The role of green in the city
Green (including water and soil) is important for the city as a living and working environment. It generates many ecosystem services, such as an environment for exercise, rest and relaxation (health, recreation), cooling, flood prevention and a certain degree of soundproofing. On top of this, green space of course contributes to the ecological structure and biodiversity and it can also be important from a cultural-historical perspective.
Green in the city is always under pressure from (increased) 'petrification' by buildings and infrastructure because space in the city is scarce.
Green infrastructure: valuable for the city
These days green infrastructure is talked about not only within the framework of nature policy but also in the urban context, in the form of parks, road verges, allotment complexes, cemeteries, ditches, canals, inland waterways and rivers (including the riverbanks). The task is to start viewing all those green elements as a single whole, to connect them where possible and create and/or preserve space for plants and animals.
How much urban green space do we have?
The Netherlands Environmental Assessment Agency [Planbureau voor de Leefomgeving] investigated, during the period 2000-2006, the development of the availability of green space within a 500 metre radius of the residential environment. The results show that, in some parts of the Netherlands, the amount of green space decreased during the period investigated, but increased elsewhere. The map does not provide any information over the type of green space and how it is used (the functionality) and does not include privately owned green space.
No norm exists for the quantity of public green space. The Spatial Planning Memorandum (2006) refers to a target figure: 75 m2 per dwelling. In 2003 the amount of public green space was less than this in 19 of the 31 largest municipalities and none of the four major cities achieved the target figure.
Identifying and valuing what we have
Local circumstances play a crucial role both when designing a new neighbourhood or when (re)designing green spaces in an existing neighbourhood. That is why it is important to carry out a proper assessment of the original situation: existing (landscape) elements, watercourses and riverbanks, old trees, road verges, corners of vegetation and public gardens, including the ecological quality. The analysis needs to cover the soil conditions, height differences, water management and – in the case of existing neighbourhood – the percentage of 'open soil': all types of (semi-)public green space, private green gardens, surface water, the presence of avenue trees, etc.
Ideally a city will have mapped out all its neighbourhoods on these points including the variation, and linked that data to data on flooding, nature in the city and the quality of the residential environment.
Use existing elements during design
A new neighbourhood may include parts of the old landscape. A neighbourhood gains character if old ditches are left in place (cultural history) and old trees are not felled. Special attention needs to be paid to areas of original soil (e.g. parks). Ecological riverbanks – which are excellent for biodiversity and water quality – do not always have to be created. In some cases proper management of existing riverbank vegetation can lead to a desirable riverbank which is rich in species.
Well thought-out design – green spaces have many functions
When creating urban green spaces it is a good idea to make maximum use of the various ecosystem services which can provide greenery. That makes investments more efficient. After all, this creates more value for people and nature and often enables costs savings.
Trees, vegetation, birds, bees, bats
Old trees in the city are scarce and most of them are younger than 40 years old. What
is more, certain fast-growing sorts (poplars, white willow) do not always live to be 40
(prone to being blown over). A lot of cities have developed policies to protect trees
due to their scarcity. Old trees make a significant contribution to the character of the
neighbourhood and are important for the quality of the living environment (cooling).
Public gardens and parks with structure (trees, bushes, herbs) and a varied
composition offer an excellent environment for animals of all shapes and sizes.
Varied herbal vegetation is important for insects that pollinate flowers, particularly
wild bees (including bumblebees), butterflies and hoverflies. Nature-friendly
riverbanks are excellent for water-based nature and water quality. A lot of birds nest in
Many of the popular trees and bushes have been introduced with some being
'indigenous', despite having originated from, for example, southern Europe. Real
Dutch trees and bushes are better 'adapted' to insects and other animals that live here.
If a neighbourhood provides a good habitat for birds, other animals and plants will
also benefit. The book entitled 'City birds: building, experiencing, protecting'
[Stadsvogels: bouwen, beleven, beschermen] by Netherlands Association for the
Protection of Birds [Vogelbescherming Nederland] details how design can help in the
context of four types of urban environment. In 'the stone city', 'the green city', the 'blue
city' and the 'new city' it is not that difficult to create a good habitat for a whole range
of species. In all cases this means the availability of food, shelter (security) and
Such information is available about bees and bats.
