景方案是基于MAPC现有的核心城市和区域中心规划,模拟了减慢郊区化的速度,与现状发展趋势情况相比,保护更多休憩用地和农田的情况。“绿色权益”情景方案是优先发展低收入社区的绿化,减少树冠覆盖面积的不平等。城市绿化优先于城市建设,城市核心区以外的空地和农田得到优先保护。最后,“紧凑的城市核心” 情景方案是在波士顿的内城核心区,重视人口发展和经济投资而不重视城市绿化。这一战略减缓了外环郊区的发展,从而保护了关联的大片空地和农田。
5 情景开发方法
我们在“当前趋势”和“都市未来”情景规划中,采用了MAPC对现有人口的推算。“紧凑的城市内核” 情景规划中,将核心社区的增长速度提高,使得郊区的增长率大约减少为“当前趋势” 的一半。依据此数据,来预测研究区域内各个亚单位(TAZ)的土地利用变化、人口增长变化和城市树冠变化。我们用上述简单的规则,来对不同的土地利用类型分配新的发展量。
在MAPC对每个亚单位(TAZ)的人口推算基础上,我们使用的房屋需求量作为一项衡量潜在住房密度变化的指标, 预估波士顿大都市区内相关的土地利用和土地覆盖变化,这其中需要经历几个步骤:首先,确认需要分区补贴和保护开放空间的发展土地,包括,为了满足规划中住房单元的增加,而可能进行增建或重建的商业、工业和住宅用地。第二,假定波士顿大都市区规划密度的增加范围,包括从密度非常低的农村社区(每亩多个住房单位)到密度非常高的城市核心区(每亩高达200套住房)。最后,对核心社区和非核心(郊区和农村)社区每个亚单位(TAZ)的住房单位的规划,制定一系列决策规则。这些规则同时还需考虑MAPC对于绿地的发展趋势预测 (开发未受保护的森林和农业土地)和建设用地的发展趋势预测(重建现有的商业和住宅用地)。
情景规划方案使我们能够根据不同区域的人口发展规划,来研究整个地区的经济增长。因此,尽管区域人口的变化是相似的,但是郊区和核心区之间增长的分配量不同(图01)。
6 结果
研究问题之一是内核心城市,包括波士顿,是否有足够的空间,来适应与人口增长相关联的高密度土地利用规划的变化。土地利用类型的变化(图02)显示,在“当前趋势”情景规划的情况下,只有约10%的规划单位将需要接受密度增加式开发,以适应人口的适度增加;而在“紧凑的城市内核” 情景规划中,超过25%的规划单位需要增加密度。
我们也对高密度的核心地区和城市绿化之间的权衡感兴趣,尤其是树冠的形式。然而,权衡可能并不简单。人们可以想象一个高密度的城市建设项目中 ,最大限度地减少建筑占地面积而增加树木种植的情形。然而,由于情景建模的复杂性,树冠部分的研究限于波士顿市和核心城区。通过在人口变化情况下的树冠研究,可以城市密度增加对现有的树冠的负面影响。然后研究透水区和不透水区(如停车场)的植树潜力,以及沿着街道确定波士顿 “绿色”城市街区的潜力。
目前,波士顿不同邻里之间的树冠覆盖范围从10%至75%不等。研究还特别对一项议题感兴趣,即能否通过在缺乏绿地的邻里区域集中植树,来克服因不平等收入而导致的树冠覆盖差异。研究表明不同情景模式下的树冠指标不同。例如 “都市未来”情景下,需要针对密度建设区(大于每平方英里13 000人)集中植树;而“绿色权益”情景主要针对低收入社区集中植树。
初步结果表明,很难实现利益相关者的一些理想结果,如达到城市树冠覆盖的社会公平(图03-04)。例如,即使将所有潜在领域都用来增加绿地,也无法将环境较差的社区达到25%的全市平均水平。因此,可能有必要开展更加积极的绿化工作,如通过重建手段进行土地用途变更,或在实际中拆掉一些建筑。
我们还对生物多样性研究小组的相关研究成果感兴趣。在进行情景研究之前,我们对波士顿最初研究发现,即使只增加少量的绿地鸟类多样性也可以增加。研究还表明,当新增绿色空间与现有的绿地具有连续性时,这种效果将更加明显(斯特巴赫等,2013)(图05)。
这一情景分析的结果表明,应着眼于努力扩大现有绿地周围树冠覆盖率,来促进城市生物多样性。但是,我们的树冠研究表明,这种策略将进一步加剧现有的社会经济不平等,使得低收入邻里的绿地越来越少而高收入地区的绿地增加。
在规划研讨会中利益相关者反馈的4个重要领域是我们进一步研究和完善情景规划的方向。首先,因为我们最初的分析主要集中在波士顿市,利益相关者还渴望明确情景规划对整个区域的影响。小组目前正在进行区域范围内研究工作,特别是土地利用变化和水质的关系方面。其次,除了树冠覆盖率,利益相关者有兴趣学习更多的绿色基础设施技术,特别是那些与雨水管理相关的技术。第三,利益相关者希望进行更多的绿地公平性讨论,例如通过绿化工作能否改善低收入社区的工作岗位和就业情况。最后,利益相关者对于不同情景的量化影响非常感兴趣。特别是量化由城市绿化和开放空间保护所提供生态服务的经济影响被视为十分重要的工作,这可以使利益相关者和政府官员对该地区的绿地和绿化工程持续投资效果更有说服力。
7  情景规划的启示
此研究可以为从事的情景规划的景观规划师们提供一些参考。我们发现在情景规划过程中,利益相关者的参与可以让我们增加了必须的“现实检查”。利益相关者指出相关领域的利害关系,对假设提出质疑,有利于增强最终方案的现实性,使其解决波士顿地区内独特的特性和情况。我们还发现,将建议的人口变化转化为实际的土地利用和土地覆盖变化的工作比预期更具挑战性。
对于像波士顿这样已经高度发达的城市,增加密度需要对现有的社区和重建的商业或旧工业用地填充新的发展内容。我们必须在波士顿现有的城市开发密度基础上,开发属于自己的一套规则和指导方针。未来景观规划工作将受益于具有标准化填充式的开发模型,并且有利于在更大的区域内复制的情景规划。与利益相关方合作,共同确定切合实际的填充密度和适当的土地用途改变方式的过程,是整个规划的重要组成部分。总之,情景规划对于景观规划师来说非常有用,可以帮助他们为社区创造更可持续的未来,增加城市绿色空间,同时容纳日益增长的城市人口的需要。
致谢:
