Colonisation par la faune des dépressions créées par la verse des arbres suite à l'ouragan Lothar – premiers constats dans quelques forêts vaudoises | The role of depressions resulting from uprooted trees as new biotopes – preliminary observations in forests after hurricane Lothar

Abstract

On 26th December 1999, hurricane Lothar blew over Europe causing widespread damages, particularly on forested areas of Western Switzerland. One consequence of uprooted trees were depressions in the ground where rain water could collect and remain, depending on the soil characteristics. Colonisation of these aquatic depressions by plants and animals was surveyed in 2000. Our study showed that these new depressions were only colonized secondarily, organisms (insects and amphibians)preferring aquatic biotopes already present in the surrounding forest such as ditches, marshes or ponds. First colonization started around mid-May, but only within the depressions which were deep and filled with permanent water. The present study describes the colonization process of these depressions and discusses their contribution to forest biodiversity.