Fire – the influence of an extreme habitat disturbance on a threatened population of Desmoulin’s whorl snail: a case study from Poland

Abstract

Terrestrial gastropods are keenly sensitive to changes in vegetation structure owing to their dependence on moisture. For this reason, low survivorship and recolonisation are to be expected after a fire. The fire described in this paper probably started as a result of the deliberate spring burning of vegetation that got out of control. Analysis of the data collected immediately after the fire does not reveal significant differences in the numbers of snails between habitats. This suggests that there are no refugia for this population: no vegetation-related refugium was confirmed. After the fire, snail numbers were found to have crashed, but the slight increase during the season could have been an indication of incipient recovery. Because the population of this species was consistently small, no differences in survivorship between habitats, regardless of their type, were discernible. The effects of the fire on this population in the River Nida Inland Delta were devastating: while it did survive the fire, its numbers fell sharply, by as much as two orders of magnitude.