本文从先前发表的中期情况报告(2012年6月)获得了主要的资料来源,并与2013年4月12-13日在马萨诸塞州阿默斯特的2013法布斯景观和绿道规划会议:可持续发展之路的论文集中第一次发表。感谢城市生态研究所的维多利亚沃尔夫、波士顿市以及情景研讨会参与者们对这个项目鼎力支持。我们还要感谢情景研究小组的其他成员,包括艾力克·斯塔罗斯、科林·波尔斯基、凯特·图克、苏珊娜·乐曼和 凯瑟琳·福。本项目的资金来自美国国家科学基金会BCS-0948984和U.S.D.A.马萨诸塞州农业试验站,项目编号MAS009584。
The Boston Metropolitan Area Urban Long-term Ecological Research Area (BMA-ULTRA-EX) Project is an interdisciplinary project that is studying the effects of socio-economic and bio-physical drivers on urban ecosystems.  The Boston region is experiencing low-density urban sprawl (suburbanization) on the rural-urban fringes of the metropolitan area that is creating environmental impacts to natural resources.  At the same time, central cities such as Boston are seeing disinvestment in some low-income neighborhoods causing property abandonment, along with limited infill development (densification) near the commercial core and transit hubs. 
These competing socio-economic forces of suburbanization, densification, and disinvestment have environmental implications for urban ecosystems, including urban forest canopy, water quantity and quality, and biodiversity. Landscape planning initiatives to address these issues will require a pro-active approach to concentrating development on currently built lands and in the suburban fringe to protect forests, farms and other natural resources, while greening and enhancing ecosystem services in the current high-density urban core.
It is within this landscape planning setting that the research team used a stakeholder- driven process to develop a set of four planning scenarios to explore the future of the region. This paper will describe the planning process with stakeholders to develop these plans, along with the preliminary analyses.  It will conclude with insights for other landscape planners engaged in scenario planning.
1 Background
Scenario planning is a unique tool that allows planners to visualize alternative futures in order to deal with temporal change and multiple spatial scales (Myers and Kitsuse, 2000). Scenarios are flexible and adaptable to potential future conditions; providing a strategy for responding to the uncertainty inherent in land use planning (Peterson et al., 2003; Klosterman; 2007; Steinitz et al., 2003).  They allow planners to develop benchmarks that illustrate the implications of different futures for a range of systems, including economic, ecological, and social.  They are also very useful tools for engaging stakeholders and the public in landscape planning by showing them the ramifications of different decisions, making the planning process more visible and transparent (Gunder, 2008).
