Wetenschap - 11 september 2014

How green does your city feel?

tekst:
Roelof Kleis

Green space is a good thing. Especially in big cities, green space is
emerging as a kind of magic bullet. A salve for all urban ailments.
How green are our cities? And how do their residents feel about their green spaces? The Wageningen campaign Green in the City aims to find out, showcasing its own expertise in the process.

t’s a nice quiz question: What is the greenest city in the Netherlands? Residents of Heerlen or others with good memories will probably call out ‘Heerlen’. In an Alterra survey in 2009, the Limburg city of Heerlen came out on top. And it is still there, shows the latest update which was released last week. Within this urban area, there is 165 square metres of green space per residence. That is almost 30 square metres more than in Emmen, the second on the list, and 40 more than Lelystad, which came third. The ranking of the 31 largest towns in the Netherlands (unfortunately, Wageningen was not among them) provides good publicity for the Green in the City campaign which Wageningen UR is launching on the market. The campaign draws attention to Wageningen’s expertise in the area of urban green space.

Perceived green
So Heerlen is green. Twice as green as Amsterdam or Rotterdam, for instance. And as much as four times greener that Haarlem, which brings up the rear in the rankings. But the figures should be treated with a certain caution, as we learn from an explanation from Peter Visschedijk (Alterra, Governance). Alterra’s calculations only cover public green spaces that people can go into. Private gardens are not taken into account, and nor is street vegetation. Visschedijk: ‘Street vegetation is perceived green. That is different to a park in which you can walk, run or lie down. In terms of experience, street vegetation is actually like private vegetation.’

Visschedijk uses CBS data about land use for his ranking. Data about street vegetation are not included in it, and have only recently become available. Nowadays anyone wanting to see, literally, how green the Netherlands is, can look at Street View on Google Earth in the comfort of their own home. Another even nicer service is the website boomregister.nl, developed with input from Jan Clement of Alterra. The site has been online since the beginning of this year. ‘We know all the trees’, proclaims the website from its home page. Without a word of a lie. By linking aerial photos with infrared images, every tree in the country has been located and measured.

Wageningen vision
‘The title Greenest City is a relative concept,’ comments Visschedijk. ‘We are not particularly interested in the absolute numbers, but in trends and awareness-raising. It is not our aim to dish out medals. But the municipal councils certainly do look at these figures.’ The latest figures reveal some striking trends. On average, the cities have not got any greener since 2009. But there are big differences. Utrecht and Amersfoort, for instance, became 25 percent greener. Almelo, on the other hand, lost 30 percent of its green space.

The figures also show that half of our cities are not yet green enough. That is to say: they do not manage the 75 square metres per residence which is the guideline laid down in the government memo on spatial planning. But that norm refers to green space that people make use of. Urban vegetation nowadays encompasses much more than that. Vegetation makes people healthier, reduces air pollution, muffles noise pollution, contributes to water storage and cools cities down during heat waves. Vegetation literally makes a city more habitable. All these different functions of vegetation carry their own requirements and priorities.

For example, is the tree which is best for cooling the temperature also the best one for filtering particles out of the air? This raises the question of whether Wageningen has a broad and integral vision on vegetation. No, there is no such vision, says Annemieke Smit (Alterra, Nature and Society). ‘But there is an Alterra vision on urban green space: the Green Cities programme which started this year.’ In this programme, says Smit, the link is made between what green space means for the natural system and its effect on people. ‘What does it mean for people in a neighbourhood if there is more green space in the city?”

#GROENINDESTAD
A new feature of Green Cities is the formation of what are being dubbed dreamteams. These are groups of scientists who share broadly similar dreams when it comes to urban green space. Seven of these dreamteams are being formed around themes such as multifunctional space, urban metabolism, and environment and climate. Smit: ‘The aim is for us all to have a better idea of what the others are working on and combine the available knowledge. How can we think up new solutions together using the knowledge we have? Each team is going to look into what market exists and how we can tap into it.’ Combining functions is the key, says Smit. ‘You need to find smart combinations. Buffer vegetation along a stream to absorb flooding water is usable for recreational purposes as well. If you plant trees to absorb heat, perhaps you might as well plant fruit trees that you can harvest. That is the only way to make green space lucrative.’ This kind of idea soon gets scientists talking about ecosystem services.

You should always make the connection between the way the green space is experienced and its function

But Smit prefers to avoid that word when she is talking to members of the public and to entrepreneurs. ‘It is an academic term. And however great the concept might be, it distances you from people. It is too abstract. I have found a solution to that. I talk about harvestable vegetation, visible vegetation, and noticeable vegetation. That puts the emphasis on how it is experienced. Who is affected by this green space? Who is going to use it and who stands to gain from it? You should always make the connection between the way the green space is experienced and its function.’

The importance of how green space is experienced is prominent in the campaign as well, with residents of the cities in the study being asked to share their experience of urban green space on a Facebook group (How green is your city?) or on twitter (#groenindestad). So do Heerlen residents themselves see their city as especially green? And is Haarlem really the bleak and barren prospect the figures suggest? The collected images and comments should deliver a green book (or perhaps a black book) this autumn, which will be offered to town councils. 


Photo; Peter Visschedijk


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