Exploring the impact of Formica exsecta ants on soil properties above the tree line in northern Sweden

Abstract: Ants are considered ecosystem engineers due to their effect on the soil properties and their ability to alter the flow of energy and nutrients. Many studies have focused on ants in boreal forests,but few have focused on the ant’s effect on the tundra. This study focuses on Formica exsecta mounds effect on soil properties above the tree line in the Abisko area. Soil moisture and soil temperature were measured in the field while organic matter content and gravimetric moisture content were measured in the lab. 113 soil samples from the summer of 2021 and 2022 were analysed. The samples were taken from inside the mound and from three distances from the mound. I found a significant difference both in nest moisture and nest temperature in the mound compared to the soil outside the mound.However, I found no significance for organic matter content at the different distances from the mound or for the gravimetric moisture content. Soil temperature and soil moisture is clearly impacted by the ant mounds, but it is not clear how far from the mound it affects the soil.