The Boston Metropolitan Region with a population of 4.48 million is the 10th most populous in the U.S., yet is expected to only experience moderate population growth in the coming decades.  However, new development, primarily at the urban fringe, is expected to consume 152,000 acres of open space, including 58,000 acres of rare and endangered species habitat (Metro Future, 2009).  This urban sprawl has precipitated planning efforts to try to concentrate new development within existing urban centers.  At the same time, Boston has a long history of proactive open space planning beginning with Olmsted's Emerald Necklace to create a multifunctional greenway in this densely populated city (Fábos, 2004).  Currently, Boston's Mayor Menino has pledged to plant 100,000 trees to increase the urban tree canopy, as well as completed the Rose Kennedy Greenway on top of the Central Artery Project.
It is under this rich history of urban greening projects that an interdisciplinary research program was developed for the Boston Metropolitan Area to understand the historical and socio-economic processes that led to the current landscape pattern and to project future landscape change scenarios for the region.  This project team involves the City of Boston, non-profit Urban Ecology Institute, and researchers from six universities, led by the University of Massachusetts Amherst. The project was funded by a new joint initiative of the National Science Foundation and USDA Forest Service known as the ULTRA-Ex (Urban Long-term Research Areas Exploratory) program. 
The research team developed a set of four scenarios in conjunction with stakeholder groups to understand the competing forces of urban greening at the local scale, and urban growth, including suburbanization and densification at the larger scales.  Urban greening, including tree planting and community gardens, allowed us to study the impacts of municipal investment in community-focused small-scale projects on the larger ecosystem-scale.  In addition, we studied the impact of different controlled growth efforts on population, housing density and subsequent land-use and land-cover changes at the city and metropolitan scales.  We also explored the relationship between these two forces of urban greening and controlling growth.
2 Goals and Objectives
Our goal was to develop alternative future growth scenarios in the Boston Metropolitan Region with stakeholder input that aim to:
(1)Explore outcomes for people and the environment of different levels of investment in urban greening, particularly tree canopy cover in already urbanized areas;
(2)Quantify impacts on both people and the environment of varying levels of restrictions on suburbanization versus the impacts of increased densification in inner core communities;
(3)Identify potential tradeoffs, constraints and unforeseen consequences of four different combinations of greening investment (or disinvestment) and controlled or uncontrolled growth.
Each scenario takes a regional perspective and looks at population changes in urban inner core, suburbs, and region. Our workshops focused on the Boston and inner core portion, and other studies are looking at impacts on the suburbanizing portion of the region, focusing on the Ipswich watershed. The combined results of the scenario analysis will support policy makers and nonprofits in their ongoing efforts to engage the public in achieving a sustainable future.
3 Scenario Planning Process
Our study builds on the existing planning studies for the region: the Metropolitan Area Planning Council's (MAPC) MetroFuture plan (http://metrofuture.org).  We used the MAPC's population projections for the region, and detailed sub-units, called Transportation Analysis Zones (TAZs) in order to determine future land use for the 101 municipalities in the Boston Metropolitan Area, including the City of Boston.  The scenarios were developed in conjunction with 45 stakeholders from 18 organizations during two workshops. At the first workshop in spring 2011, the research team presented a range of preliminary scenarios that stakeholders selected and modified for future development.  The research team then developed tools and projected draft maps of future population growth in Boston and in the broader metropolitan area under each scenario.  At the second workshop in spring 2012, academic researchers, non-profit members, and municipal and state decision makers gathered to provide feedback on these draft scenario maps and analyses.  The research team made modifications to the analysis and continues to work on more detailed regional-scale land-use change projections.
4 Scenario Descriptions
The first scenario (Current Trends) follows the status-quo of uncontrolled growth with increased urban sprawl and increasing socio-economic inequities between suburbs and the central core cities.  The other three scenarios (MetroFuture, Green Equity, and Compact Core) have some form of controlled growth, but differ in the ratio of new development allocated to the central cities and suburbs.   The MetroFuture scenario is based on MAPC's existing plan that includes densification of the inner core cities and regional centers, which slows the rate of suburbanization and protects more open space and farmland than the Current Trend scenario.  The Green Equity scenario prioritizes greening lower-income communities over urban density, while reducing inequalities in tree canopy cover.  Urban greening is prioritized over urban density or protection of open space and farmland outside the urban core.  Finally, the Compact Core scenario concentrates population and economic investment infill in inner cities such as Boston but downplays urban greening efforts.  This strategy slows development in the outer-ring suburbs, which protects large tracts of connected open space and farmland. 
