Impacts of restoration and management of raised bogs on biodiversity
Intact raised bog systems are not present anymore in The Netherlands and most of the West-European raised bog landscapes are destroyed or changed dramatically due to peat cutting, dehydration and nutrient enrichment. To restore raised bogs for the last 30 years measures are taken to restore raised bogs. These measures are mainly focussed on restoration of hydrological conditions suitable for Sphagnum recovery (rewetting by damming). These measures do not always result in restoration of raised bog vegetation. To provide more knowledge on the processes involved in successful restoration a research program was launched, financed by the Dutch ministry of Agriculture, Nature management and Fisheries. In this research program hydrology, as well as biogeochemistry and fauna of raised bogs is studied. Relatively little attention has been paid to the faunistic aspects of peatland restoration. Key factors in the composition and abundance of fauna communities characteristic of intact raised bog systems, including natural transitions to the surrounding landscape, were unknown.
The project is carried out by a consortium of the universities of Wageningen and Nijmegen, studying quantitative and qualitative hydrology and vegetation, and Bargerveen Foundation, studying the faunistic aspects of bog restoration. Project leader of Bargerveen Foundation is drs. Hans Esselink. The Departments of Environmental Studies and Animal ecology participate in this research project. Dr. Rob S.E.W. Leuven and prof. dr. Gerard van der Velde are co-promotor and prof. dr. Piet Nienhuis is promotor.
Restoration of degraded raised bog remnants: do aquatic invertebrates tell a different story?
To study whether restoration measures result in restoration of fauna communities characteristic of intact raised bog landscapes we started by studying aquatic macroinvertebrates, as restoration measures are mainly focussed on hydrology and waterquality. We compared aquatic macroinvertebrate assemblages within and between a variety of water bodies in intact raised bog systems in Estonia and Ireland and raised bog remnants under restoration in the Netherlands.
Bodies of water created by rewetting measures are inhabited by a number of characteristic raised bog species and rare species. However, in relict sites, which have not been effected by restoration management, these numbers are higher. Restoration of characteristic raised bog vegetations does not necessarily result in restoration of characteristic fauna, whereas several water bodies which have no valuable vegetation are inhabited by relatively high numbers of characteristic and (very) rare fauna species. A considerable number of these species are only found in remnant sites and have not been sampled in the restoration sites, even not in the sites of more than twenty years old or the sites with the most successful restoration of vegetation. Therefore, when restoration measures are being planned, it is important to take care of present populations, especially of rare and characteristic species. These populations can be the sources for colonisation of rewetted sites. In order to deal carefully with the fauna diversity in areas to be restored it is necessary to assess previously which species are present.
Another reason for the absence of a number of characteristic species can be the lack of specific water qualities and vegetation structures required to complete their life cycles. These habitat conditions are absent because part of the heterogeneity in abiotic and biotic conditions and transitions to more minerotrophic parts of the bog system is still not restored in remnants in the Netherlands. To avoid decline of the faunistic diversity of bog systems it is essential to safeguard populations of characteristic raised bog species still present in bog remnants and to try to restore (part of) the habitat variation of complete raised bog systems.
More details can be found in our publications.
In the research project on fauna, restoration and management of raised bogs (and also in other projects of Bargerveen Foundation) good opportunities for student research projects are available. For more information you can read examples (in Dutch) or contact me.