Working Group 1A - Comparison of Case Studies


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Case study Oslo - Draft 1.

©Signe Nyhuus, Department for Environmental Affairs and Transport, Municipality og Oslo, 2002



The municipality of Oslo (454 km2) is located in the inner part of the Oslo Fjord in South Eastern Norway (59'55 N, 10'45 E). Approximately 2/3 (307 km2) of the municipality is covered by forest, waterways and agricultural land and 1/3 (147 km2) by a building zone that includes residential, commercial and industrial areas. Approximately 30 km2 or about 20% of the building zone is covered by mixed boreal forest and deciduous trees. The municipality employs approximately 42 000 people and consists of around 70 different agencies. Since 1995 Oslo has been the fastest growing city of the Nordic countries with the creation of 69.000 places of work and an imigration of 46.000 people to the city (the figures escribes the periode 1995-2000).

Compared to its surroundings the local climate in the city is dominated by relatively warm summers, low precipitation and mild winters with the city itself located in a south-facing valley. The terrain slopes gently upwards from sea to the forested hills around the city (300-700 meters above sea level). The inner Oslo Fjord belongs to the Oslo region. Cambro-Silurian limestone and shales, rich in calcium, folded in the Caledonian era, make up the central parts of the city and westwards along the fjord. The Oslo region is a result of an extended depression of earth covered by sea and slowly filled with sediments. The age of the rocks varies from Cambrian to Permian (600-250 million year ago). Remnants of the Pre-Cambrian rock, mainly of gneiss and granite, are exposed in the southern and eastern part the municipality (Dons 1996, Holtedahl and Dons 1957).


1. How have natural and cultural factors influenced the development of greenstructure in the urban environment?


New archaeological findings date the city back to year 1000 and for that reason Oslo celebrated its 1000 anniversary in the year of 2000. Back then the natural landscape was strongly influenced by the outlets of 9 rivers in a distance of just some few kilometres in the inner part of the Oslo fjord. The river basin was relatively flat covered by lush deciduous vegetation and the biodiversity must have been very high. On three sides the landscape rose up to 300-700 meters and vegetation shifting to coniferous forest, spruce in the north and west and pine in the east and south. Since the river basin soil was so rich due to marine sediments there were many small farms both inside and around the town. This had some influence on the natural landscape and vegetation and so had the monisteries that were settled in the town and on one of the islands in the inner part of the fiord. Many species were introduced to the excisting flora and some of them still remains here today even as red listed species.

The town was first located around the outlet of the Alna river and consisted merely of wooden houses. The streets were narrow and the fires were many. In 1624 one of the worst fires in the history took place. After that King Christian the 4th decided to move the city to Akershus'back yard both in order to protect it from the attackers and to construct a new city built of stone. From there the city expanded to the size it has today. Figure 1 shows the development of the urban sprawl in Oslo for the last two centuries. The natural vegetation in and around the city was slowely transfered to gardens and cultivated parks and the last two centuries rivers have been canalised underground. Today approximately 60 % of the 283 kilometres of water corridors are canalised underground.

Most of the urban development has taken place after the second world war. The social democratic government in charge right after the end of the war had one slogan: Urban and rural hand in hand. This was an efficient methode of looking at the country as a hole. For the farmers it ment among other things that they had to leave a lot of agricultural land near the biggest cities to new towns. Some of the suburban areas in Oslo are built on some of the best agricultural land in the country (Groruddalen, Bøler). However soil protection became an important issue during the sixties and seventies and so the suburban areas from the seventies are built on bedrock (Romsås, Søndre Nordstrand).

The built up area of Oslo is still one of Europe's least densely populated and the rate of development today is, according to some politicians, not high enough in order to meet the rising demand for housing. The pressure on the greenstructure within the built-up area is however strong due to the preservation of the forested area surrounding the building zone but lying within the municipal border. The region areound the municipality of Oslo consists of about 6-7 municipalities. Most of these are more liberal concerning development on virgin land because they want to keep the countryside character as a contrast to the city. The consequence of this politics is however that recreational areas in the neighbour communities dissapear.