Together with residents
The Entente Florale Nederland refers to initiatives by residents as one of the five pillars of a vital, green city (in addition to recreation, health, economy and biodiversity, see www.vitalegroenestad.nl). The authorities cannot do it alone: without the actual involvement of residents in their neighbourhoods, all the lovely green plans will never become a reality or only through considerable effort, certainly now that many local authorities are having to cut costs. This applies to both new and existing neighbourhoods. Possible initiatives include a neighbourhood vegetable garden, a water playground, a urban farm, a maintenance team made up of people from the neighbourhood whose task is to take care of a public garden or park. If a green tradition is already established in a neighbourhood, this may also have an effect on whether the residents also practise green gardening.
Municipal green policy plan
Municipal green policy plans are, in principle, sectoral plans which provide a basis for longer periods of time for the management and maintenance of and investments in green (and blue) networks in the municipality.
Importance of green for other sectors
Policy in other areas also refers to social targets to which green infrastructure can contribute. Generally speaking the more the importance of green is acknowledged by other sectors, the stronger the green policy. We have identified three important fields of work:
Climate adaptation: as regards urban water management and heat, cities must adapt
to the increased frequency of heavy rain showers, heatwaves and long dry periods. As
regards the heavy rain showers, the focus has to be on water storage and the optimal
infiltration of rainwater (separate sewer). These two aspects are also important when
it comes to dealing with heat and/or drought, together with the green structure, such
as trees and bushes. In addition to this green roofs and façades can improve the living
environment. Rotterdam is a good example in the Netherlands of a city where a lot of
thought has gone into the green and blue infrastructure in relation to climate
Health and welfare: living and working in a green environment is beneficial for health
and welfare. This is something that is being worked on in many municipalities both at
home and abroad. In the Netherlands the 'TEEB city' report provides an overview based
on the (theoretical) case of '10% more green spaces in Bos and Lommer'. Groningen
and Zwijndrecht are examples of local authorities in which green and health are linked
(via urban agriculture/food and exercise and sport).
Integral urban development: 'green' is a constant feature of spatial plans or project
development. Often, no concrete information is provided on what kind of green is, or
should be, involved and qualitative aspects such as cultural history and biodiversity
continue to be underexposed. Within the framework of sustainable urban
development, green and water invariably play a key role because they are important
quality criteria and are important for climate adaptation and for health and welfare.
In the neighbourhood of Eva-Lanxmeer in Culemborg green structures have been used in an unusual way since 1999 for a variety of functions: water management, preservation of archaeological soil archive, extraction of geothermal heat, protection of drinking water sources and the prevention of heat stress. Due to all these different functions the design is inspired by the soil and reflects their different origins as a consequence of river flows. The design takes account of all aspects with the active bringing together of current and future residents playing an important role.
In the middle of the Haarlemmermeer area between Hoofddorp and Nieuw-Vennep, work is being carried out on a new 1000 hectare recreational green area named PARK21. The basis for the design is the existing landscape of waterways and ditches, fields and barnyards, with 'extended agriculture' being the main theme. A bathing lake is going to be created as well as sports facilities and, near the railway line and the A4 motorway, there are going to be attractions relating to Holland's (polder) history.
Design of green in the city:
- Characteristic city-and townscape features
- Geological values
- Indicative map of archeological values
- Development plans (double designation)
- Development plans (single designation)
- Conservation units for trees
- Source populations for trees and shrubs
Soil use in urban area:
- Carrying capacity - minimal foundation depth
- Locations with potential soil pollution
- Progress of soil investigations and restoration
- Robustness and recovering capacity of the soil
Regulative capacity by ecosystems:
- Potential availability of natural pollination
- Potential intake of particulate matter (PM10) by vegetation
- Potential natural pest control
- Waterstorage capacity of the subsoil
- Waterregulation of the subsoil
- Amenities of the landscape (recreation)
- Availability of playground areas
- Biomass - potential verge grass clippings