Epsilon Archive for Student Projects

Abstract

Sand pits are a valuable habitat which can hold many sand living species including several endangered ones. As many sand habitats with exposed sand are declining, sand pits have a potential as a substitute habitat.

This study was conducted to see what effect the area of a sand pit has on species number and composition of ground beetles (Coleoptera: Carabidae). Also, the effects of other environmental variables were tested, for example the proportion open sand, vegetation cover, sun exposure and tree cover. The study was conducted in the county of Uppsala in 2008 and included 13 sand pits with areas between 200 and 180,000 m2. Pitfall traps were used as sampling method.

The study showed that the area of the sand pit affected the number of sand living species, which increased with an increasing area. The medium sized sand pits (~5,000 m2) had the highest number of sand living species, while the largest sites (~100,000 m2) had slightly less species probably because the large sites had a more homogeneous habitat. In smaller sand pits the proportion of sand living species was lower which indicate an edge effect.

The species composition was quite similar between most sites irrespective to its area. However, some of the small sand pits had a deviating composition due to the edge effect. Still, this suggest that a wide range of areas of the sand pits seems not important to preserve to include all sand living ground beetle species, even if some variation always is preferable. The species composition is however influenced by proportion open sand.

Based on this study, the recommendation is that sand pits preserved should have an area of more than 2,500 m2. A recommendation of an optimum area cannot be given as large sites with a heterogeneous habitat might be as species rich as medium sized ones. However, as smaller areas are more cost efficient to preserve the main focus is recommended to be on medium sized sand pits.