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Factors influencing the seed source and sink functions of a floodplain nature reserve in the Netherlands

Authors


  • Co-ordinating Editor: David Ward

  • Soomers, H. (corresponding author, H.Soomers@geo.uu.nl) & Wassen, M.J. (m.wassen@geo.uu.nl): Department of Environmental Sciences, Faculty of Geosciences, Utrecht University, P.O. Box 80115, NL-3508 TC Utrecht, The Netherlands
    Sarneel, J.M. (j.sarneel@nioo.knaw.nl): Ecology and Biodiversity, Faculty of Science, P.O. Box 80084, NL-3508 TB Utrecht, The Netherlands
    Patberg, W. (w.patberg@rug.nl): Laboratory of Plant Physiology, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands
    Verbeek, S.K. (s.verbeek@noorderzijlvest.nl): Water Board ‘Noorderzijlvest’, P.O. Box 18, NL-9700 AA Groningen, The Netherlands
    Verweij, P.A. (p.a.verweij@uu.nl): Group Science, Technology and Society, Faculty of Science, Utrecht University, P.O. box 80083 NL-3508 TB Utrecht, The Netherlands
    Van Diggelen, R. (ruurd.van.diggelen@ua.ac.be): Ecosystem Management Research Group, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium and Faculty of Spatial Sciences, University of Groningen. P.O. Box 800, NL-9700 AV Groningen, The Netherlands.

Abstract

Question: How do species traits and abiotic factors influence the extent of hydrochorous dispersal into and out of a small floodplain area along a free-flowing river in The Netherlands?

Location: The Kappersbult nature reserve (53°07′28″N, 6°37′14″E), which is a floodplain along the Dutch River Drentsche Aa.

Methods: Seeds transported by the river were collected in fine mesh nets for 24 consecutive hours once or twice a week for 1 year, upstream and downstream of the studied floodplain. Data on the captured seeds were related to species traits and abiotic factors and species composition in the floodplain.

Results: The floodplain functioned both as a seed source and sink. High levels of river water seemed to promote seed transport to or from the floodplain. Seeds of riverbank species occurred significantly more often in the river water than expected. Net source species had significantly higher seed production, taller stature and higher seed buoyancy, but lower site elevation than net sink species. Seed weight was significantly higher for sink species than for other species.

Conclusion: Our study found that inundation, and therefore more natural river water management, is a prerequisite for seed transport to and from a floodplain. The restoration of target floodplain vegetation may be successful for common species that produce many seeds and grow in proximity to the river. Consequently, it is expected that the probability of restoring vegetation types that occur further from the river, such as wet grasslands, by hydrochorous dispersal is low.

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