Anthropogenic and environmental factors influencing the spatial distribution of earthworms in Finland

This study aimed to examine the anthropogenic and environmental factors known to be driving non-native earthworm distributions in post-glacial environments using secondary data that was collected in Finland. Two datasets were used and analyzed independently; U. Helsinki, collected in 2015 by university researchers in forested environments, and Matoseuranta, a citizen science initiative where data was collected primarily in 2017 by grade school students, from grades 3-9, and their teachers. For each dataset, a presence and abundance generalized linear model (GLM) was used to assess the extent to which the identified variables: temperature, precipitation, soil pH, population density, distance to the nearest road, land cover, and UTM northing drive earthworm distribution. Through the use of themed models, it was found that the GLM using only the variable northing best fit the U. Helsinki dataset for both presence and abundance. In contrast, the null model, the model with no predictor variables, fit the Matoseuranta data the best. It is likely that northing is acting as a proxy for environmental and anthropogenic variables that follow this south-north gradient such as temperature, road network, and population density. These results indicate different drivers of earthworm distribution in different environments with urban locations less sensitive to the variables constraining earthworm distributions in forests due to increased likelihood and frequency of an introduction event.