Within agricultural landscapes, isolated trees have been proposed as a means for augmenting arthropod species conservation outside of conventional reserve systems. This study examines ant community structure within isolated trees (Diphysa robinoides) and investigates the interaction of season with tree isolation in a tropical deciduous matorral in Veracruz, Mexico. Twelve trees in the matorral and 12 trees isolated within grassland were surveyed six times throughout the year by tree beating. Pitfall traps sampled the ant fauna of the ground beneath. This initial analysis compares a dry and wet season sample.
Despite tree deciduousness, arboreal ant abundance remained similar in both dry and wet season. Likewise, there was no significant shift to ground level foraging during the deciduous period. Arboreal and terrestrial species richness decreased significantly in the dry season. At ground level, species richness was highest in isolated trees, while numbers in pitfall traps were unaffected by landscape. No landscape–season interaction was found for any of the tested variables.
Indicator species analysis derived two arboreal ant species that were characteristic of isolated trees. These ant species both tend membracids, which have significantly larger colonies on isolated trees, suggesting that these indicator species are of some ecological consequence. Overall, more indicator species were found among the arboreal samples than those from the ground. Sampling in the wet or dry season produced similar numbers of indicator species.
Two-dimensional ordination of the ground and arboreal ant communities by Multidimensional Scaling demonstrated greater resilience in the ant community to climatic change than to tree isolation. These findings suggest a community that is resilient to climatic changes and in which tree isolation does not amplify seasonal impacts.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA