Ecological Groups of Coleoptera (insecta) As Indicators of Habitat Transformation on Drained and Rewetted Peatlands: A Baseline Study from A Carbon Supersite, Kaliningrad, Russia

Simple Summary On the modern climate agenda, drained peatlands are considered 'hotspots' that are responsible for a significant share of anthropogenic greenhouse gas emissions. The solution to this problem is usually associated with peatland rewetting, which aims to restore natural mire communities and their peat accumulation functions. The process of habitat recovery on both drained and rewetted peatlands requires the monitoring of biodiversity and ecosystem structures, with particular attention being paid to specific groups of organisms that may have an indicator value. Among these, some groups of beetles (Coleoptera)-as this order is the most species-rich on Earth-can be relatively indicative of specific environmental conditions, including different peatland habitats. Our studies provide baseline data on the beetle fauna of a drained peatland in the Kaliningrad region of Russia, designated for rewetting as part of the Carbon Measurement Supersite Programme. The recorded assemblage of 281 beetle species from 41 families differs significantly from the natural raised bog fauna. An analysis of the species composition enabled us to classify the beetle assemblage into specific groups according to their ecological relationships and peat bog biotope fidelity. Based on these results, we have identified the beetle indicator species for further monitoring the environmental changes during peatland rewetting.Abstract A total of 281 coleopteran species from 41 families were recorded from different sites of an abandoned cut-over peatland designated as the Carbon Measurement Supersite in Kaliningrad Oblast. This beetle assemblage is considered a baseline (pre-impact) faunal assemblage for further investigations during the 'before-after' (BA) or 'before-after control-impact' (BACI) study on a peatland that is planned to be rewetted. The spontaneously revegetated peatland has a less specialised beetle assemblage than at an intact raised bog. Tyrphobiontic species are completely absent from the peatland, while some tyrphophiles (5.3% of the total beetle fauna) are still found as remnants of the former raised bog communities. The predominant coenotic coleopteran group is tyrphoneutral generalists from various non-bog habitats (72.9%). The species composition is associated with the vegetation structure of the disturbed peatland (fragmentary Sphagnum cover, lack of open habitats, and widespread birch coppice or tree stand), which does not correspond to that of a typical European raised bog. The sampled coleopteran assemblage is divided into several relative ecological groups, whose composition and peculiarities are discussed separately. Possible responses to the rewetting measurements in different coleopteran groups are predicted and briefly discussed. A complex assemblage of stenotopic peatland-specialised tyrphophiles (15 spp.) and the most abundant tyrphoneutral generalists (31 spp.) were assigned as indicators for the environmental monitoring of peatland development.