Press release NIOO-KNAW

Citizen science results of Soil Animal Days 2018

30 October 2018

Woodlice back on top, slugs deterred by drought. The 4th edition of the Dutch Soil Animal Days saw 856 'citizen scientists' comb through more than 200 gardens and parks to find some 7500 soil creatures.

Findings that stand out after this year's long, dry summer: woodlice have regained their ubiquitous status, while slugs were spotted in fewer places. The drought may also explain why so many people had difficulties finding all the soil animals, although having a balanced garden does help.

After the wet early autumn of 2017 saw them slipping from our Soil Animal top three for the first time, woodlice returned to the top step of the podium this year. They were found in no fewer than 89% of gardens, followed by earthworms (85%) and arachnids (82%).

Effects of the drought: fewer slugs

The summer of 2018 was extremely hot and dry. According to Gerard Korthals, soil ecologist at NIOO-KNAW and Wageningen University and initiator of the Soil Animal Days, slugs are more vulnerable to drought and heat than other soil animals. 'This was borne out by the fact that the more than 800 citizen scientists who participated this year didn't see as many as them as before.'

Consequences in the longer term could be serious, says Korthals. 'After a number of years of this kind of extreme weather, the balance in the soil could change.' Slugs are important because they break down bits of dead organic matter, and are themselves a food source for hedgehogs and other animals.

Read more on the Netherlands Institute of Ecology website.

Netherlands Institute of Ecology

The Netherlands Institute of Ecology (NIOO) is one of the largest research institutes of the Royal Netherlands Academy of Arts and Sciences (KNAW), with more than 200 employees and students. It is specialised in fundamental and strategic ecological research. Since early 2011 the NIOO is based in a sustainably built research laboratory in Wageningen, the Netherlands.