Ant Diversity and Community Composition in Alpine Tree Line Ecotones
Department of Botany & Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
Institute for Alpine Environment, Eurac Research, Viale Druso 1, 39100 Bolzano, Italy
Department of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
Author to whom correspondence should be addressed.
Academic Editors: Roberto Pizzolotto and Mauro Gobbi
Received: 18 September 2020 / Revised: 9 February 2021 / Accepted: 27 February 2021 / Published: 4 March 2021
Alpine grasslands are among the few terrestrial habitats not obviously dominated by ants. Yet few studies have addressed how ant communities change along tree-line ecotones on mountains. We combined five survey methods to assess ant assemblages along the tree line at five mountains in the south-central Alps of Italy. Ant species richness peaked directly at the tree line, but this was not due to a mixing of forest with grassland species. In subalpine forest and at the tree line, ant assemblages were dominated by mound-building red wood ants. Community composition and functional species traits indicated competition as a potential effect of community assembly in subalpine forest. Further, habitat features such as elevation, dwarf shrub cover, and the extent of a soil humus layer shaped species composition of ant communities around the tree line.