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Case studyUtrecht

GREEN STRUCTURE AND URBAN ECOLOGY OF UTRECHT

Sybrand Tjallingii - Faculty of Architecture, Delft University of Technology

February 2003

1. Introduction

Urban green structure is a new concept that points at the way urban green areas connect to each other and to the urban structure as a whole. In the 1980s, practitioners and researchers introduced the green structure concept to discuss their analysis of green network relations and to improve planning conditions for the role of green areas in urban environments. In 2000, the European Commission's initiative to stimulate CO-operation in Science and Technology (the COST action programme) provided an opportunity to start a COST action devoted to the issues of green structure and urban planning (www.map21ltd.com/COSTC11). The participants in the COST action decided to have working groups for different aspects: planning issues, human values and use and ecology. Acknowledging the impossibility to strictly separate these aspects in urban practice, we expect to throw more light on the role of urban green structure if we look at it from different points of view. The ecological viewpoint is the basis of this case study on Utrecht.

The meaning of ecology is not self-evident. In municipal practice urban ecology often refers to the study of wildlife in urban environments. Yet, plants and animals are highly dependent on human values and their protection or control requires planning. The Ecology working group therefore decided to focus on ecological processes: the physical processes that create conditions for both urban residents and wildlife. Thus, the ecological viewpoint is rather process-oriented than object-oriented (Tjallingii, 2000). This leads to the following questions that will structure the case study report.

 

1. What are the elements of the local green structure and how did natural and cultural factors contribute to its present pattern?

2. How is the urban green structure related to local biodiversity? How green structure may create conditions for enrichment?

3. How does the local green structure relate to human health? What is the role of pests?

4. How is urban green structure related to local climate and hydrology? How may green structure create conditions for enhancement?

5. How are green resources used and managed? What is the role of forestry and farming? How does the local green structure relate to the flow of organic matter?

6. What is currently recorded about green structure? And how are monitoring results used in evaluation studies?

7. What are the objectives of green structure planning? How are these objectives related to policy instruments?

 

The second section of this paper discusses the origin of the local green structure; section 3 deals with the questions 2-6 and the last question is the focus of section three.

The case study is based on the actor's active participation in several municipal projects concerning water and green planning and the management of public open space. For this report the information was completed by an analysis of documents and some interviews with key persons.

 

2. Origin and nature of the Utrecht green structure

 

This section analyses the natural and cultural history of the network of green areas that has been named the Utrecht green structure. After an introduction to the landscapes of the Utrecht region, the history of the city's green structure will be related to a number of driving forces and transformation processes in urban development.

 

2.1 Urban development and landscapes

 

Presently, the city of Utrecht has approximately 250,000 inhabitants who live on a surface of 91 km2. The Utrecht urban region has more than half a million inhabitants and is a part of the Randstad Holland metropolitan area. On the western edge of this urban region is the so-called Green Heart, an open meadow-landscape of approximately 50 km wide that is the central part of the horseshoe of Randstad cities. To the east, Utrecht borders on a wooded hill ridge pushed up by glaciers in the ice age. South of the city, the big rivers belonging to the Rhine delta dominate the open meadow landscape. West and north of Utrecht the rivers used to meet the sea and the resulting stagnant waters created big swamps where thick layers of peat could develop. From the Middle Ages till the nineteenth century, peat provided fuel for the early industrial development in the cities. In the beginning, the land was still dry and peat could be cut from the surface. Later the pits filled with water and dredging was the only way of peat mining. The result is a landscape of lakes north of Utrecht. To the west the rivers deposited clay on the peat layers. The basis of these different landscapes is in their geology and soils: glacial sands to the east, peat in the northern and western polders and river clay to the south. A long cultural history has transformed this rough basis into a rich variety of green areas. Apart from the northern lakes, where recreation is the leading activity, most of the green land is still in agricultural use. But urban land-use is rapidly taking over.

 

Figure 1. Landscapes of the Utrecht region.

The map shows the rivers, running from east to west. The brown coloured areas to the east are woodlands. To the north, a landscape of lakes is visible. All the white areas around the city are meadows. The traffic network is in black and the water network in blue. The map further shows the red 3-kilometre distance line and the circle, which indicates the 10-kilometre distance from the built-up area. (source: Gemeente utrecht, 2000).

 

 

2.2 The green structure of streams

 

The first and most basic process that structures green areas in the city is the meandering of rivers. De Bruin, van Dam and Wassink (1988) edited a rich description of this history. The origin of Utrecht's spatial structure goes back to the Romans who founded the city two thousand years ago at a point where they could cross the river Rhine. The name Utrecht is derived from Ultrajectum, the last bridge. In those days it was a real effort to cross the river that was the northern boundary of the Roman Empire. In the centuries that followed, the river Rhine transferred the bulk of its flow to more southerly channels. In the middle ages the Utrecht branch of the Rhine was cut off from the main stream. The tamed river became a more convenient waterway and the high banks that used to protect the city from the floods lost their function. Merchants used the high banks to build their warehouses and workshops. Today, there is only a small stream called Kromme Rijn, that meanders through the city where it splits up in two: the river Vecht goes north towards the old Zuiderzee, the sea near Amsterdam and the Leidsche Rijn flows to the west to reach the North Sea near Leiden. These three, together with some smaller parallel branches are the network of streams that shapes the urban street pattern. The rivers in the inner city, the Oude Gracht and Nieuwe Gracht, have a high road and a low road with trees. Pedestrians can walk down the stairs and sit in the outdoor cafés and restaurants that now have taken over the occupation of the old high bank warehouses. Richness in the details of nature and culture, like wall vegetation and sculptured lantern consoles, contribute to the typical Utrecht river profile that is not found in any other Dutch city (figure 2).

