A framework for street tree planning in urban areas in Israel

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<ul><li><p>Landscape and Urban Planning, 19 ( 1990) 203-2 12 Elsevier Science Publishers B.V.. Amsterdam - Printed in The Netherlands </p><p>203 </p><p>A Framework for Street Tree Planning in Urban Areas in Israel </p><p>S. AMIR and A. MISGAV </p><p>Technion-Israel Institute of Technology, Faculty ofArchitecture and Town Planning, Haifa 32000 (Israel) </p><p>(Accepted for publication 18 January 1990) </p><p>ABSTRACT </p><p>Amir, S. and Misgav, A., 1990. A frameworkfor street tree planning in urban areas in Israel. Landscape Urban Plann., 19: 203-212. </p><p>This article presents the methodological as- pects of a proposed planning process for an ur- ban street tree system. The process specifies goals and objectives for street tree planning, cri- teria for evaluation of process output, develop ment stages in the preparation of conceptual and detail planting plans and a case study for dem- onstrating the use of an analysis method to de- </p><p>termine the suitability of site/tree projile of a given street. </p><p>Based on the use of subjective and objective data sources, the process could be adapted for use in the planning of other urban vegetation areas. The contribution of such a process to de- cision making depends on availability of data on site conditions and on species selection choices that are provided by the list being used. </p><p>INTRODUCTION </p><p>The increased intensity in development of urban areas often creates environmental con- ditions which will not support the continuous existence of street trees (Hubbes, 1975 ) . Past studies often show that there is a need for a conscious planning policy and management of street trees to prevent the persistent and ongo- ing destruction of this resource. </p><p>Clark ( 1978) indicates that trees generally have a low priority among decision makers. Public authorities often view tree planting </p><p>largely as a visual enhancement effort. They often do not take into consideration the broader environmental and functional roles that such trees possess (Rousakis, 1978). </p><p>Several studies have examined the functions of urban trees (Brown, 1983; Yahav, 1986) and Robinette ( 1972) classified the functions of trees as architectural, functional, engineering, climatic and aesthetic. Economic values were studied by Payne ( 1978) and Johnson et al. ( 1982) analysed their social and psychological functions. Pitt et al. ( 1979) dealt with climatic and engineering functions, while Appleyard </p><p>0169-2046/90/$03.50 0 1990 Elsevier Science Publishers B.V. </p></li><li><p>204 S. AMIR AND A. MISGAV </p><p>AND OBJECTIVES </p><p>EVELOPHENT kF ti ONCEPNAL *n?!=r Tll!TF </p><p>\i EVRL~PHENT F ETAILED PLAN </p><p>J PHySICAL/ VISUAL CHARACTER OF ME STRREET </p><p>CLIMATE CONTROL NOISE ABATEMENT AIR POLLUTION </p><p>E </p><p>lwxhr.AIN F TReET \I REES r, DETEF.~~INEc I </p><p>I </p><p>ELECTION F REE SPECIES </p><p>EFINE PREPERRED LIMATE. NOISE, ISUAL CONTROL </p><p>SPECIES VARIETY SPECIES IN ONE </p><p>Fig. 1. Street tree planning process. </p></li><li><p>URBAN STREET TREE PLANNING IN ISRAEL 205 </p><p>( 1978) investigated trees as an aesthetic as- pect of the urban environment. Environmen- tal functions of trees were studied by Rich ( 1970) for air pollution and amelioration, and by Schiller ( 1984) for noise control. </p><p>Street tree resource management has lacked a long-range and coordinated approach that would ensure the biological needs of trees. Un- like most of the urban infrastructure, trees are living units and are the concern of many professionals. Andresen ( 1975 ) indicated that in many cities management tools that go be- yond the day-to-day problem-solving type are lacking. Growth and the enduring viability of trees require a management system that can assess the impact of daily actions on the con- tinuous existence of a tree population. What is often lacking is a clear and predetermined pol- icy that identifies urban trees as a living re- source and one that fulfils multiple functions. Such a policy necessitates an ongoing planning and management system whose goal is to en- sure the existence of trees and their develop- ment over time. </p><p>This article presents the content and stages of a proposed planning process for an urban street tree system in Israel. </p><p>Past studies have suggested various contents and structures for street tree management sys- tems and the means for their implementation. Grey and Deneke ( 1986), International City Management Association ( 1982)) Howard and Hudson ( 1984), Tate ( 1984), Johnson et al. ( 1982 ) all identified the importance of includ- ing the following three elements as a part of any management system: inventory of the re- source, plan for new planting and a strategy for resource maintenance. In addition to such professional elements, several administrative aspects have been suggested for inclusion such as long-range planning for manpower, and budget, as management tools which indirectly impact the well-being of the resource. </p><p>The process described below is one of three issues that emerged in the original study, (see Fig. 1): ( 1) development of methods for in- </p><p>ventory of the street tree population; (2) de- sign of a planning process and of its update for