Effects of peat mining intensity on green frog (Rana clamitans) occurrence in bog ponds

Abstract

We assessed whether peat mining intensity influences the use of bog ponds by green frogs (Rana clamitans). We selected 21 ponds in three areas undergoing different levels of peat mining: 1) mined (vegetation completely removed exposing bare peat, prsence of drainage ditches with little or no water), 2) in preparation to be mined (vegetation intact but presence of drainage ditches filled with water), and 3) natural (vegetation intact, absence of drainage ditches). We estimated green frog abundance and reproduction using a combination of sampling techniques. Green frogs were detected more often at ponds in the moderately disturbed section than at ponds in either the mined bog or natural sections. Furthermore, no green frogs called at ponds on mined surfaces, as opposed to ponds on either natural or moderately disturbed surfaces. Tadpoles occurred only in the moderately disturbed section. This suggests that ponds on mined surfaces provide suboptimal habitat for green frogs. Within the moderately disturbed section, drainage ditches may provide additional breeding habitat and facilitate movements between ponds. However, if this positive effect occurs, it is only temporary because moderately disturbed sections are inevitably mined. Although preserving vegetated corridors or buffer zones around bog ponds within mined surfaces may not necessarily increase pond use by amphibians in the short term, it will facilitate the restoration phase of mined sites by providing a source of dispersers of bog plants and wildlife, including amphibians.