 

Figure 2. River branches have shaped the old city.

The maps show the old meanders of the river and the present street pattern. The cross section shows the typical profile with the two levels.

 

In the surrounding countryside towpaths accompany the Kromme Rijn, Leidsche Rijn and Vecht rivers. Once used to pull vessels, they now are footpaths that offer nice walks with beautiful views on the water and on the estate parks that were planted along the river by well to do citizens in former centuries. Parks accompany the rivers in the outer parts of the city and in the inner city trees line up along the waterways and turn them into greenways (figure 3).

 

Figure 3. The green structure of streams.

River branches shape the urban green structure and link the inner city green areas to the surrounding countryside.

 

 

2.3 The green structure of defence works

 

the walks of Jan David Zocher

The second process that has structured green areas in Utrecht is the history of defence works that have been transformed into parks. In the seventeenth century, the medieval brick walls were reinforced with earthen walls but, soon, also these renewed defence works could no longer resist the enemy's cannonballs. At the beginning of the nineteenth century, new fortresses built outside the city made the old city walls redundant as defence works. Moreover, the old walls were felt as a brick corset (Zijlstra, 1988: 32) for the growing population of city. The city needed new space for further growth. What was left of the ramparts and towers had turned into a messy edge area and the city council felt it was necessary to improve the image of the city in order to attract wealthy merchants and give a new incentive to economic development. The large number of unemployed and poor citizens would also benefit from this development. In 1827 the council decided to demolish the old walls and replace them by a park. The task to design the new walks was given to the famous landscape architect Jan David Zocher, who had performed a similar task in Haarlem and who, later, would become the designer of the Amsterdam Vondelpark. The brick walls were demolished and the earthen walls were turned into little hills. Thus, Zocher created an excellent starting point for a beautiful English Landscape style design that was realised in the years between 1830 and 1860 (Becker-Jordens & de Vries, 1973). Today, the Utrecht citizens speak about the Singels, referring to the walks along the water, surrounding the inner city. The singel park is a very popular walk for many residents and visitors of the inner city who enjoy the old trees, nice views, a rich bird life and, in spring, beautiful bulbous plants (Bals et al. 1988).

 

the Holland Water Line

The Lowlands provide an opportunity to use water for a common defence of the cities. The first chain of inundation areas, the so called Utrecht Water Line, was an improvised project in 1629, when the Dutch fought for their independence against the Spanish (Will, 2002:30). Later, this idea developed into a planned strategy that included the inundation of a network of polders ranging from Amsterdam to the southern branch of the River Rhine. Together, this network could protect the whole of Holland. In the late seventeenth century, the Republic built a chain of fortresses, sluices and inundation canals to make this system operational in case of emergency. This Old Holland Water Line was situated west of Utrecht and did not protect the city. Two centuries later, however, the New Holland Waterline included the defence of Utrecht by a series of inundation works and fortresses on the eastern side of the city. The first fortresses have been built from 1815 &endash; 1826. By the end of the century, improved cannons required defence works at a greater distance from the city and this led to a second chain of fortresses. For military reasons, the area with the fortresses in the eastern and north-eastern fringe of the city stayed green until 1948 (Will, 2002:124). Therefore, the city first expanded to the north and the west and it lasted until the 1960s before that urban growth took place on the eastern side. Here, building activities included two residential districts and the new university campus but the fortresses stayed green and became the carriers of the urban green structure. Because of their military function the public had no access to the fortifications and this contributed to their rich wildlife, as biologists discovered later (Maes, 1984: 27). In the last twenty years, some fortresses have been turned into public parks, whereas others are now protected areas.

 

Figure 4. The green structure of defence works.

Old fortresses and bulwarks are the carriers of green structure around the inner city and in the eastern part of the city.

 

 

2.4 The green structure of public parks

 

In the Middle Ages, the citizens of Utrecht could walk on the squares and courtyards of churches, monasteries and castles. These places used to be planted with elms and lime trees. After the Reformation also the cloisters opened their courtyards to the public and people could enjoy their herbs and fruit trees. Many of these public green spaces still exist in the inner city.

The first public recreation area originated in 1637. At the time, students of the university, which was founded the year before, liked to play a game with sticks and balls, the malie game (mall game). The council wanted to keep the city attractive for students and decided to create the Maliebaan, a one kilimetre long green alley with six rows of trees that was made for the game but soon became an attractive walk for many citizens (Bongers et al. 1988: 10).

It lasted until the late 19th century before municipal parks were felt to be a real need for the city. In 1888, inspired by the success of the singel walk around the inner city, the council decided to have a competition for a new public park east of the city centre. The result was the landscape-style Wilhelminapark, named after the queen in that period. This park became the attractive centre of the new developments between the working class districts and the urban fringe with the water line fortifications. Gradually, the establishment of public parks became a regular feature of urban development, and the first places chosen were old country estates with gardens that became part of the growing urban area. Between 1880 and 1940, six smaller country estates were turned into public parks and in 1962 the municipal council bought the larger estates Old and New Amelisweerd, forming a green area of 200 hectares stretching for almost three kilometres along the Kromme Rijn river. This park was to become the most popular of Utrecht's parks with well over a million visitors per year.

The next step in the history of urban green areas was the design of new parks as a part of new residential developments. The city has grown in a concentric way. The big medium-rise apartment-buildings of Kanaleneiland and Overvecht were built in the 1960s. In the 1970s and 80s a landscape oriented design resulted in the low rise Lunetten district. The river Leidsche Rijn has given its name to a big new urban district that is now under construction. Here, 30,000 new dwellings will be built and the same number of jobs created. Together, these districts generated a new generation of public parks. With the exeption of the Leidsche Rijn central park, most of these new green areas are islands of green. Until now, they are not connected by green ways.