planting street trees; (3) development of a maintenance program for urban trees. Details of the descriptive model and proposed main- tenance program are not included here, but are described in Amir and Misgav ( 1988 ). </p><p>In preparing the plan, we followed a four- stage process: ( 1) specification of the problem through the identification of goals and objec- tives; (2) development of evaluation criteria needed to assess the quality of the results; (3) generation of development and detailed street tree plans; (4) demonstration of the use of the process in a case study. </p><p>GOALS AND OBJECTIVES FOR URBAN STREET TREE PLAN </p><p>This stage provided the conceptual basis of the plan that is based on preference by deci- sion makers, on past studies and on research generated from case studies. This stage was di- vided into four elements: goals, objectives, means and criteria. The subjects divided into three groups (spatial-visual, function and bi- ological-physiological aspects) and are pre- sented in Fig. 2 in an hierarchical order, from the general to the specific. </p><p>Goals and objectives are concerned with two uses: ( 1) as a broad and general system which is relevant to any city-scale street tree planting plan; (2 ) as a framework that defines the con- tent of a specific plan prepared for smaller areas such as a neighbourhood or the individual street. The goals-objectives framework relates to specific characteristics of a site and its conditions. </p><p>The proposed street tree plan has four major goals. The most important goal is the selection of tree species with the greatest suitability for a given location. The second goal deals with the achievement of a major function of trees in cit- ies as providers of a green living environment. Trees give special landscape character to a place. 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G</p><p>oals,</p><p> obj</p><p>ectiv</p><p>es, </p><p>mea</p><p>ns a</p><p>nd c</p><p>riter</p><p>ia fo</p><p>r th</p><p>e pla</p><p>nning</p><p> st</p><p>reet</p><p> tre</p><p>e sy</p><p>stem</p></li><li><p>TABL</p><p>E 1 </p><p>Crite</p><p>ria </p><p>and </p><p>mea</p><p>sure</p><p>s fo</p><p>r sit</p><p>e ev</p><p>aluat</p><p>ion </p><p>and </p><p>tree </p><p>spec</p><p>ies </p><p>sele</p><p>ctio</p><p>n </p><p>Crite</p><p>ria </p><p>Type</p><p> Cr</p><p>iteria</p><p> M</p><p>easu</p><p>res </p><p>Leve</p><p>l 1 </p><p>Leve</p><p>l 2 </p><p>Leve</p><p>l 3 </p><p>Visu</p><p>al an</p><p>d sp</p><p>atia</p><p>l </p><p>Tree</p><p>Tree</p><p> Tr</p><p>ee </p><p>Tree</p><p>Tree</p><p> Bo</p><p>th </p><p>Both</p><p> Si</p><p>te </p><p>Site</p><p> Si</p><p>te </p><p>Site</p><p>Phys</p><p>ical </p><p>and </p><p>biolog</p><p>ical </p><p>Both</p><p>Tree</p><p> Tr</p><p>ee </p><p>Tree</p><p> Tr</p><p>ee </p><p>Tree</p><p>Func</p><p>tiona</p><p>l Bo</p><p>th </p><p>Both</p><p> Bo</p><p>th </p><p>Site</p><p> Si</p><p>te </p><p>Tree</p><p> size</p><p>: Cro</p><p>wn </p><p>Heig</p><p>ht </p><p>Tree</p><p> for</p><p>m </p><p>Tree</p><p> tex</p><p>ture</p><p> Tr</p><p>ee c</p><p>olou</p><p>r: Le</p><p>aves</p><p> Bl</p><p>osso</p><p>m </p><p>Crow</p><p>n de</p><p>nsity</p><p> Pl</p><p>antin</p><p>g de</p><p>nsity</p><p> Pl</p><p>antin</p><p>g ar</p><p>rang</p><p>emen</p><p>t Co</p><p>nstru</p><p>ctio</p><p>n de</p><p>tails</p><p> St</p><p>reet</p><p> fur</p><p>nitur</p><p>e Fo</p><p>regr</p><p>ound</p><p> vie</p><p>ws </p><p>Plan</p><p>t va</p><p>riety</p><p>Clim</p><p>atic </p><p>regio</p><p>n </p><p>Grow</p><p>th </p><p>rate</p><p> to: </p><p>Life </p><p>expe</p><p>ctan</p><p>cy </p><p>Decid</p><p>uous</p><p>/eve</p><p>rgre</p><p>en </p><p>Form</p><p> of g</p><p>rowt</p><p>h Nu</p><p>isanc</p><p>es </p><p>Envir</p><p>onm</p><p>enta</p><p>l se</p><p>nsiti</p><p>vity </p><p>Regu</p><p>lation</p><p> of</p><p> m</p><p>icroc</p><p>limat</p><p>e Sc</p><p>reen</p><p>ing a</p><p>bility</p><p> No</p><p>ise a</p><p>bsor</p><p>ption</p><p> Tr</p><p>affic</p><p> co</p><p>ntro</p><p>l Do</p><p>min</p><p>ant </p><p>land </p><p>use </p><p>Narro</p><p>w: </p><p>&lt; 5 </p><p>M </p><p>Low:</p></li><li><p>208 S. AMIR AND A. MISGAV </p><p>the aesthetic, climatic, environmental, traffic and safety qualities of the city. The fourth goal concerns the contribution of trees to the reduc- tion of conflict between conditions needed for their long-range survival and human activities in their immediate environment (Fig. 2). </p><p>Six objectives were identified that provide a basis for management (Fig. 2 ) . They are in- tended to achieve maximum suitability be- tween trees and their site environment in three areas: the spatial-visual, biological-physical and the functional. The objective of the pro- cess is to arrive at an optimum among these areas. To make the framework operational, a set of criteria and means was developed. Cri- teria were used to evaluate the degree to which a given street tree design achieved the stated objectives. </p><p>Three sets of criteria were developed to re- late to two types of tree planning tasks. The first is concerned with tree selection, the second with site suitability, the third with both tasks. Visual-spatial criteria are intended for use in the evaluation of the degree to which a tree is suitable for a site with a given visual quality. The second group is concerned with evalua- tion of tree suitability for a site with a given growth and