Changes in macroinvertebrate richness and diversity following large scale rewetting measures in a heterogeneous bog landscape

摘要

Restoration measures in raised bog remnants frequently include the construction of dams, intended to retain rainwater and decrease fluctuations in the water table. However, comparative research in various bog remnants has provided strong indications that there are risks for macroinvertebrates. Risks include (i) rapid changes causing a disturbance, and (ii) similar changes at a large scale leading to a loss of heterogeneity, and consequently to a loss of species. This paper directly examines the risksassociated with rewetting measures in bog remnants by investigating and comparing the macroinvertebrate assemblages in the same area before and after measures took effect. At the scale of a single water body, species numbers mainly increased in water bodies that were not impacted by measures. Species numbers did not change in impacted water bodies. Moreover, the cumulative number of species declined in the rewetted parts, indicating that in general everywhere the same species benefited from the changes. This homogenisa-tion of the invertebrate assemblages was also evident at the scale of the entire reserve. On average, abundant species increased, while scarce species decreased. These results highlight the importance of heterogeneity. Especially minerotrophic conditions proved to be important. Therefore, restoration of the regional hydrology is of vital importance to the conservation and restoration of macroinvertebrate diversity.