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Week 19: Digital images preserve lichen researchers’ samples

The study of old plant samples has for decades, if not centuries, been a basic method for plant biology students. For example, at the otherwise sleek and modern Viikki Campus and the herbarium of the Department of Biological and Environmental Sciences, the dozens of decades-old plants glued to yellowed sheets of paper are still in much use by students.

Many of the carefully dried and pressed plants are well preserved, but lichen and moss samples are more difficult to keep. At worst, lichen samples can literally turn to dust if they are not handled extremely delicately.

Jouko Rikkinen, Professor of Plant Biology, who specialises in lichen, says that his students sometimes say that the only way to identify the smallest lichen samples under the plastic membranes is to look at the desiccated patterns of glue that reveal the shape of the sample that once was there. The digital enlargements of microscopic images do, however, enable the minute differences between species to be recognised.

In order to make displaying the images easier, the Department of Biological and Environmental Sciences has developed an e-learning project for the identification of plants and fungi, known as the Stack.  The online image library has proved from the outset to be an excellent research and learning tool. The problem in lichen research is that there is very little Finnish-language literature available, not to mention extensive image catalogues. There are some 800 moss and 1,500 lichen species in Finland. Currently, the Stack includes some images and detailed information on a little less than 50 lichen and moss species, but the aim is to gradually document all Finnish species.

A major element in the lichen researcher’s work is to make international comparison between samples. The international comparative study of samples collected when mapping out in less-known areas may take as many as 10–20 years, but the research cycles may speed up by years now that samples no longer need to be mailed around the world.

Lichen research is more significant than plant biology in general in contributing to the study of climate change. The samples collected at Kilpisjärvi Biological Station over a period of decades provide reliable information on climate change, and the comprehensive material allows for long-term analyses.

There are also plans to translate the material in Stack into English, so that it would be more accessible to the international academic community. In addition, the Stack includes sections that are directed at the general public. Why not make a head start on the summer and admire the high-quality images in the garden plants section!

Stack's online image library

Text: Mikko Arvinen
Picture: Jouko Rikkinen
www.helsinki.fi/digitalcommunications
Translation: Valtasana Oy

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