Between 1950 and 2000 urban planners also further completed the green structure of rivers and fortifications, taking advantage of the opportunities in different parts of the city. One of these opportunities presented itself on the site of an old gasworks area along a river branch near the inner city. In the nineties, financial support made available for the clean-up of contaminated soils paved the way to create the Griftpark.

 

Figure 5. The green structure of public parks

Together, the public parks create a structure of spots rather than a network.

 

2.5 The green structure of transport networks

 

The construction of waterways, railways and motorways has had a major impact on green areas in the Utrecht area. Once the ships from Amsterdam went through Utrecht on their way to the east. The improvement of waterway connections between Amsterdam and Germany, however, led to the construction of the Merwede canal (opened in 1892). Half a century later, this canal had to be replaced by the larger Amsterdam-Rhine-Canal (opened in 1952). In the western part of Utrecht a section of the old canal survived. The canal banks provide a green way that is attractive for cyclists and pedestrians, but its technical design does not create interesting new habitats for wildlife. The railway verges demonstrate the opposite. They do offer excellent habitats and corridors that contribute to the ecological network. Cyclists, however, usually prefer other green ways. The motorway verges are not so special, whereas the motorways themselves create serious barriers between green areas and between the city and its surrounding landscape. In 1981, the construction of the A 27 motorway cut the Amelisweerd estate park in two and this event is seen by many as one of the tragedies of recent urban history.

 

Figure 6. The green structure of transport networks

Waterways and railways add new green ways to the existing green structure.

 

3. Green structure and urban ecology

 

This section first discusses the way urban green structure creates conditions for biodiversity. Then, there will be some remarks about health and recreation. Together, these issues represent the ultimate goals of green structure policy. Besides the urban ecology of goals, however, there is also the 'ecology of means' about the use of local resources for many cultural and economic qualities of urban life. In this context, the section discusses the management of water resources and the maintenance of green areas.

 

3.1 Green structure and biodiversity

 

biodiversity of Utrecht

Surveys in the 1970s revealed that the flora of the city of Utrecht and its immediate surroundings counts approximately 700 species of native plants, about half the total number for the Netherlands (Farjon et al. 1987: 77). Taking into account the presence of rare species in nature reserves in rural parts of the country, this number is high. In comparison with the 938 species found in a survey of the Province of Utrecht (approximately 2000 km2), the 700 of the city (nearly 100 km2) demonstrate the richness of the urban ecosystem (Provincie Utrecht, 1984:168).

The number of bird species breeding in the city is 93, of which 46 feel at home in the built-up area. Several groups of amateur biologists have collected data about other organisms, such as butterflies, amphibians and reptiles. These surveys do not cover the whole of the municipal territory, but they provide excellent information for the protection of these species and for the improvement of their habitats.

In different ways urban green structure creates conditions for biodiversity.

 

surface and use of green areas as a condition for biodiversity

A first condition is the surface of green areas. According to city statistics, the total territory of the Utrecht municipality is now approximately 100 km2. The built-up area covers about 70 % of this area, agricultural land takes 24%. Roads take 4 % and only 2 % is forest. These figures, however, do not say much about the opportunities for wild plants and animals. On the one hand, the built-up area figure hides parks, cemeteries, private gardens and street trees. On the other hand the figure for agricultural land refers to green house horticulture and other intensively used farmlands that do not offer any opportunity for wildlife at all. To describe the interesting habitats, we need other categories:

1. places with tolerated spontaneous plant growth such as: walls, derelict and fallow land, road verges, railway embankments and railway yards.

2. planted and cultivated areas like alleys, allotment gardens, sports fields, cemeteries, private gardens, parks and public gardens.

3. protected natural areas like fortresses, wet meadowlands, willow coppice and estate parks (Farjon et al. 1987: 78).

 

maintenance level categories and biodiversity

Within the public parks and gardens, the maintenance level of green areas is important. The green areas management department uses a typology of maintenance categories for public green areas that is shown in figure. 6.

Figure 6. Maintenance types of public green areas

 

Best conditions for wild plants and animals are found in the rough woodlands and rough grass categories. As maintenance costs are low for these areas, their surface increased in the 1980s, a period of budget cuttings. In residential districts these categories of green areas met with resistance. Wild was seen as the result of neglect and in socially problematic areas the wild bushes were soon perceived as unsafe. This led to a preference for higher maintenance levels within the districts. In areas between the districts, where the main green structure is concentrated. Here, it is therefore easier to create conditions for natural plant and animal life. Here we find the larger green areas where biodiversity can develop, not because of neglect or budget cuttings but as a result of ecological maintenance practice.

 

ecological corridors and biodiversity

Connecting corridors between green areas are vital for crawling animals and for the dispersion of seeds they carry with them. The role of green corridors therefore has become an important issue for urban ecologists. In their preparatory study of the Utrecht Green Structure Plan Farjon et al. 1987: 87. point at the following dispersion zones requiring attention in planning and maintenance: 1. river zones of Kromme Rijn, Leidsche Rijn and Vecht and adjacent green areas; 2. railways and adjacent areas; 3. water courses with unpolluted water; 4. ecological corridors situated along pedestrian and cycle tracks in gradient areas between different soil types and 5. a zone along the Amsterdam-Rhine-Canal that is used by migrating animals in north-south direction. All of these corridors are linked to the main urban green structure. The regional authority of the Province of Utrecht established a method of biotopes and ecological groups with a guiding organism as a basis for ecological corridor planning (Van Arkel et al. 1993: 95). The municipal green areas department further elaborated this approach and generated maps for six ecological groups, indicating the desired corridors and a number of activities to remove constraints and improve conditions (Oost et al. 1999: 39).