A large part of the population of Oslo are used to live in green surroundings and the awareness of the greeenstructure being threatened has just been wakened the last 20 years. An analysis of the reduction of greenstructure in Oslo from 1952-1990 revealed a significant impact on three categories of greenstructure due to land use changes from natural areas to residential, commercial and industrial space (Guttu et al. 1997). The same study found that there has been a strong fragmentation of areas, on average a 50 % reduction from 1950-1990, which resulted in more, but smaller areas of green open spaces. The same trend could be anticipated to take place from 1990 to the present day, but the introduction of the Green Plan (Oslo Municipality 1993) and the Green Chart (Oslo Municipality 1997) are actions that hopefully alter this development.

A comparative study of several European cities (Oslo, Stockholm, Copenhagen, Helsinki, den Haag, Bristol, Birmingham, Hannover, Gdansk, Zaragosa) carried out by the University of Oslo on the inquiry from the Municipalty, shows that Oslo was largest in area, but had only 27 % of the area developed. The rest was forests and greenstructure

The separation between the forest and development area has been on the agenda for many years. Politicians decided many decades ago that all new development should take place within a border between the forested area and the area that was defined as the built-up area. This border has stayed the same since then even though new politicians now and then have suggested to built on virgin land (Marka) outside the border. Figure 2 shows a map of the municipality showing the situation. The vegetation/forest type and the management in Marka differ very much from the vegetation types and management within the built-up area. However both types are multifunctional.

Along with the reduction of greenstructure follows higher pressure on remaining areas. Wear and tear increases as well as the need for more detailed and skilled management. Oslo has become a multicultural city during the last 20 years. Today different cultures use the green open spaces differently but the local knowledge is so far too low in order to develop a management system that includes these aspects.

Another feature of the planning procedure in Oslo is a high degree of private planning where private initiatives develop zoning plans for approval by the Building and Planning Authority where a lack of biodiversity information may unknowingly lead to loss of natural vegetation and habitat fragmentation. Being multifunctional greenstructure demands a multi professional planning strategy and management.


2. What does this greenstructure mean for biodiversity, environmental sevices and management of flows?


Table 1 shows different land use and greenspace categories within the build-up area of the

municipality. The category forest in the table means a mix between pine and decidous

trees, Ulmus glabra being the most common followed by Tilia cordata and Pinus sylvestris.



Due to a mild local climate, calcium-rich soil, varied topography and a short gradient between sea level and the surrounding boreal forests, the city of Oslo is very rich in biodiversity in relation to its location and latitude. The different naturetypes recorded in the municipality is shown in figure x. The richest biotopes of natural vegetation are on the Cambro-Silurian layers up to approximately 220 meters above sea level. Furthermore, Oslo has an international responsibility for these biotopes due to the very specialised vegetation (rich broad-leaved deciduous forest, calcaerous woodland and calcaerous rocky shores), species richness and the high number of red-listed species. This vegetation is uniquely found in the building zone and on the islands and the need for preservation and in some cases management becomes even more urgent since these vegetation types are not found in the forested areas outside the building zone.

Biodiversity in Oslo is located in the forest (Marka), within the greenstructure of the built up area, in the building zone in general and in and around sweet and salt water. Figure x shows the main distribution of the overall habitat types in the municipality. Most of the biodiversity is found in these and other habitats and only some very few species (birds) are dependent on the urban construction itself. Two main features of the greenstructure is highly important: the size of the open spaces and the quality and management of them.

Figure 1. The share of some main habitat categories in the municipality of Oslo.

Figure 2. The recorded habitats in Oslo are classified according to national High/Low Importance classification criterias. The diagramme shows that the different importance classes contain about the same share of habitats.