physical constraint. The third type evaluates the degree to which a tree is likely to fulfil a function that would ameliorate the cli- matic or other environmental conditions. Cri- teria and measures for the evaluation of trees and sites, or both, are identified by subject and type of task in Table 1. </p><p>PROCESS FOR GENERATING A CONCEPTUAL STREET TREE PLAN </p><p>The plan-making process is based on the content developed in the goals-objective stage. This includes the preparation of two plans: one for general guidelines and another for detailed street planting. </p><p>The conceptual stage includes design guide- lines and the preparation of a city-wide plan. An important function of the latter is to pro- </p><p>vide a comprehensive decision-making frame- work. It makes the implementation of design guidelines in local plans feasible. One of the plans objectives is to develop agreeable visual and landscape identities for various parts of the city. It is intended to secure a given visual and spatial form in the organization of new planting. </p><p>In the preparation of the conceptual plan, decisions were based on three design elements: spatial arrangements of trees, their size and form. Three types of spatial arrangement were identified for use: the formal arrangement, non-formal and a combination of the two (see Table 1). Tree size is concerned with the di- mension of the diameter of the crown and the height of the tree. For planning objectives, trees were divided into three groups: small, medium and large. The third design element is tree form which defines the space of streets, the type of care that is needed by the tree and the func- tions that a tree could fulfil. </p><p>As shown in Fig. 1, the first stage in plan preparation is specification of measures, as de- fined in Table 1. The three elements are used in the following sequence: arrangement, size and form. To develop a tree profile, the ele- ments are combined through two matrices, ar- rangement/size, with the resulting combina- tions brought together with form. This results in the specification of a wide range of tree pro- files. Each profile with its characteristics con- stitutes the basis for evaluation of the suitabil- ity of trees for various site conditions. </p><p>The profile data are used with a set of pre- determined design principles to develop a gen- eral planting plan, as is demonstrated for the case study below. The final product, at this stage, does not name tree species, but specifies design principles and tree profiles to be ap plied in each street. It is intended that the con- ceptual stage will provide sufficient flexibility to enable the completion of detailed design for various sites. Such design could take into con- sideration additional tree-specific and site-re- lated aesthetic and functional factors. </p></li><li><p>URBAN STREET TREE PLANNING IN ISRAEL 209 </p><p>DETAILED STREET PLANTING PLAN </p><p>Once tree arrangement, size and form for a given street type are specified, it is possible to complete the preparation of a detailed street planting plan. This stage includes detailed studies of site characteristics and the selection of tree species. Site evaluation is made on the basis of three groups of criteria: spatial-visual, biological and functional (Table 1). Site suit- abilities and limitations on tree growth and function were identified. This information was then used as a basis for the selection of species suitable for a site. The tree species selection process includes three stages: ( 1) develop- ment of a street tree list; (2) selection criteria ordering; (3) selection of species. </p><p>A general tree list was based on existing lists and on other written sources that helped verify the suitability of species as street trees. Data describing the trees in the list were classified according to size and to four groups of site characteristics: physical, tree growth condi- tions, site maintenance factors and site aes- thetic qualities. Table 2 presents a sample tree profile. </p><p>Criteria classification provided a basis for the description of trees in the general list (Ta- ble 1). The use of the list for the selection of the most suitable tree for a site required the or- dering of criteria according to importance. </p><p>Criteria were classified into those of pri- mary and secondary importance (Table 2). The first included all those that are mandatory for the continuous existence of a street tree. The second group were considered not mandatory. Ten types of criteria were used in the case study. The primary upper, the more important group, are concerned with visual, bio-physical, and maintenance subject, and the secondary with visual and functional criteria. Criteria were also ordered within the group as indicated by the numbers l-3 (Table 2 ) . </p><p>Street trees were selected from a general list through a two-stage elimination process. In the first stage, a list of potential tree selections for </p><p>a street is evaluated according to the primary criteria. Only those trees that satisfied all the primary criteria were retained on the list. The new list is then evaluated using the secondary criteria. In this stage, the less suitable trees are not dropped from the list, but are placed in a less preferable position. This o...</p></li></ul>


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