 

abiotic conditions for biodiversity

Corridors only create ecological conditions for biodiversity if they connect habitats. Habitat qualities related to abiotic factors like soils, ground water and surface water play a key role in this context. Gradients at the landscape level between high and low, dry and wet, sand and clay, create a frame for diversity. One of the key factors is upward seepage of groundwater in the north-eastern part of the city where the sandy soils of the Utrecht Hill ridge are covered by thin layers of clay and peat. This area is a potential source of clean, nutrient poor water.

Interesting gradients at the scale of railway verges have been introduced by the use of nutrient poor sand for construction. Nutrient rich is the dominant feature of the urban environment and of the agricultural land on the clay and peat soils around the city. Therefore nutrient poor introduces ecologically interesting gradients.

The gradient between dry and wet conditions on each riverbank and along all other surface waters asks for detailed design and nature friendly banks therefore have become a regular part of habitat creation programmes in all parts of Utrecht.

green structure as a basis for present and future biodiversity

Most of the above mentioned ecological conditions may enhance biodiversity if they are made manifest in the green structure levels discussed in section 2: the rivers, the defence works around the inner city and in the urban fringe, the larger parks and the railway tracks. This implies that the urban green structure creates the vital conditions for the preservation and development of biodiversity.

 

3.2 Green structure, health and pests

Research about the use of green areas in Utrecht revealed that 65-86 % of the residents of different urban districts frequently visits a park and 67-87% frequently visits a recreation area outside the city (Hinssen 1993: 27). The Wilhelminapark in the city and Amelisweerd, just outside the city, both attract approximately one million visitors per year. The inner city parks and the outer green areas are not exchangeable (Hinssen 1993: 24). People love them for different reasons. A direct cause and effect relationship between the presence of green areas and human health is difficult to prove but in general terms the healthy effect of outdoor activities in green areas is clear (Van den Berg & van den Berg 2001).

The history of the Griftpark is a paradox in this context. The highly contaminated soil of the old gasworks could not be completely purified. Therefore the area was considered too unhealthy for residential development. As a result, a beautiful park emerged in the heart of the city: unhealthy in case you would grow fruit trees and eat the apples; very healthy, however, for the stressed office workers looking for a quiet park to have their lunch.

Recently Van Bronswijk (1999) pointed at the risk that more natural ecosystems in urban areas could improve conditions for rats and mosquito's. She even warned for a possible revival of Malaria as a result of climatic change combined with the presence of natural wetlands in Dutch cities. The reaction from experts in the fields of entomology, epidemic and tropical diseases was clear: there is no evidence of such a threat (Takken et al. 1999: 836). The opposite is more likely. If green structure is to be developed for a number of activities, than, investment in environmental measures to improve water quality is a logical step. Thus, in the last twenty years, Utrecht invested in the connection to the sewer system of old houses along the Oude Gracht, the central green and water axis through the city. As a result, there was a remarkable increase of oxygen in the water and this, off course, contributed to all the activities related to the Oude Gracht system.

 

3.3 Urban water and climate

More natural ecosystems can also play their role in improving water quality and the introduction of the wetlands as a part of the urban water system is a good illustration of this ecology of means. Here it is not an ecological goal like biodiversity that asks for means, but it is the multifunctional goal of creating good water quality that asks for ecological means. The new Leidsche Rijn development will have a surface water system in which water circulates from the built-up area into a lake in the adjacent green lobe that is part of the urban green structure. Here, the water will pass through the wetland that will care for sedimentation and nutrient uptake. The purified water will then recirculate into the built-up zone (Spangenberg, 1995).

The role of green areas and street trees in moderating urban climate is clear in general terms, but apart from some incidental discussions about the need for a windbreak for cyclists, climate is not an issue in Utrecht, nor in other Dutch cities.

 

3.4 Use of green resources

In the built-up area of Utrecht approximately 150 hectares of green area are being used as allotment gardens. Agriculture, most of all dairy farming on meadowland, used to be the dominant land use of the green areas around the city. In 1985 there were still 47 farms, but many of them were small hobby farms with part time farmers (Wieringa, 1987: 19).

Full-time farmers increasingly face the need to industrialise and expand their enterprise and this is extremely difficult in the urban fringe that is full of uncertainties about urban expansion. Several zones in the western and eastern Utrecht fringe area are not yet urban and no more rural.

The process of urbanisation is more than the building activities. In recent years, the rural perspective of a landscape produced by agriculture changed into an urban perspective where planners and politicians speak about urban landscape consumers who have their preference for green area quality. In this process of change the economic question is whether these new consumers are really prepared to pay for the green landscape they enjoy. Can the Green Heart become a Central Park?

One approach is the Noorderpark, a 5,700 ha rural area just north of the city. The area is part of the Randstad Green Stucture scheme that aimed at creating larger green recreation areas situated between the agglomerations of the Randstad Holland (van der Cammen & de Klerk, 1986:304). It was this planning document that introduced the term Green Structure to the Dutch spatial planning vocabulary in the 1980s. The Randstad Green Structure Scheme has a project budget and operates under the legislation of the 1975 Relation Memorandum rules that deal with payment for farmers who fulfil landscape maintenance tasks.

A different approach is chosen for the Amelisweerd area, where the municipality owns the land and leases it out to local farmers. In this way the landscape can keep its qualities for human visitors and for wildlife, and at the same time its resources are used by farmers.

