Text by Lauri Laanisto
It probably happens quite rarely, but sometimes some of the most fundamental theoretical questions can be studied using applied research approach. Studying urban ecosystems is one of these rare occasions. In a blog post from last year I wrote about the theoretical advances of studying vegetation in cities: “…one of the smartest ways how to build infrastructure representing “future climate” conditions would be to work in a city environment. Couple of degrees warmer than the surrounding areas, more chemistry in the air, different soil conditions, almost no natural buffer zones left – this is the future of our landscapes …”
Now, a group of researhers from around Europe (latitudinal range from southern Spain to Estonia) have written a review paper describing the climate mitigation potential of the most common urban tree species in different parts of Europe. So, in addition to just offering shade – which can be beneficial in so many ways and not just by providing protection against excess light (we recently had a review paper about shade) – trees also protect against dusty winds, remove pollution from air, provide habitat for animals providing ecosystem services, emit useful organic volatiles, etc.
This review paper tries to provide a holistic evaluation of woody plant traits that are associated with all these usefult services trees provide in cities, focussing especially on air pollution mitigation.
On a sidenote – our lab is associated with an urban diversity and habitat fragmentation ERA-NET project starting in February, once again together with colleagues from all over Europe. In the course of this project we will try, in addition to applied part of the study, to find some answers to more theoretical questions of how functional and phylogenetic diversity of bacteria, plants, lichens, insects and vertebrates (in differently sized and populated urban ares) is affected by habitat fragmentation, air pollution and warmed climate, which is typical to cities. So there probably will be more blog post about urban ecosystem functioning.
Citation: Grote, R., Samson, R., Alonso, R., Amorim, J. H., Cariñanos, P., Churkina, G.,… Niinemets, Ü. … & Paoletti, E. (2016). Functional traits of urban trees: air pollution mitigation potential. Frontiers in Ecology and the Environment, 14: 543-550. (link to full text)
In an increasingly urbanized world, air pollution mitigation is considered one of most important issues in city planning. Urban trees help to improve air quality by facilitating widespread deposition of various gases and particles through the provision of large surface areas as well as through their influence on microclimate and air turbulence. However, many of these trees produce wind-dispersed pollen (a known allergen) and emit a range of gaseous substances that take part in photochemical reactions – all of which can negatively affect air quality. The degree to which these air-quality impacts are manifested depends on species-specific tree properties: that is, their “traits”. We summarize and discuss the current knowledge on how such traits affect urban air pollution. We also present aggregated traits of some of the most common tree species in Europe, which can be used as a decision-support tool for city planning and for improving urban air-quality models.