Environmental services:

For recreational purposes Oslo provides good access to green open spaces for people to use within the built up area. European Common Indiactor number 4 asks for access to green areas within 300 meters from the recidence. 95% has access when considering all areas regardless of size while 89% has access to an area larger than 10000m2 within 300 meters from their residence. So far the indicator does not regard the quality of the green open spaces that are accessable. The information has been handed over to the City Districts and it is up to them to analyse their greenstructure in detail. 10 Districts have elaborated a Green Chart which is a very useful tool.

The report "Ecological land use principles for the built up area of Oslo 1991" explores a network of small green areas that fuction as noise reducing and/or pollution reducing elements in the city. Some of these still excist and some have been developed during the densification periode of the ninties. Oslo is still a very green city but there is now a rising awareness of the functions of these small open spaces. Schools and kindergardens have started to adopt "100 yard woods" in their neighbourhood. In order to get the



Figure 3. Map showing green areas within the building zone available for people 300 meters from the house they live in.

Environmental certificate "Environmental Lighthouse" (an official Norwegian environmental certification for small and medium sized private and public businesses) one of the demands is to adopt such an area in their pedagogical system and practical teaching.

Several analysis concerning air quality and corridors for ventilation have been carried out during the last 15 years. Stations monitoring air quality and pollution are located on strategic places according to the results of these analysis. Limited studies in inner city districts with low environmental qualities has resulted in replacing a kindergarden when stagnation of low quality air was identyfied. Despite that, in large development projects decisions have been taken in opposition to recommendations with bad consequences for local air quality. For Oslo this is especially bad because of the natural landscape features. During winter days with high pressure and no wind air will stagnate in the "pot-shaped" landscape. The increasing focus on possibilities to re-open parts of the rivers and brooks running through the urban landscape could lead to a better flow also for winds in the city.



Management of flows:

60% of the rivers running through Oslo are canalised underground. When the last city government came in office they had two main environmental tasks on the agenda. One was to strengthen public transportation, the other was to restore the blue-greenstructure of the city. About 10 years ago the biggest river in Oslo, Akerselva, was focused on. A land use plan including management principles were elaborated and some actions were taken. This work has altered Akerselva from a grey river to a salom river containing sweet water insects and bottom animals that are returning to the ecosystem. Today the second biggest river Alna is prioritized. Both Alna and Akerselva have been strongly influenced by industry and thus pollution. The industries have however moved out of the city or ceased to exist and the housing development has taken over as the main the pressure on the remaining green river banks. Also two other rivers, Ljanselva and Lysakerelva, are in good shape containing several fish species while two others are in a rather bad shape.

During the 90ties Oslo has experienced floodings especially in Akerselva. This has had both environmental and economic consequences since it is running through the most developed and urban part of the city and has illustrated for the management system how valuable green riverbanks are in order to handle the water load.



3. How are the ecological and environmental functions of greenstructure considered in landuse/landscape planning? How are the functions been managed to meet ecological and environmental goals?


Land use and landscape planning is carried out both according to formal and juridically binding planning instrumenst and according to more informal tools that have been elaborated in order to meet some of the ecological or "green" challenges. I will therefore describe them separatly in:


A. Formal planning instruments

B. Informal strategies


A.The formal instruments regarded as most important is the Master Plan, the Green Plan and the White Paper for Urban Ecology.

Master Plan:

The overall strategy of the municipality concerning the shortage of housing is densification of existing central residential areas in connection with the public transport network.Oslos Master Plan has during the last twenty years developed from a detailed land use plan to a more stategic plan. It points out areas suitable for densification, as for today being collective junctions, and gives point of directions of types of development. Although there is less greenstructure in central urban areas the existing green open spaces here are often prone to loss and fragmentation. The strategy is explained through four categories elaborated for densification planning purposes. These are:

  • areas suited for city expansion
  • areas with special considerations concerning landscape and vegetation
  • areas with protected buildings and squares
  • general densification areas

The last category includes the largest area and the freedom of the developers is extended compared to the first three categories



Ecological aspects from the White Paper for Environment is also included as background information for the Masterplan.