 

3.5 Surveys and monitoring

Utrecht has a long tradition of experts who have initiated important ecological studies about nature in the city. A working group of amateur ecologists - with the long name Working Group for the Restoration of the Quality of Life in the Old Districts of Utrecht - explored the ecological treasures of the city in the seventies and eighties. They published detailed studies about green areas in and around the city (Werkgroep Herstel leefbaarheid Oude Stadswijken Utrecht, 1997; Ministry of CRM, 1982, Maes, 1984). In the preparation of the 1990 Green Structure Plan, Farjon, Harms and Scheffer (1987) carried out the first systematic analysis of present and potential plant and animal life in the city. In the 1990s, the focal point of green structure planning shifted towards improving and establishing ecological corridors. This political priority stimulated a number of studies that concentrated on opportunities and threats to ecological pathways (Oost et al. 1999). The resulting project implementation plan (Gemeente Utrecht, 1977) included a monitoring task per project. This will lead to a better understanding of the impacts of interventions and maintenance practices. The municipal department has no staff to do systematic surveys, but private organisations are very active in parts of the city. This is the case of the group that has taken care of maintenance and monitoring of the Bloeyendaal park on the east side of the city.

Prior to every major building or construction project the green areas department carries out an ecological survey.

 

4. Green structure planning in Utrecht

This section reports about a special case study on Green Structure Planning. It starts with a description of the planning issues. Then the 1990 Utrecht Green Structure Plan will be analysed and the final part discusses the issues in a wider perspective.

 

4.1 Green Structure Planning

 

the issues

In the Netherlands, Green Structure Plans (GSPs) emerged in the 1980s as a sectoral planning instrument used by municipal parks and green areas departments. Previously, urban parks, woodlands and graveyards had been treated independently as separate areas and policy documents on open spaces concentrated on the quantity and distribution of the city's green areas. The new approach introduced by GSPs treats these areas as a coherent green network and emphasises their quality and structure. At the end of the 1980s the ministries responsible for urban green areas and urban development jointly published a brochure that defined the Green Structure Plan as follows. "A coherent package of objectives, principles and priorities for the desired quality of green areas in the public domain throughout the whole municipal territory, leading to proposals for sustainable development, with agreements about shared responsibility and finances." (Meeus, 1989). Clearly, the GSP is a strategic plan based on a consensus on the main policy direction. The strategic plan aims to structure and guide the development of operational plans for concrete physical interventions in the urban landscape.

Several issues contributed to the emergence of this structural approach to green area planning, each leading to hypotheses about the role of green structure planning as a tool. This paper explores and discusses the questions arising from these hypotheses.

The first issue is whether green structure planning is a tool for defence or integration. Increased competition for land within the cities and in urbanising regions creates conflict, which is described as a battle between red and green. Private and public actors in the fields of housing, commercial development and public buildings &endash; the red functions &endash; tend to dominate at the expense of the green functions such as agriculture, forestry, recreation and nature conservation. Actors in the green sector consider themselves to be the weaker party and feel the need for defensive or even offensive strategies. The hypothesis is that GSPs will strengthen the role of green areas in urban development because they provide a structure for the network of green areas. The question is whether the tool operates as a defensive tool &endash; or possibly even an offensive tool &endash; or that planners use it as an instrument for integrating green areas into urban development. This leads to the second issue, the potential synergy between green area planning and other fields of planning.

The second issue concerns ecological networks, traffic and water. Since the early 1980s, biologists have stressed the importance of ecological networks of habitats, corridors and stepping stones for the survival of wild species, and these networks have become the cornerstones of nature policy at the national and regional level. The hypothesis is that GSPs can help to bring nature back into the heart of the city. In a reaction to the domination of the car in urban development, pressure is growing to develop networks of routes for pedestrians and cyclists. Riverside parks and other linear green areas provide a natural basis for these greenways in the urban landscape. The hypothesis is that green structure planning and the planning of walkways, cycle paths and bridle paths are natural allies. In the field of water management, valleys and river floodplains play an important role in stormwater storage and flood prevention and in many cities these areas are already part of the existing green structure. The hypothesis, therefore, is that it will be easy to develop joint strategies for water planning and green structure planning. The question is how a GSP creates links with planning for nature, water and traffic and how this influences the role of green areas in urban development.

The third issue concerns strategies and budgets. One of the reasons for making GSPs is the perceived weak position of green functions in budgetary negotiations. In contrast to buildings, green areas rarely generate direct profits for private investors and public sector investment in green areas can be a risky business, too, because cities rely on the income they can obtain from selling real estate to developers. In periods of economic downturn or recession, as experienced in the 1980s in the Netherlands, budgets for creating and maintaining green spaces shrink. The hypothesis is that a GSP lists the priorities for survival in times of financial difficulty because it defines the backbone of the city's green areas. The question is how GSPs are linked to investment strategies and maintenance budgets.

This leads to the fourth issue, that of structure planning and projects: the links between the strategic GSP and operational projects. Individual green area projects may not form a coherent whole; the essence of a GSP is to reach a consensus on the creation of a coherent structure of urban green areas. However, strategic plans such as GSPs tend to be rather vague and may not lead to action on the ground. The hypothesis is that a GSP will improve the conditions for developing a coherent package of projects. The question is how a GSP can perform the critical role of building bridges between a strategy and actual projects.

 

approach of the case study and

The Utrecht case study that forms the basis for this paper resulted from the author's involvement as a researcher and consultant in several projects in Utrecht (de Jong et al., 1992; Tjallingii et al., 1995). The analysis of green structure planning in Utrecht is based partly on a more recent case study carried out as part of the GREENSCOM project, an EU Fifth Framework research project (Aalbers et al., 2002). The picture was completed by a literature study and interviews with key actors. Utrecht is an interesting case for explorative research into the role of green structure plans. Firstly, because the battle between red and green has at times been dramatic at times. Secondly, because the city made its GSP in the late eighties and followed this up with a series of other strategic and operational plans, which makes it possible to analyse the impact of the planning instrument over a period of time.

