Netherlands-Wetlands: Proceedings of a Symposium held in Arnhem, The Netherlands, December 1989

326 Pages·1993·29.055 MB·English

by  W. J. Wolff (auth.), E. P. H. Best, J. P. Bakker (eds.)

Netherlands-Wetlands
Developments in Hydrobiology 88
Series editor
H. J. Dumont
Netherlands-Wetlands
Proceedings of a Symposium held in Arnhem, The Netherlands,
December 1989
Edited by
E.P.H. Best& J.P. Bakker
Reprinted from Hydrobiologia, vol. 265 (1993)
Springer Science+Business Media, B.V.
Library of Congress Cataloging-in-Publication Data
A CLP. Catalogue record for this book is available from the Library of Congress.
ISBN 978-94-010-4904-7 ISBN 978-94-011-2042-5 (eBook)
DOI 10.1007/978-94-011-2042-5
Printed on acid-free paper
All Rights Reserved
© 1993 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1993
Softcover reprint of the hardcover 1st edition 1993
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical
including photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner.
v
Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Vll
INTRODUCTION
Netherlands-Wetlands
by W. J. Wolff .................... ... .. ........ .. ............ ... ............ . .
CASE STUDIES
Coastal systems
Nutrient cycling and foodwebs in Dutch estuaries
by P. H. Nienhuis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
The Dutch Wadden Sea: a changed ecosystem
by V. N. de Jonge, K. Essink & R. Boddeke ....... .. .. ... ........ .. .......... .... 45
Salt marshes along the coast of The Netherlands
by J. P. Bakker, J. de Leeuw, K. S. Dijkema, P. C. Leendertse, H. H. T. Prins & J. Rozema 73
Large river systems
The rivers Rhine and Meuse in The Netherlands: present state and signs of ecological recovery
by W. Admiraal, G. van der Velde, H. Smit & W. G. Cazemier . . . . . . . . . . . . . . . . . . . . . . 97
Base-rich freshwater systems
An ecosystems approach to base-rich freshwater wetlands, with special reference to fenlands
by G. van Wirdum ...................... ........... ........................... 129
The structure and function of fen lakes in relation to water table management in The Netherlands
by H. de Haan, L. van Liere, Sj. P. Klapwijk & E. van Donk ... .................... 155
Wetlands of recent Dutch embankments
by W. Joenje & B. Verhoeven ........ ........... ... ........ .......... ..... ..... 179
Nutrient-poor freshwater systems
Nutrient-poor freshwater wetlands
by L. W. G. Higler .. ...... ......... ... .... ....... ........ .... .. .. .. ... ..... .. . 195
The Bourtanger Moor: endurance and vulnerability of a raised bog system
by W. A. Casparie ............................................................ 203
Hydrological differences between bogs and bog-relicts and consequences for bog restoration
by J. M. Schouwenaars .................. ..................... ...... ....... .. .. 217
Ecology and management of moorland pools: balancing acidification and eutrophication
by H. van Dam & R. F. M. Buskens .. ... ................... .. ....... ....... ... . 225
VI
Stream valleys as wetlands
by L. W. G. Higler & P. F. M. Verdonschot ....................................... 265
Wet dune slacks: decline and new opportunities
by H. W. J. van Dijk & A. P. Grootjans .......................................... 281
ECOLOGY, CONSERVATION, MANAGEMENT, RESEARCH AND POLICY
The ecology of The Netherlands wetlands: characteristics, threats, prospects and perspectives for
ecological research
by E. P. H. Best, J. T. A. Verhoeven & W. J. Wolff ................................ 305
Wetlands policy of the Dutch government: failure or success?
by F. Colijn, R. Uyterlinde & H. W. Kroes ....................................... 321
Hydrobiologia 265: vii, 1993.
E. P. H. Best & J. P. Bakker (eds), Netherlands-Wetlands. VB
Preface
The Netherlands is a country rich in water. The variety in water bodies is enormous taking the relatively
small size of the country into consideration. Most land is situated below sea level, and would be inundated
without the management measures required to keep it dry. Three large rivers, the rivers Rhine, Meuse
and Scheidt, cross the country and form extensive estuaries in the coastal areas. Former sea arms have
been closed partly or completely, with consequences for water quality and biotic communities. Because
the country is so rich in water bodies it also hosts many wetlands.
Scientific and public awareness has been growing during the last decade that the original wetland
character of The Netherlands is unique. Therefore, the Netherlands Ecological Society (,Oecologische
Kring') and the Netherlands Society for Aquatic Ecology ('Hydrobiologische Vereniging') jointly organ
ized a symposium on 'The Netherlands Wetland', December 1989, in Arnhem (The Netherlands).
The symposium was meant to (1) summarize the existing knowledge on structure and function of the
wetland types characteristic for The Netherlands, (2) identify gaps in knowledge, and (3) indicate new
avenues for ecological research.
This book is a compilation of most of the seminars presented during the symposium. The introduction
treats not only The Netherlands as wetland in a larger landscape but also the various wetland types within
the country itself. The subsequent case studies concern representative wetland types. Introduction and
case studies, both give an historical, hydrological, physico-chemical and biotic characterization of the
wetland concerned, give a description of management measures in the past and in the present, summarizes
the threats of the systems and indicate perspectives for the ecosystems given the present environmental
conditions and the expectations for short- and long-term changes therein. In the introduction special
attention is paid to the border-crossing biotic elements like birds. These sections are followed by a
summary of the ecology of the Netherlands wetlands and indications for future ecological research.
Finally, environmental policy and its consequences for management on a national, regional and local scale
is discussed.
Wageningen/Haren ELLY P. H. BEST
J. P. BAKKER
Hydrobiologia 265: 1-14, 1993.
E. P. H. Best & J. P. Bakker (eds). Netherlands-Wetlands. 1
© 1993 Kluwer Academic Publishers.
Netherlands-Wetlands
W.J. Wolff
