Initial Changes in Ground Beetle (Coleoptera: Carabidae) Species Assemblages Near Seasonal Ponds Surrounded by Forests Under Different Harvesting Practices

Seasonal ponds often form after spring snowmelt in forests of the Great Lakes region. Although such seasonal ponds are common, few US states set buffer-width guidelines to protect them when harvesting the adjacent upland forest. The objectives of this study were to determine if the carabid beetle assemblages near seasonal ponds differed from those in the adjacent upland forests prior to any logging, and then if these assemblages changed in response to various levels of tree harvesting within and adjacent to the 15-m-wide buffers that surrounded the seasonal ponds. The traps were placed within the buffers at about 7.6 m from the pond edge, and in the adjacent upland forest at about 46 m from the pond. The study was conducted in northern hardwood forests in Minnesota, using a replicated block design with four pond buffer treatments (uncut control in both the buffer and upland forest, or a clearcut upland forest with the buffer remaining uncut, partially harvested, or clearcut). The clearcut blocks varied from 6-26 ha in size. Carabids were collected with pitfall traps in 2000 (prior to winter logging in 2000–2001) and 2002 (1-year after logging). Overall, 15,857 carabid specimens were collected, representing 99 species. In 2000, before logging, 51 species were collected, including 15 riparian species. An NMDS ordination indicated high similarity between the species assemblages near and adjacent to the seasonal ponds. However, more riparian species were collected near ponds. In 2002, after logging, 92 species were collected, including 33 riparian species. Among the four buffer treatments, NMDS ordination indicated that the species assemblages in the clearcut buffers were the most distinct from the control buffers. In addition, although the clearcut buffers had the most species and the most riparian species, forest-associated carabids were present in all four buffer treatments. Although retaining forested buffers around seasonal ponds was not required to maintain high carabid diversity in the short-term following tree harvesting, such practices would ensure protection for the ponds themselves as well as associated flora and fauna.