Evaluating the use of dominant microbial consumers (testate amoebae) as indicators of blanket peatland restoration

Peatlands represent globally-important ecosystems and carbon stores. However, large areas of peatland have been drained for agriculture, or peat has been harvested for use as fuel or in horticulture. Increasingly, these landscapes are being restored through ditchblocking and rewetting primarily to improve biodiversity and promote peat accumulation. To date we have little knowledge of how these interventions influence the microbial communities in peatlands. We compared the responses of dominant microbial consumers ( testate amoebae) to drainage ditchrestoration relative to unblocked ditchesin a UK upland blanketpeatland (Migneint, North Wales). Two techniques were used for restoration: (i) dammed ditcheswith re-profiling; and (ii) dammed ditcheswith pools of open water behind each dam. Testate communities in the inter- ditchareas changed markedly over time and between treatments illustrating the potential of this group of organisms as indicators of blanketpeatland restoration status. However, the responses of testate amoebaeto peat rewetting associated with restoration were partially obscured by inter-annual variability in weather conditions through the course of the experiment. Although there was considerable variability in the response of testate amoebaecommunities to peatland drain blocking, there were clearly more pronounced changes in samples from the dammed and reprofiled treatments including an increase in diversity, and the appearance of unambiguous wet- indicator speciesin relatively high abundances (including Amphitremastenostoma, Archerella flavum, Arcelladiscoides type, Difflugiabacillifera and Difflugiabacillarium). This reflects a shift towards overall wetter conditions across the site and the creation of new habitats. However, water-table was not a significant control on testate amoebaein this case, suggesting a poor relationship between water table and surface moisture in this sloping blanketpeatland. Our findings highlight the potential of testate amoebaeas bioindicatorsof peatland restoration success; however, there is a need for caution as mechanisms driving change in the microbial communities may be more complex than first assumed. Several factors need to be taken into account when implementing biomonitoringstudies in peatlands including: (i) the natural variability of the peatland ecosystem under changing weather conditions; (ii) any disturbance connected with the restoration procedures; and (iii) the timescales over which the ecosystem responds to the management intervention. Our results also suggest an indicator speciesapproach based on population dynamics may be more appropriate for biomonitoringpeatland restoration than examining changes at the community level.