In general terms, the analysis fits in with the methodology for case study research described by Yin (1994). As a GSP is a strategic plan, it only provides guidance for subsequent operational plans. This implies that a GSP case study requires a format that differs in some respects from the outline suggested for operational plans by Francis (2001:20).

Section two describes the main features of landscape and urban development in Utrecht and the planning history of the GSP. Against this background, section three places the issues and hypotheses in a wider perspective. The concluding discussion argues that the problems do not require defensive or offensive strategies but rather an integrated approach.

 

Figure 7. The 1990 Utrecht Green Structure Plan.

The map shows many green structures as the different layers represented in the figures 2 &endash; 6 are brought together in one map with planning information. Dotted lines indicate planned greenways.

 

Figure 8. The Singel Restoration Project

From left to right: The logo of the project; the map showing the missing link in the Singel green structure; the cross section design; a part of the singel after reconstruction.

 

 

4.2 The Utrecht green structure planning experience

 

the context of landscape and urban development in the Utrecht area

The city of Utrecht has approximately 250,000 inhabitants in an area of 91 km2. The Utrecht urban region has more than half a million inhabitants and is a part of the Randstad Holland metropolitan area.

Utrecht is a river city. The Romans founded the city at a point where they could cross the river Rhine. The main channel of the Rhine now lies further south and the remaining Kromme Rijn is only a small river. It meanders through the city, where it divides to form the river Vecht, which flows north, and the Leidsche Rijn, which flows to the west. The land to the west and north of the city consists of meadows on peaty soils, to the north-east lies a Pleistocene sand ridge covered by woodland and suburbs. But it is the river that shapes the urban street pattern and green structure. Like many Dutch towns, the inner city is surrounded by water and old fortifications. In the nineteenth century these were transformed into a narrow park and walkway, called the Singel, which is now an important element in the urban green structure. In the late nineteenth and twentieth century, the green structure has been further enriched by a number of public parks. To the west of the city centre, the map of Utrecht also shows the old and the new shipping canals, that link Amsterdam to the Rhine.

The city has grown in a concentric way. The Leidsche Rijn river to the west has given its name to the latest large new urban extension now under construction. This new district will contain 30,000 dwellings and there will be space for industrial estates that can create the same number of jobs.

Given its central position in the country, Utrecht has become an important road and railway junction. The green planners and many residents suffered a traumatic experience when, in the early 1980s and after a battle of more than ten years, a new motorway was built to the east of the city, cutting right through the woodland of the popular Amelisweerd estate. Here, indeed, urban development was the enemy of nature. Another major project that deeply divided the community was the enormous Hoog Catharijne shopping centre. A huge area of the existing city and part of the beautiful Singel had to give way to dynamic modern life. This turned out to be so dynamic that just thirty years later this megaproject already faces a megachange. Paradoxically, plans for the new project include excavating the part of the Singel that had previously been filled in.

 

the 1990 Green Structure Plan: defence or integration?

The Utrecht Green Structure Plan for the city was published in 1990. Figure 1 shows part of the GSP map. The green areas department launched the GSP as a sector document; other municipal departments played only a marginal role in its development. In the introduction to the GSP the authors mention the alarming economic situation as the main reason for publishing the plan (Gemeente Utrecht, 1990:4). The plan applies standards for the minimum amount of green area in square meter per person to describe the shortages and surpluses of green areas in different parts of the city. Given the difficult financial situation, the plan proposes overcoming the shortage in some districts by improving connections to existing green areas, especially for cyclists and pedestrians.

A defensive attitude was also adopted in discussions with the regional planners. The GSP argues for a green belt around the city to contain urban development, but the provincial planners were in favour of a lobe structure of urban expansion interspersed with green wedges (Gemeente Utrecht, 1990: 46).

Following the efforts to quantify the surplus and shortage of green areas in the GSP, the green areas department commissioned new studies to quantify the value of green spaces (Hinssen, 1992). Further studies (Gemeente Utrecht, 2000) tried to collect quantitative data on the demand for green spaces of different qualities and sizes in the Utrecht area, but these methods have still not been operationalised. Moreover, focusing on hard figures to underpin the sector's interests did not create a climate of cooperation with other departments.

 

potential synergy: ecological networks, traffic and water

Although other departments of the municipal council have formally referred to the GSP, there have been no significant joint planning efforts. Opportunities for synergy between other planning activities and green structure planning, for example with the Bicycle Memorandum (1992), the Memorandum on Sustainable Building (1993) and the second Environmental Policy Plan (1993), were lost. The spatial planners, though, did do justice to the GSP by explicitly mentioning in their 1995 Spatial Structure Vision that "the green structure should be improved by making the surrounding landscape more accessible from the city" (Gemeente Utrecht, 1995: 17). The realisation of the Utrecht bicycle network was certainly aided by these supportive policy plans.

Efforts to combine the green structure and the water structure have been less successful. A study initiated by external consultants proposed the creation of a coherent water and green structure linking the city to the upstream Kromme Rijn landscape and giving green spaces an important role in rainwater retention (de Jong et al., 1992). These ideas met with scepticism among the provincial and municipal water officials, who were not prepared to relinquish their traditional view that quick removal is the best way to deal with rainwater in urban areas. The green areas department itself made more specific recommendations on water management in their 1995 report on the options for the sustainable management of public open spaces (Tjallingii et al., 1995: 56). At that time, the recommendations were shelved. A few years later the water management officials finally came round to the idea, but by then the green areas department had already adopted another theme: biodiversity, or urban nature.

