Indirect effect of the invasive exotic fungus Ophiostoma novo-ulmi (Dutch elm disease) on ants

Abstract

Biotic invasions have become major agents of human-driven global change. One of the most virulent species for trees is the Dutch elm disease (DED) (Ophiostoma novo-ulmi). However, few are the studies that investigate its indirect impact on the fauna. In a well-preserved area of Sierra Morena (Cordoba, Spain), we report the repercussion of tree cover loss due to DED on ants (Hymenoptera, Formicidae), a bioindicator group. For 10 years, before and after DED, we studied ant assemblages in different zones with a gradient of invasion. In the most affected ones, indicator species of well-preserved habitats decreased, while generalist and opportunist species increased. The forest management practices undertaken after the disease had an even more devastating effect, and thus the logging and removal of dead trees in the Bejarano stream caused that its ant assemblage became more similar to the one of a nearby meadow than to the ones of close riparian areas.