Universiteit Leiden

nl en

Counting lichens with your nose pressed to a tree

It may look a little weird: you spot a person pressing their nose to a tree, clipboard at the ready. That is our PhD student Tim Claerhout, who is carrying out fieldwork!

Tim Claerhout at the Garenmarkt in Leiden

As part of the HiddenBiodiversity research project, Tim studies which lichens and mosses grow in urban areas. Currently he is spending his days collecting data ‘in the field’, which means that he carefully investigates around twelve trees on a daily basis. Leiden, Rotterdam and Amsterdam are the cities where he conducts this research.

In order to be able to unambiguously record which lichens and mosses occur on a certain tree, Tim divides up the tree trunk: in every wind direction, five squares of 10 cm² are marked between 1 and 1.5 metres from the ground. And then it’s a matter of observing very carefully what tiny urban nature can be found there and the ratio between different species. It is important to do this very meticulously, says Tim, because a little less but very detailed data is more valuable than a lot of imprecise data.

In a few weeks – provided that the weather remains good enough – Tim will be done with the fieldwork. The next step is processing all that information: by combining and comparing the data he hopes to discover patterns. Which mosses and lichens occur where in the city, and does that have anything to do with the heat stress they experience? After all, it’s hotter in the city centre than in the suburbs. It has already been proved that lichens and mosses can disclose important information about air quality and pollution: maybe we can also use these species to reveal heat stress.

In the future of the HiddenBiodiversity project, Tim may also want to study urban nature hidden in other places, such as roofs and dead wood in city parks. The eventual goal of the research project is to be able to provide advise about urban biodiversity to, for example, municipalities.

Text: Emma Knapper

This website uses cookies.  More information.