Green Plan:

This is a municipal plan for the greenstructure. Only parts of the greenstructure is juridically binding according to the plan. The rest is recommendations. It was adopted in 1993 and has since then been followed up the the Recreational Office. The plan is especially strong on defining missing links in the overall path/corridor system that links green areas togheter. Some areas have even been acquired though todays political strategies are looking for land and properties to sell rather than to buy.

White Paper for Urban Ecology:

This is the strategic plan for the environmental sector and has status as a white paper because it is adopted first in the city government and finally in the city parliament. It includes strategic guidance for the blue-greenstructure and biodiversity. It is revised every fourth year and the latest one will be adopted in the fall of 2002. It guides the different municipal agencies to what is prioritized politics the next four year periode and is also a signal to the public since it is published on internet.

Forest Management Plan:

The plan lines up priciples for the management of the urban forest sourrounding Oslo. The forest as a hole does not belong to the greenstructure, but the edge of about 1000meter is usually included in the greenstructure of the city. It was adopted in 1996 and is multifuctional with a main focus on recreational aspects. Also ecological considerations is regarded as more important than the economic aspects of timber.


B.Oslo has several more or less informal instruments in order to manage the green structure. The most important are:

  • Green Poster
  • District Recreation Map
  • Cities Environmental Report on Internet (CEROI) including European Sustainable Indicators
  • Environmental Certification of schools and kindergardens


Green Poster

Both the Green plan and the Master plan are meant for a higher level than the detail planning level. One of the results generated from research was a planning method for a so-called Green poster or Green chart. This is meant to be a professional tool serving as a "green warning signal" for planners and contractors. Based on several part studies of recreational, -landscape and biodiversity data the Green Poster is a synthesis and a strong recommendation highlighting the crucial green structure. The poster shows in other words which areas one should preserve and/or develop in order to take care of the different needs and functions connected to the green structure. It also identifies the need for recreation corridors and wildlife corridors. The results are presented on a single map designed as something like a poster which is to be placed in many relevant offices, therefore the name Green poster. During the long lasting Norwegian programme Environmentally Friendly Cities coordinated by the Minitry of Environment (1993-2000) the five participating cities developed the Green Poster and Oslo was the first to make on. Also several other cities have elaborated it, some as a point of departure for the legally binding Green Plan, others as a professional tool with no status other than serving as basic knowledge. In Oslo today the Poster is used by the Health and Nutrition Authorty as a fundament for evaluating detail plans. The reason for this is that according to the law this authority receives absolutly all detail plans. If they are in conflicts with the Green Poster, the plans are sent back to the Planning and Building Authority with remarks and for a new opinion. Today the Poster needs to be revised and information feeded into a data base system like the one used for biodiversity in order to get good statistics and a more professional design of the Poster.


District Recreation Maps.

Though being useful for an overall planning level the Green Poster turned out not too useful for a detailed planning level. The demand for even more detailed information became urgent. A pilot project was carried out together with one chosen City district. The focus was especially on how different groups of citizens used the green open spaces. An open space on a map does not show the physical qualities of the area and what kind of activities that it is suitable for. In this project it was therefore necessary to carry out fieldwork. Master students executed this with a geographer as a project leader and a reference group consisting of persons from different parts of the municipal management system following the project. The first map was finished in 1999 and so far 10 city districts have elaborated such maps. The maps are not only useful in detailed physical planning but also in connection with Local Agenda 21 processes. In Oslo the city districts play a major role in the work for Local Agenda 21. Each district has a LA21 coordinator. It is today 25 districts but the desicion to reduce the number of has been agreed upon in the city council.



