Ground beetles as ‘early warning-indicators’ in restored salt marshes and dune slacks
Desender, K.; Maelfait, J.-P.; Baert, L. (2007). Ground beetles as ‘early warning-indicators’ in restored salt marshes and dune slacks, in: Isermann, M. et al. (Ed.) Restoration of coastal ecosystems. Coastline reports, 7: pp. 25-39
In: Isermann, M.; Kiehl, K. (Ed.) (2007). Restoration of coastal ecosystems. Coastline reports, 7. EUCC: Rostock. 67 pp.
Populations of ground beetles and spiders are continuously monitored since 1990 in the dunes and salt marshes of the river Ijzer estuary (Belgium), where a recent nature restoration project took place within the framework of LIFE. Immediately after restoration measures, continuous (year cycle) pitfall and window trapping was performed during several years in restored or newly developed salt marsh and dune slack habitats and compared to target ('old' salt marsh) habitats. In this paper, we focus on ground beetle assemblages and species quality from these samplings, based on some 40,000 beetles identified to 96 species. Results show several beetles new to the study area as well as a marked increase of several target species with high conservation interest (Red-list species). However, many of these species could be rapidly lost again unless natural dynamic processes are kept ongoing. Historical beetle data show that many species that disappeared from the area during the past century have not yet been able to recolonise. This is especially true for salt marsh species and possibly due to dispersal limitation. Many dune slack species re-appeared but did not establish viable populations. Moreover, several ground beetle species indicate increased sand instead of silt deposits in new and old salt marshes. Further invertebrate monitoring therefore is a prerequisite for a well-founded long-term evaluation of the executed nature development measures. Such monitoring will be of much interest, both for an evidence-based nature conservation management, for fundamental ecological research, but also as a possible early warning system for the need of additional management measures in the future.
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