Green areas in cities are fundamental for people to live and thrive. By implementing green areas, the temperature in cities is lowered, the risk of flooding is minimized and noise decreased. Green areas do not only increase the well-being of humans, but also help increase biodiversity and provides several other beneficial ecosystem services.
Today’s cities can be compared with deserts concerning the biodiversity, due to the few green areas where species can live. Cities are also heat traps during heatwaves, which makes surviving difficult for many species. An increased amount of green areas help increase biodiversity and the chances of survival for species and give a positive impact on the urban climate.
One problem that cities face is that natural water cannot seep into the soil and be a part of the natural water cycle, due to the lack of green areas. Today, heavy rain and storms has become natural disasters that must be handled by transporting water in cities away through other infrastructure systems. Green areas can help reduce that problem, by functioning as ways where the water can run down.
Green roofs increase biodiversity in cities by offering green spaces, replaces the area lost when giving space for buildings and by mimicking the original habitat, supporting local biodiversity. By increasing the biodiversity, the area can serve more ecosystem services.
The BioDiverCity project
The City of Malmö started the project BiodiverCity in 2012 to develop products, services and processes to increase biodiversity in the city, with a vision of a greener, more attractive and healthier city. The project has tested a number of solutions of green roofs, green walls and facades, mobile vegetation systems and urban habitats.
In the BioDiverCity project, maintenance and cost of maintenance for houseowners was compared. By implementing green areas, property owners benefitted by the fact that the waterproofing of the roof increases by 25 – 50 years. In addition, green areas contribute to a less noisy environment. Less runoff of rainwater and help during heat in the summer months also lessens the burden on other infrastructure systems.
The concept green roofs include all vegetation installed on a roof. The green roof contributes to different benefits and ecosystem services depending on its composition. A sedum roof will give some services while a tree or a park will generate different services. An example from BioDiverCity is the development of biotope roofs, which has a thicker substrate then the normal green roof (sedum roofs) and will therefore serve more ecosystem services.
Examples from BioDiverCity
Some green roofs only need care a few times yearly, while other systems demand a more intensive maintenance. Green biotope roofs that were developed during the BiodiverCity project are:
1. Meadow habitat: Ystadvägen 56, Scandinavian green roof institute
2. Meadow habitat with perennials: Augustenborgstorget, Scandinavian green roof institute 3. Wetland: Kostergränd, Hauschild+Siegel
4. Seashore meadow habitat: Fregattgatan. MKB.
5. Seashore meadow habitat: Bomgatan 11, Skandia fastigheter
6. Sedum roof with varied substrate depth and high gradient: Skrivaregatan 1, Skanska
7. Ruderal habitats: Klippergatan, Byggvesta
8. Green roof in combination with solar panels: Quarter Sofia, MKB
9. Meadow habitat with woody plants: Ohboy, Lilla Varvsgatan 24, Hauschild + Siegel
Photo credits: Jonatan Malmberg/Scandinavian Green Roof Institute