Ask Oppla question by Josefina Enfedaque

In terms of public engagement, urban biodiversity could be a useful indicator, easy to understand by citizens, to measure the " environmental health of cities". How many species are in an average European city? ( small, medium size, big city) What is the typical distribution? How many species has a "healthy city"? Could you provide quantitative examples of cities where Nature-Based Solutions have increased urban or peri-urban biodiversity? What about alien species ? (Usually urban parks and gardens use exotic species) How to develop a simple biodiversity indicator to label cities, areas and interventions? ( easy to use by politicians to explain the impact of their actions to citizens, for example, number of autochthonous species) Many thanks


urroundings at least in most parts of Europe (this will be different for example in Manaus). This does not only account for invasive or exotic species but also for indigenous species and even red list species. The reason is the high niche diversity. The number of species is hard to answer. It depends on the type of species (are we talking about plants, insects, vertebrates,...) as well as on the climate. A reasonable measure would be the difference between the number species of a specific category compared to the number species of that category in the area around the city. The choice of the indicator depends on the question at hands: if we are concerned about conservation we should look at the richness or the diversity of red list species if it is about landscape aesthetics we should look for colorful flowers that attract wild pollinators.

A good start to dive deeper into the topic of urban species diversity with respect to plants would be:

Knapp, S., Kuhn, I., Schweiger, O., & Klotz, S. (2008). Challenging urban species diversity: contrasting phylogenetic patterns across plant functional groups in Germany. Ecology Letters, 11(10), 1054-64.

Kuhn, I., Brandl, R., & Klotz, S. (2004). The flora of German cities is naturally species rich. Environmental Research, 6, 749-764.

Posted on: 3 Mar 2016 - 14:25

Researchers are increasingly measuring urban biodiversity. You will find a good example here:

These researchers counted 77 bird species in Sheffield and have estimates of bird abundance. Much useful information on urban biodiversity was collected in the Biodiversa project URBES. The website is gone but the products can also be accessed here:

Take a look at Factsheet number 2. Finally a good source is the cities and biodiversity outlook: In general, these websites will tell you that there is quite some biodiversity in cities which is often overlooked. Recently for instance, research in UK showed that pollinator diversity is higher in cities than in adjacent intensively managed croplands. Cities should thus be part of the solutions to enhance biodiversity.

In the EU, many projects are thus addressing urban biodiversity. GreenSurge ( and GreenInUrbs (a COST action) are good examples of such research funded by the EU. Finally the MAES initiative on mapping and assessment of ecosystems and their services is running a pilot on urban ecosystems. The pilot will come up with suggestions and indicators on how to map and assess urban ecosystem condition. We specifically try to answer the question what is a 'healthy city'. The MAES report on urban ecosystems should be ready by the next Green Week in June when it will be presented. One of our case studies (Lisbon) includes alien species in their biodiversity assessment. They are seen as cultural species, not as pressures. The city of Lisbon uses the CBI index to measure urban biodiversity (city biodiversity index) for measuring progress to biodiversity targets set for the city. Finally, the work on nature-based solutions in cities is still at the start with calls being launched for concrete demonstration projects.

Posted on: 3 Mar 2016 - 15:25

European cities have big differences not only on size but on its internal structures. For example you can have a look to the LANDSAT images of Barcelona, Berlin, Roma and Stockholm. All at the same scale and from the same time of year. Barcelona has a quite high population density on its metropolitan area, four times the value of Berlin. The inner structure of Stockholm is also very different, with barely 1/3 of lakes, 1/3 of green and 1/3 of built.

But the density values are not necessarily a bad new:  on Mediterranean areas there is a need to aggregate people in order not to run out of land for other purposes (industrial activity, agriculture, natural areas).  

The sense of quality of life for people from Barcelona is much more dependent on the quality of its peri-urban landscapes.  The beaches and the Collserola mountain range already provide a good flow of ecosystem services to its citizens. 

So, it is not easy to make just a unique and common index for all cities throughout Europe.  The number of autochthonous species can become a proxy of the density or size of the city.

A first approach could be a comparison of urban structures at metropolitan scale. Maybe making comparisons of the rate of green/constructed surface with some weighting related to biodiversity, absolute quantity of people, and size of the metropolitan area. Total biomass could be a good index but not efficient on non-forested natural features like beaches and sea. 

The problem of exotic species is probably common to all Europe. Not only linked with ornamental plants and domestic fauna.   A fact much more linked to the processes that drive to what is known as novel ecosystems.  Probably the abundance of exotic species is a less efficient indicator of environmental quality than the presence of exotic invasive species. 

Nature-based Solutions are a great instrument to foster flows of ecosystem services. Probably more efficient as the metropolitan areas become more dense.  And at this point, urban planning is the most relevant tool, by managing the relationship between dense urban habitats and high quality green areas; and what is most important, shortening the distance between dwellings and work places to avoid consumption of fossil combustible and loss of time.

Posted on: 3 Mar 2016 - 16:25

There is also lots of work going on in TURAS ( looking at how urban biodiversity conservation can be promoted through multifunctional green infrastructure design:

Some examples:

Molineux, C., Gange, A.C., Connop, S.P. and Newport, D.J. (2015) Using recycled aggregates in green roof substrates for plant diversity. Ecological Engineering. Volume 82, September 2015, Pages 596-604.

Nash, C., Clough, J., Gedge, D., Newport, D., Ciupala, M.A and Connop, S. (2015) Initial insights on the biodiversity potential of biosolar roofs: A London Olympic Park green roof case study. Israel Journal of Ecology & Evolution: Green Roof Special Edition.

Bastock, J., Whitfield, P, Clough, J. and Connop, S. (2014) SUDS Guidance: London Borough of Tower Hamlets. Available at:

Connop, S. Lindsay, R., Freeman, J, Clough, J., Kadas, G. and Nash, C. (2014) TURAS multidisciplinary urban landscape design guidance: Design, incorporation and monitoring of Barking Riverside brownfield landscaping. University of East London, London, UK.

Connop, S., Nash, C., Gedge, D. Kadas, G, Owczarek, K and Newport, D. (2013) TURAS green roof design guidelines: Maximising ecosystem service provision through regional design for biodiversity. TURAS FP7 Milestone document for DG Research & Innovation.

I hope some of it is useful.

Posted on: 9 Mar 2016 - 12:26