Biodiversity – Green Roofs
Katsiaryna Kryzhanouskaya
November 2011
Topping off Biodiversity in cities
GO GREEN! Want to make your roof happy? Biologist Wolfgang Ansel from the German Roof Gardeners Union shares some tips and ideas.
Are green roofs just a fancy trend or a chance for urban wildlife to survive?
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A roof garden does not only look nice. It protects the building from fire, improves city’s climate and even works as a natural air conditioner. “It’s like a pullover for the house”, says Wolfgang Ansel, a 45-year-old biologist. He explains: In winter the green roof keeps the warmth, in summer – cools the building.
PHOTO: KRYZHANOUSKAYA
More nature, less care
More roofs than one may think:Trees are growing on the roof of an underground carpark in Dusseldorf
Like a real garden
German urban gardening went on top of houses in the 1970-s, Forster says. At that time it didn’t enjoy that much popularity. After the first excitement people realized that plants’ roots may well ruin the building or at least the roof. Since then the situation changed: modern technologies let house owners be sure that nothing threatens their property. Vice versa: such gardens help to prolong the roof ’s life up to 40 years instead of Calling for greenery: Forster surrounds himself with nature normal 15. Additional We stop in front of a one-stocomfort though is far from being ried brown building. It resembles the main reason for people. “When traditional Scandinavian houses: I ask customers why they want to the low slope roof is covered with have a green roof, they often mentall grass, slightly shaking under the tion environmental concerns. Somewind. He regrets the interview is times these people can’t even see taking place in autumn: “If you had their own roof – they need a ladcome here a couple of months beder to climb there”, explains August fore, it would have looked beautiForster. ful”. I disagree: the roof looks fanNowadays German roofs are tastic despite the season. considered “the greenest” in the
PHOTO: ANDREAS LISCHKA
• The first Nature Reserve on the top of the building was designed in Sheffield, England. The green roof repeats the
Extensive greening is the most widespread: Mosses, herbs and grass growing on such roofs do not need much investments and care. “It is enough to check once a year if everything is fine up there”, advises the expert. In Germany extensive greening composes 80 percent of the country’s “top” greenery. If you decide for this variant, what about planting lavender? These beautiful flower smells nicely and in case you need some relaxation, just add some home-grown plants into your tea.
world. Although specialists are not certain about the overall figure, they believe that the number grows up to 8 Million square meters a year - the area of around 1000 football pitches. This annual increase is mainly possible due to big investors. In Bonn, for instance, they are obliged to green flat roofs of all new buildings. One example of this policy is the T-Mobile office in the district of Beuel. All flat surfaces of this hightech construction are covered with high grass, pines and little ponds. The contribution of common people to the green roof movement is not that big yet. The 44-year-old biologist Dr. Gunter Mann, president of the Professional Green Roof Association, believes that people “green more and more“. Still the share of private roofs remains low: only around 1 percent. But even these little steps are important for preserving biodiversity in cities. Plants and small animals use roofs as their habitat, managing to live much higher than
they normally do. “If the layer of soil on the roof is thick enough, earthworms, for example, can live there for a long time. For earth animals, wild bees, spiders and others it is a really good alternative”, Dr. Mann says. According to the German laws, construction is seen as an intervention into nature, which should be compensated for. One of the ways of paying it off is roof gardening. “This is much more than just a trend and it does help the nature”, believes Dr. Mann. August Forster’s roof blooms every year since 1994, when he made it. After 17 years he still enjoys looking at it. “It blooms with white, pink, yellow and blue”, he says. Living in the industrial zone the green roof is the first thing the businessman sees through the window when he wakes up. “Sometimes there are squirrels hiding their nuts or birds catching insects. Well, if you love nature it doesn’t take long to decide for a green roof ”, Forster believes.
“This is much more than just a trend”
“Top”- facts international Green roofs as a source of creativity in the whole world local landscape with all its hills and valleys. Special feeders attract wildlife, and a weather station and webcam have been installed to provide research opportunities.
• Birds love green roofs as there they can always find food or even settle for nesting. Artists of Bonn noticed it and created for birds... the International Airport straight on the green roof of the National Art Hall. The winged pilots from the whole world are welcomed to stop here during their long flights. Among electric airport lights installed for them, birds can find food and nesting boxes. Welcome to Bonn! Art project for biodiversity: International Birds Airport
• The most famous green roof of the past was even included into the famous list of World’s Seven Wonders. The Hanging Gardens of Babylon built in 600 B.C. were nothing else as roof gardens of Babylon palaces. Scientists haven’t found any serious evidence yet to believe these gardens really existed. Well, even if it is only a legend it is an inspiring example for modern amateur roof gardeners.
• One of the biggest green roofs of Europe belongs to the University of Warsaw’s library. It is a real park with little ponds, trees and benches. While students study hard in the library, nature-lovers walk along
curvy paths, enjoying the panorama of the city. Special signs were installed there to remind people that this is a roof. Otherwise they would simply forget it!
• Thousands of years ago people greened roofs in Scandinavia. Romantic houses with real meadows and sometimes even goats grazing on the roofs became a tourist attraction. People take pictures of these houses admiring their unique appearance.Though aesthetical reasons were hardly important for ancient Vikings: the roofs were covered with moss and grass to make sure the house-dwellers will not freeze during the cold Northern winter.
Intensive greening turns roofs into real gardens where you can grow basically everything: from tomatoes to maples. “I have seen even roofs where people grow orchids“, says the biologist. Like a normal garden, the one on the roof requires a lot of attention. Money, money, money A personal roof garden somewhere in the downtown? Such a luxury should cost a fortune! “I can’t agree it’s expensive”, comments Wolfgang Ansel. “If we compare it to a new carpet or a parquet floor in the living-room, roof greening would be a way cheaper”. The expert believes, you can manage with 25-35 euro for a square meter. “And you don’t have to change it every ten years like a car“, he says.
PHOTO: DOMINIK STODULSKI
PHOTO: KRYZHANOUSKAYA
hile steel, concrete and glass conquer the cities, urban greenery becomes a “top” issue: with the help of tireless nature-lovers herbs, mosses, flowers and even trees migrate to roofs. I am walking in Buschdorf - an industrial part of Bonn: car dealers’ shops, storehouses, railway… Grass is replaced by asphalt, trees – by stainless-steel pillars. This is the place where you least expect to see greenery. And where you most want it. Soon I see a green island squeezed in-between concrete buildings: This is what I was looking for. August Forster, a businessman who lives and works here, invited me to show his green roof. In such surroundings it is clear that getting higher is a good solution for urban plants and animals. Roofs became a new habitat for numerous species, where they can live undisturbed by people. 54-year-old August Forster turns out to be a fit and tall grey-haired man. He heads a family company, established by his father in the 1950-s. I ask whether he had no other choice than to love nature – the family business is connected with gardening. He replies seriously: “I work here because it’s my calling”.
Add colors to biodiversity: Elegant ladybirds on your roof
So much buzz... Want to make your roof livelier? “Open there a hotel for insects”, suggests Wolfgang Ansel. This welcoming habitat is easy to make: Take some sticks of different kinds of wood, drill little holes in them and put into an open-ended wooden box. Add piles of dry twigs and leaves for ladybirds and get ready to welcome new guests.
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