Life strategies of ants in unpredictable floodplain habitats of alpine rivers (Hymenoptera: Formicidae)

authored by

Armin Lude, Michael Reich, Harald Plachter

Abstract

Increasingly, stochastic catastrophes are considered to be essential for the survival of certain species and the development of ecosystems. Floodplains of pristine, braided rivers in the Alps (Central Europe) are examples for ecosystems shaped by stochastic floods and well suitable as a model to study the effects of 'unpredictable' changes of the environment to species. The ant communities of 2 distinct ecological groups in 3 adjacent stretches of the Upper Isar (Germany) was analysed. Most ant species are not adapted to occasional flooding and so were absent from sites frequently inundated. At least 9 species were able to survive floods. Only Formica selysi Bondroit 1918 regularly colonises relatively young, unvegetated gravel islands and bars. There, this species attained densities higher than any other ant species in the study area (up to 30 nests per 100 m²). The response of Formica selysi to flooding was tested in the field and in lab experiments. On open gravel bars 72% of the colonies survived floods in their nests. Swimming rafts were formed when the nest entrance was mechanically impacted or if animals were not able to find shelter in the nest. Swimming rafts consisted of several dozen workers, a queen and brood. Field observations demonstrated, that rafts can successfully reach the river banks again. Peak floods are necessary to provide suitable habitats for some ant species of pristine floodplains which do not survive in more densely vegetated habitats.

External Organisation(s)

Philipps-Universität Marburg

Type

Article

Journal

Entomologia generalis

Volume

24

Pages

75-91

No. of pages

17

ISSN

0171-8177

Publication date

16.09.1999

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Insect Science

Electronic version(s)

https://doi.org/10.1127/entom.gen/24/1999/75 (Access: Closed)