The effects of forest management on terrestrial habitats of a rare and a common newt species

Abstract

Many amphibian species spend part of their life cycle in terrestrial habitats. However, their exact requirements regarding terrestrial habitats have often remained enigmatic. We aimed to compare the terrestrial habitat use of a common (smooth newt) and a rare newt (great crested newt) species around their breeding ponds, to see whether habitat preferences are linked to the rarity of a species. We tested the effects of forest habitat characteristics on newt populations of seven ponds. The ponds were monitored with terrestrial drift fences at different distances and in different habitats surrounding seven ponds in southeastern Finland during 2 years. We fitted all models using a Poisson generalized linear mixed model. Both newt species distinctly favored forests with high understory vegetation cover. Captures were most numerous in the old forests directly adjacent to the ponds. Both the common species and the rare species showed similar habitat use, but there was an indication that the rare species avoided clear-cut areas and had more need for the shelter provided by canopy and field-layer vegetation, especially when the distance to pond increased. Based on our findings, the maintenance of sheltering vegetation around the ponds is very important, especially for the rare species. However, this requires the retention of both field-layer and canopy coverage, and specific management principles—such as avoiding clear-cuts—should be adopted to maintain favorable conditions.