Ralf Verdonschot & Piet Verdonschot

herstelecologie, biodiversiteit, macrofauna, beekdallandschap

Habitattypen die in beekdalen voorkomen op het grensvlak van water en land, zoals kleine  zeggenmoerassen en elzenbroekbossen, herbergen onder ongestoorde omstandigheden een grote diversiteit aan ongewervelden. Vaak stellen deze karakteristieke semi-terrestrische soorten bijzondere eisen aan hun leefgebied. Dit artikel gaat in op deze randvoorwaarden, plaatst deze in het perspectief van de huidige beheerpraktijk en geeft aanbevelingen om het beheer voor deze ongewervelden te optimaliseren.

Stream valley invertebrate communities benefit from integrated stream and wetland restoration

Ralf Verdonschot & Piet Verdonschot

restoration ecology, biodiversity, macroinvertebrates, stream-valley-ecosystems

Stream-valley-habitats in the riparian zone of streams, such as fens with small sedge plant communities and alder forests host in an undisturbed state biodiverse invertebrate assemblages, with many semi-terrestrial invertebrates inhabiting the land-water transitional zone. Specific environmental conditions are required to establish and maintain populations of these species, which are in the light of the restoration and management of the systems, important to identify. Studies in stream valleys in the Netherlands, Belgium, Germany and Poland on carabid beetles, spiders, caddisflies and moths were used to identify the main drivers of biodiversity in these habitats from the scale of micro- to mesohabitat. On the microscale microtopography and an open vegetation structure were important factors determining the community
composition, whilst on the mesoscale the presence of scattered trees and shrubs as well as patches with open water were important factors. In contrast to reference stream valley fens restored sites in the Netherlands were species poor. This was related to a lack of small scale habitat variation at the sites, caused by a combination of intensive mowing and a high vegetation production due to eutrophication and hydrological disturbance. Furthermore, species establishment in restored sites might be hampered by a lack of source populations.