5 Scenario Development Methodology
We used the MAPC's existing population projections for the MetroFuture and Current Trends plans.  For the Compact Core, the growth rate for the inner core communities was increased, which resulted in a suburban growth rate of approximately half the Current Trends scenario.  The population growth was then used to project changes in land use and urban tree canopy for the planning sub-units (TAZ's) within the study area.  We used simple rules described above to allocate the amount of new development to different land use categories. 
Based on MAPC's population projection in each TAZ, we used the demand of housing units as an indicator in gauging the potential housing density change for estimating associated land use and land cover change in the Boston Metropolitan Area.  Several steps have been involved in transforming MAPC's population projection into land use and land cover change.  First, developable lands based on zoning allowance and protected open space were identified, including current commercial, industrial, and residential land uses that could be infilled and redeveloped to accommodate projected housing units increase. Second, assumptions for a range of projected density increase in the Boston Metropolitan Area were made from very low density (more than one housing unit per acre) in rural communities to very high density (up to 200 housing units per acre) in the urban core areas.  Finally, a set of decision rules were made to allocate projected housing units in each TAZ between inner core and non-core (suburban and rural) communities based on MAPC's projected development trends in greenfill (development on unprotected forest and agriculture lands) and infill (redevelopment in existing commercial and residential lands) in the region.  
The scenarios allowed us to study varying distributions of growth across the region, which were based upon allocating the projected regional population to different areas.  Thus, while the regional population changes were similar, the allocation of growth between suburbs and the inner core differed (Fig.01).
6 Results
One of the research questions was whether the inner-core cities including Boston would have enough room to fit the high density projected land use change associated with this population growth.  The changes in land use type (Fig.02) show that under the Current Trends scenario, only about 10% of the planning units would need to accept infill development to accommodate the modest increase in population, while over 25% of planning units in the Compact Core scenario would have increased density.
We were also interested in whether there would be trade-offs between densification of the inner core areas and urban greening, especially in the form of tree canopy.  However, the trade-offs may not be straightforward.  One could imagine a high-density infill project that minimizes the building footprint and increases tree plantings.  However, due to the complexity of the scenario modeling, the tree canopy part of the study was limited to the City of Boston and inner core cities. The tree canopy study (described in detail in Danford et al., in review) used population change to determine the negative impacts of increased density on existing tree canopy.  The study then looked at tree planting potential in pervious areas, impervious areas (i.e., parking lots); and along streets to determine the ability to "green" urban neighborhoods in Boston. 
Currently, tree canopies range from under 10% to over 75% canopy cover between Boston neighborhoods.  In particular, this study was interested in understanding if focusing tree planting in under-served neighborhoods could overcome the inequities in tree canopy based upon income.  The study allocated the tree canopy differently for each scenario. For example, the MetroFuture plan focused tree planting in the new higher density infill areas (greater than 13,000 people per sq. mi.), while the Green Equity scenario focused tree plantings in low-income neighborhoods.
The preliminary results indicate that it is difficult to achieve some of the desired outcomes identified by stakeholders, such as social equity with respect to urban tree canopy (Fig.03 & 04). For example, even increasing tree canopy in all potential areas, did not significantly bring many environmental justice neighborhoods up to the city-wide average in tree canopy of 25% (Danford et al. under review). Thus, there may be a need for more aggressive greening efforts that occur as part of redevelopment as land uses change or buildings are actually removed.
We were also interested in applying some of the research team's studies of biodiversity to the scenario efforts.  Our initial studies in Boston, previous to conducting the scenarios, found that bird diversity increases even with small amounts of additional green space, but suggests that this effect is more pronounced when the new green space is contiguous with existing green spaces (Strohbach et al, 2013) (Fig.05). 
Applying this to the scenario results to date suggests that efforts to promote urban biodiversity should focus on expanding tree canopy around existing green spaces.  However, our tree canopy research suggests that this strategy would further exacerbate the existing socio-economic inequities between lower-income neighborhood with fewer trees and high-income areas that are already very green.
Stakeholder feedback during the planning workshops highlighted four important areas for further study and refinement of our scenarios. First, since our initial analysis focused primarily on the City of Boston, stakeholders were interested in knowing the regional implications of the scenarios.  The team is currently working at the regional scale, particularly with regards to the relationship between land use change and water quality.  Second, stakeholders were interested in learning more about the implications of other green infrastructure techniques besides tree canopy, especially those related to stormwater management. Third, stakeholders wanted to the discussion of equity to include more than lack of green space. According to them, jobs and employment are a major issue for improving lower-income neighborhoods that needs to accompany greening efforts.  Finally, stakeholders were very interested in quantifying the impacts of the different scenarios.  In particular, quantifying the economic impacts of the ecosystem services provided by urban greening and/or open space protection was seen as vital to convince stakeholders and government officials in the region about the efficacy of continued government investment in green space and greening projects.