In 1998, the green areas department published a Policy Framework for Urban Nature (Gemeente Utrecht, 1998) which introduced urban nature as the overarching principle of green structure planning. The 1990 GSP had hardly mentioned ecological corridors, but now the policy makers started to define the green structure as the spatial structure of the Ecological Network (Gemeente Utrecht, 2000:4). The successful policy for the National Ecological Network, launched in 1990 by the Ministry of Agriculture, Nature Management and Fisheries (Ministerie LNV, 1990), proposes corridors and stepping stones to allow plant and animal species to migrate between habitats. A few years later, the provincial authorities drew up plans for the regional network (Provincie Utrecht, 1993) and the municipal council followed suit. As the local ecological network became the key issue, green structure planning became more sectoral than ever. Surprisingly, but also logically, green structure planning, for the first time, began to adopt an offensive role.

 

financial basis: strategies and budgets

The strategic 1990 Green Structure Plan, which was intended only to create a framework for concrete operational projects, had no budget allocation and depended on other programmes for the realisation of its proposals. This was not uncommon for strategic plans, but in the years that followed the weakness of this construction became apparent. In the 1990s the economy picked up again and the municipality managed to fund a sound implementation programme for green areas and linked this to the 1998 Policy Framework for Urban Nature. Later, the government ministries responsible for green areas and urban planning launched a joint investment programme for green areas in and around the cities as part of the national urban renewal programme (Ministerie LNV & Ministerie VROM, 1999). This further encouraged the parties involved in green areas in Utrecht to cooperate (Gemeente Utrecht, 2000).

Maintenance budgets, too, benefited from the favourable economic climate, and committed and active residents also helped to maintain green areas. At the neighbourhood level, the city council introduced maintenance contracts between the municipality and groups of residents (Aalbers, et al. 2002:58). Currently there are about 600 of these contracts, under which residents do the work and the municipality provides a modest budget, practical support and advice. These contracts are a product of the district-oriented approach that has evolved in many Dutch cities since the 1980s.

 

green structure planning and green projects

In the early 1990s, the GSP did not play an active role in creating suitable conditions for project implementation. Nevertheless, Utrecht has realised some spectacular green projects during the last ten years. One of these is the Griftpark, the site of an old gasworks near the city centre, which has been converted into a beautiful park. A brownfield changed into a green area. National funds from soil remediation programmes provided the bulk of the huge sum required to transform this derelict land into a healthy park.

Another fine example of a green project in the heart of the city is the Singel restoration project mentioned above. The project description does not mention the Green Structure Plan, but the project website includes the GSP map, which illustrates a convincing argument for restoring the missing link in the Singel (see Figure 2).

A larger&endash;scale project is the masterplan for the new Leidsche Rijn urban extension, which is evidence of a revival of integrated green structure planning (Spangenberg, 1995). The multidisciplinary project team for the new development emphasised sustainable urban development issues and gave green areas an important role in the design for the new urban area. The centrally located park is connected to the urban fringe and an old country estate by green fingers that reach out between the neighbourhoods. The close relationship between landscape and water planning became a landmark in this emerging field of planning.

More recently, local government officials have started to use the updated green structure map in negotiations with national and regional governments on funding new green areas and regenerating existing areas (Gemeente Utrecht, 2000).

 

 

4.3 Discussion

 

defence or integration

The Utrecht case illustrates the shift in attention from individual green areas to green networks. The change of emphasis towards spatial green networks is a general trend among the 18 Dutch municipal GSPs included in a survey by Meeus et al. (1989). This trend is not limited to the Netherlands; a similar change was found in the approach to the green zones central to the transformation of the German Ruhr area (IBA Emscherpark, 1992). Turner (1992) demonstrates the same trend in the plans for green open space in London and describes it as a shift from standards per 1000 (inhabitants) to green strategy. Previous reports, he argues, have focused on the quantity and distribution of open space. In the new approach the emphasis is on the quality of open space and on its structural role (Turner, 1992: 385). Obviously, the authors of the Utrecht GSP were reluctant to point to the spatial structures themselves as an indication of the value of green spaces and commissioned further research to quantify their value. This may be a reflection of the defensive attitude that dominates the GSP. Repeatedly, the GSP text speaks of "protecting green areas from urbanisation as far as possible" (Gemeente Utrecht, 1990: 7). Even in recent interviews, planning officers from the green areas department are sceptical and defensive: "Although the importance of green areas in urban situations is recognised, other interests often play a more important role" (Aalbers et al. 2002: 98). The 1998 Policy Framework for Urban Nature formally requires planners to refer all building proposals in green structure areas to the city council. Citizens may legally challenge the council decisions. On five occasions since 1998, the courts have allowed the council to build on this land. According to department officials, the potential value of this policy is uncertain.

It is interesting to compare the Utrecht case with Breda, a city where green structure planning has played an important role since the early 1980s. The Breda story illustrates a strategic planning approach that started with the GSP and succeeded in giving a prominent role to green areas in an integrated approach to planning urban projects (Verburg et al.,1994; Tjallingii, 1995: 125). In the Utrecht situation both the Leidsche Rijn development and the Singel project confirm the potential value of the GSP as a tool for integration. This shows that a GSP, as proposed in the first hypothesis, can act as a tool for strengthening the role of green areas in urban planning. However, it seems as if the tool performs best if it is not used in a narrow, defensive way, but in a more open process to facilitate cooperation and integration between green and red.