4. How is ecology being implemented?



The strong pressure on urban and suburban areas in Oslo due to shortage of housing has introduced an urgent need for a tool ensuring that all decision-makers in physical planning have relevant biological information accessible at an early stage in the planning process. Also a political decision at the national level encourages all municipalities to survey and classify their biodiversity according to a scale of importance within 2003. The city of Oslo has just recorded the important habitats for biodiversity within the greenstructure in the build up area. The number of species in different groups recorded so far is shown in figure 2, 3 and 4. A small number of red listed plant species grow on wasteland, pavements etc. Except for these species the greenstructure is housing a major part of the biodiversity found in Oslo.


Tools to effectively apply biological information in daily physical planning cases are viewed as essential in order to preserve and manage natural habitats in highly pressured urban areas. A GIS based management tool for conservation and management of biodiversity and the process of implementation is therefore prioritized and elaborated. The main objective of this multi-agency effort is to ensure a sustainable and responsible management of the biodiversity within the municipality. The electronic tool elaborated makes it possible to combine biological information with any other information that is relevant for a planning issue. The system enables the local authority to early detect any conflicts between conservation interests and other types of land use as well as serving as an information system for the public and consultants dealing with environmental impact assessments. The management tool comprises the entire municipality including forested and agricultural land outside the urban and suburban area.

The Municipality has also bought an area from a private developer in order to save a pond housing "stor salmander". This was an ongoing discussion in the media and pupils close to the pond finally adopted the pond and thus got a lot of attention from the media. The conflict was unnecessary since the information was available but not known in the planning and building office. The new system will hopefully prevent such conflicts to happen in the future.



Since the City government has focused on the rivers of Oslo and thereby the green open areas along the rivers a committee was formed called "River forum" consisting of members from the relevant agencies in the municipality, relevant NGO's and relevant state agencies. Strategies and new routines for planning and management of the rivers and their adjacent open areas are being developed.


New developments and buildings

New developments that the municipality is responsible for demands an environmental plan concidering outdoor areas, flows and building materials. This is of importance for the local grenstructure and the small open spaces. The Public Housing Bank has also elaborated demands about out-door qualities and the bank rewards developments and private houses that take care of trees and other natural qualities on the property.



5. What is currently recorded about greenspace ecology?


One of the greatest challenges of greenspace ecology and other sustainable issues today is partly more data but most of all communicating the results and importance to the citizens. The tendency is that such issues drown in the information flow and the press will not convey environmental issues unless there are conflicts connected to them. That is one of the reasons for the participation in EEA`s project Cities Environmental report on Internet (CEROI). CEROI is an international methode that allows sustainable themes to be published on internet. Many european cities are working with the first edition. It is especially important in order to inform the public and start a dialog on the state of art and the different steps taken on sustainable issues. In Oslo,17 themes important for sustainability are described following the so called DPSIR methodology (D=driving forces, P=pressure, S=state, I=impacts, R=respons). Among these themes are greenstructure, biodiversity and water. The internet report also includes the 10 European Sustainable Indicators. One of these is access to green open spaces and is referred to earlier in this paper.

Norway has adopted a national Environmental Certification called the Environmental Lighthouse for small and medium size businesses and public offices. This is especially designed for businesses that will not undergo an EMAS or ISO 14001 certification. Demands are elaborated for each type of businesses. For instance schools and kindergarten have special demands that must be fulfilled before they get the certificate. One of the demands are to adopt a green open space and use this in the teaching. The city of Oslo has decided to adopte the Environmental Lighthouse. 14 kindergartens have achieved the certificate and the first group of schools are just about to start. We therefore expect an increased awareness of the role that these areas play in the greenstructure the coming years.

Working Group 1A - Comparison of Case Studies


Other papers relating to people/ ecology interface





Belgium - benefits for people

Sheffield to do




Ceské Budejovice

Comparison of case studies

UK - benefits of nature

Click button to return to:

updated Juky 2003