7 Implications for Scenario Planning
This research study can offer several insights for landscape planners who are engaged in scenario planning.  We found that engaging stakeholders in the scenario planning process allowed us to add a much needed "reality check."  The stakeholders pointed out relevant areas of interest, questioned assumptions that were being made, and were keenly interested that the final scenarios were realistic and addressed the unique characteristics and settings found within the Boston region.  We also found that converting proposed population changes to actual land-use and land cover change to be more challenging than expected.
In an existing highly developed city such as Boston, increasing density requires infill of new development within either existing neighborhoods or redevelopment of commercial and old industrial land.  We had to develop our own set of rules and guidelines for infill based on densities that already occur within Boston.  Future landscape planning efforts could benefit from having standardized infill development models to help replicate scenarios across a larger region.  Working with stakeholders to determine realistic infill densities and appropriate land-uses to change is an important part of the process.  In summary, scenarios are very useful for landscape planners to help their communities articulate a vision for a more sustainable future that increases urban green space while accommodating the need of growing urban populations.
Acknowledgements:
This paper draws heavily from a previously published interim scenario report (June 2012) and first appeared in the Proceedings of Fábos Conference on Landscape and Greenway Planning 2013: Pathways to Sustainability. Amherst, Massachusetts, April 12-13, 2013. Thanks to the Urban Ecology Institute, Victoria Wolff, and City of Boston for their support with this project, as well as the scenario workshop participants.  We would also like to thank the other members of the research team who worked on the scenarios, including Eric Strauss, Colin Polsky, Kate Tooke, Susannah Lerman, and Katherine Foo.  Funding for this project came from the NSF BCS-0948984 and U.S.D.A. through the Massachusetts Agricultural Experiment Station Project No. MAS009584.
References:
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[4]Klosterman R. E. Deliberating about the Future[M]. Hopkins L. D., M. A. Zapata. In Engaging the Future: Forecasts, Scenarios, Plans, and Projects. Cambridge, Mass.: Lincoln Institute of Land Policy, 2007:199-219.
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作者简介:
劳勃·L.·莱恩/博士/ASLA成员/马萨诸塞大学阿默斯特分校(美国)风景园林和区域规划学院教授/研究方向:绿道和绿色基础设施规划、研究方法、环境与行为。
佩格·S.·瓦伦/博士/马萨诸塞大学阿默斯特分校(美国)环境保护学院副教授/波士顿ULTRA-EX项目主要研究者。
克雷格·妮可森/博士/马萨诸塞大学阿默斯特分校(美国)环境保护学院可持续发展计划负责人/波士顿ULTRA-EX项目联合首席研究员。
郑景雯/博士生/马萨诸塞大学阿默斯特分校(美国)风景园林和区域规划学院。
瑞秋·丹福德/博士生/马萨诸塞大学阿默斯特分校(美国)环境保护学院。
迈克尔·斯特巴赫/博士/德国不伦瑞克生物多样性研究所博士后研究员。
Biography:
Robert L. RYAN, PhD, ASLA, is a Professor at the Department of Landscape Architecture and Regional Planning, University of Massachusetts, Amherst (USA) where he teaches courses on greenways and green infrastructure planning, research methods, and environment and behavior.
Paige S. WARREN, PhD, is an Associate Professor in the Department of Environmental Conservation, University of Massachusetts, Amherst, and is principal investigator for the Boston ULTRA-Ex project.
Craig NICOLSON, PhD, is Director of Academic Sustainability Programs in the Department of Environmental Conservation, University of Massachusetts, Amherst and co-principal investigator for the Boston ULTRA-Ex project.
Chingwen CHENG is completing her PhD in Regional Planning in the Department of Landscape Architecture and Regional Planning, University of Massachusetts, Amherst.
Rachel DANFORD is a PhD student in the Department of Environmental Conservation, University of Massachusetts, Amherst.
Michael STROHBACH, PhD is a post-doctoral research scholar at the Thünen Institute of Biodiversity, Braunschweig, Germany
译者简介:
孙帅/1986年生/男/山西人/博士/北方工业大学建筑工程学院讲师/研究方向:绿道规划设计研究(北京 100144)
About the Translator:
SUN Shuai, PhD, was born in Shangxi Province, 1986. He is a lecturer in College of Architecture and Civil Engineering, North China University of Technology. His research interest lie in Greenway planning and design.(Beijing 100144)
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