 

ecological networks, traffic and water

The Utrecht case confirms the hypothesis that the GSP tool has the potential to bring nature back into the heart of the city. The Utrecht planners felt the need to develop additional tools to achieve this goal: a Policy Framework for Urban Nature and an implementation programme with an annual budget. The Utrecht case also illustrates that green structure planning and the planning of pedestrian and bicycle routes are natural allies. The 1990 GSP explicitly refers to this combination, but apparently the plan did not play a prominent role in the realisation of concrete greenway projects. Although the hypothesis on joint strategies for green structure and water planning is not supported by the experience of the past decade, it seems that the Utrecht planners were just late in discovering the potential of combined green and water strategies. Other Dutch cities, for example Breda and Drachten (Tjallingii, 1996: 114, 256), had taken the lead, but after the successful Leidsche Rijn planning experience Utrecht joined the pioneers in this field.

From a wider perspective, nature and ecology are ambiguous concepts in planning terms. On the one hand there is a concrete but narrow object-oriented approach aimed at species and nature reserves. On the other hand, there is a broad process-oriented approach to ecology and planning. The Strategy of the Two Networks (Tjallingii, 2000:104) uses ecological processes related to water and traffic in a tool for integrated urban planning. One implication is that green and red are no longer considered to be enemies because both are seen as part of the urban ecosystem.

The dialogue between object-oriented and process-oriented ecology in urban planning is an international issue. In his study of Scottsdale, Arizona, for example, Cook (2000) positions himself as an object-oriented planner of ecological networks for certain species. Turner (1998:137) looks at greenways in a broad ecological way that is akin to the process approach of Michael Hough (1984, 1995). Experiences in Dutch cities suggest that a broad process approach creates good general ecological conditions for urban life that may be further developed for use in concrete species-oriented plans. Starting with plans for individual species, however, does not necessarily lead to good general conditions for urban planning.

strategies and budgets

The Utrecht experience only partially supports the hypothesis that a GSP sets the priorities for the survival of green areas when budgets come under pressure. Although the municipal council adopted the final document, the GSP was a product of one department and so it did not reflect a broad consensus on priorities. Moreover, the weak connection with financial planning has been a major flaw of the GSP, especially in the first few years.

There are other options for combining green structure planning and financial planning, as demonstrated by the principle of give and take in the Breda GSP (Verburg et al. 1994: 270). This implied that in neighbourhoods with a lot of green areas some public green could be turned into private green or even into red. The GSP included the agreement that the Parks Department itself could use the money generated in this way to improve the quality of green areas in other places. This gave the Parks Department the means to invest in the main green network, even in a period of severe budgetary constraint.

In Utrecht, the link between green structure planning and financial planning became much stronger after the 1998 Policy Framework for Urban Nature. The updated green structure map guided negotiations between the local, provincial and national governments on investment in green areas.

The relationship between spatial plans and investment is an emerging theme. Traditionally, spatial planners have only had communicative and regulative tools at their disposal to provide a framework for investment by other parties. Hajer & Zonneveld (2000: 339) argue for a rethinking of the detached, coordinative role of spatial planners. The Utrecht case study illustrates that what is discussed at the national planning level is already being put into practice at the local level. But at both levels the relevant question is about the choice between sectoral projects or integrated projects. In both new and existing urban districts it may be obvious for local authorities to initiate projects that integrate red and green, but Dutch municipalities do not have many financial resources of their own. In this situation, support from national sectoral ministries is vital for local integrated projects.

 

structure planning and projects

The hypothesis here is that the GSP will improve the conditions for a coherent package of projects. The Utrecht case study shows that the 1990 GSP can indeed be seen as a step towards a coherent view of the connections between green areas. It took a second round of green structure planning to establish a clear link between this perspective and a programme for project implementation. However, the Policy Framework for Urban Nature that resulted from this second round became more sectoral, with a narrow ecological orientation. It gained strength but lost the wider perspective.

Again, the comparison with the Breda case is illuminating. In the Breda case, green structure planning became an instrument for the emancipation of the green sector and gradually led to the creation of a fruitful climate of cooperation. A broad team of committed politicians and officials from different departments realised a wide range of integrated projects for sustainable urban development. These projects combine water and traffic issues with new habitats for wildlife and other aspects. In 2002, for the third time in three years, Breda won the sustainable city award, a competition between 300 Dutch municipalities. This demonstrates the city's structural commitment to the issues that were put on the agenda by the Green Structure Plan and other strategic documents almost twenty years ago.

 

enemies or allies

The discussion about green structure planning, illustrated by the Utrecht case, demonstrates the limited impact of defensive approaches. Offensive strategies that combine spatial planning with investment strategies may be more fruitful. However, the best approach to the problems and challenges of urban areas is not a defensive or offensive strategy for limited issues, but an integrated approach. There is much to be gained by making creative use of the opportunities that present themselves if green structure planning joins forces with planning for nature, greenways and water in the city. In doing so, green structure planners can focus on contributing to the quality of the built environment, rather than fighting a battle between green and red.

 

 

Acknowledgement

The author is greatly indebted to Carmen Aalbers, Tamara Ekamper, Peter Schildwacht and Arno van den Hurk for their valuable comments on the draft version of this paper.

 

 

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Websites:

www.breda.nl

www.utrecht.nl/ herstel singelstructuur utrecht

www.groenstructuurplan.nl

 

 

 

 

 

 

Working Group 1A - Comparison of Case Studies

Bibliography

Other papers relating to people/ ecology interface

Warsaw

Vienna

Munich

Oslo

Belgium - benefits for people

Sheffield to do

Helsinki

Utrecht

Herning

Ceské Budejovice

Comparison of case studies

UK - benefits of nature

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