DLO-Institute for Forestry and Nature Research, P.O. Box 46, 3956 ZR Leersum, The Netherlands and
Dept. of Nature Conservation, Agricultural University, Wageningen, The Netherlands
Key words: wetlands, The Netherlands, wetland history, wetland policy
Abstract
The Netherlands occupy 41,864 km2 of which about 6,600 km2 (16%) have been classified as interna
tionally important wetlands. About 3000 km2 (7%) have been included in the Ramsar Convention list
of internationally important wetlands.
The situation of the wetlands in The Netherlands has seen large changes during the last 2000 years.
Thousands ofkm2 of peatlands have disappeared; thousands ofkm2 of coastal salt marshes and a similar
area of shallow lakes have been reclaimed for agriculture.
The Dutch wetlands occupy a key position in the bird migration of the West-Palaearctic flyway.
The hydrology of The Netherlands and of Dutch wetlands is dominated by the river Rhine. Hence,
nutrients and contaminants imported by the Rhine and from other sources have a major impact on Dutch
wetlands. Reduction of pollution and eutrophication is a major requirement for conservation of Dutch
wetlands. Dutch politics appears to be moving in this direction.
Introduction mulated in Ramsar, Iran, in 1971. It entered into
force in 1975 when seven countries had acceded
Literally translated Nederland (,The N ether the treaty. The Netherlands ratified this conven
lands') means the Low Country. Hence, it is not tion in 1980 and it is in this period between 1971
astonishing that The Netherlands always have and 1980 that the word 'wetlands' became part of
been and still are a very wet country. This is il the Dutch language, especially the jargon spoken
lustrated by many topographical names, such as by conservationists and politicians.
'Waterland' (water land), 'Zeeland' (sea land), The Ramsar Convention aims at the conserva
and the many toponyms containing the terms tion and wise use of wetlands and of the popu
'-dam' or 'polder' (drained land). lations of waterbirds occurring in these wetlands.
However, although every type of wetland in Although in the early years the Convention put
The Netherlands can be named with a specific much emphasis on waterbirds, the Ramsar Con
Dutch word, there is no general term in the Dutch vention is essentially not a bird treaty, but a wet
language denoting wetlands. What is wetland lands treaty. Under this treaty the government of
elsewhere, is land to the Dutch. The word 'wet The Netherlands has prepared an official list of
land' was introduced into the Dutch language es wetlands of international importance (Rooth,
pecially because of the participation of The Neth 1985, 1989). Of this Dutch list enumerating 103
erlands in the so-called Ramsar Convention. This wetlands with a total area of 6,600 km2 10 wet
'Convention on Wetlands of International Impor lands with a total area of about 3,000 km2 have
tance especially as Waterfowl Habitat' was for- been designated for inclusion in the international
2
List of Wetlands of International Importance re should be considered to form part of these wet
ferred to in Article 2 of the Convention (as per 1 lands.
January 1990). This means that about 16% of Part of the Dutch wetlands qualify as such
the territory of The Netherlands is considered to under all definitions. However, about half of The
consist of internationally important wetlands and Netherlands consists of agricultural land lying
that about 7% of its territory actually has been below sea level. Originally this land used to be
registrated as an internationally important wet very wet, and hence wetland, but due to centuries
land. However, The Netherlands are wetter than of civil engineering (Van Veen, 1962) the water
that! table is now more or less fixed below the surface
of the soil. In clayey and sandy arable areas this
water table may occur down to 1-2 metres, but
Definitions of wetlands in peaty grassland areas the water table may be
only 10-20 cm below the surface. The latter type
In general terms, wetlands are areas where satu of agricultural areas still may be considered as
ration with water is the dominant factor deter wetlands, because of the high water table and the
mining the nature of soil development and the organisms occurring. Figure 1 shows the distri
types of plants and animals living in the soil or on bution of the different types of wetlands in The
its surface. Wetlands are transitional systems be Netherlands at present.
tween land and water where the water table is Some Dutch words denoting specific types of
usually at or near the surface or the land is cov wetlands have become incorporated in the inter
ered by shallow water. According to Cowardin national scientific literature. Such words are:
et al. (1979) wetlands have one or more of the
- wad (singular, plural: wadden) denoting unveg
following attributes: (1) at least periodically, the
etated tidal flats in the northern (Friesland,
bottom supports predominantly hydrophytes
Groningen) part of The Netherlands; the plu
(water plants); (2) the substrate is predominantly
ral form is well known in the international
undrained hydric soil and/or (3) the substrate is
scientific literature on coastal areas;
nons oil and is saturated with water or covered by
- slik denoting unvegetated (muddy) tidal flats in
shallow water at some time during the growing
the southern (Zeeland) part of The Nether
season of each year.
lands and the NW (Flanders) part of Belgium;
The 'Convention on Wetlands of International
due to Belgian scientific studies 'slikke' is now
Importance as Waterfowl Habitat' defines wet
widely used in the French scientific literature;
lands as 'areas of marsh, fen, peatland or water,
- schor meaning salt marsh in the southern part
whether natural or artificial, permanent or tem
of the country; again due to Belgian studies
porary, with water that is static or flowing, fresh,
'schorre' is often used in French scientific pub
brackish or salt, including areas of marine water
lications.
the depth of which at low tide does not exceed six
metres'. Another Dutch word which has acquired some
Several authors (e.g. Shaw & Fredine, 1956; status outside The Netherlands is polder, origi
Miller, 1976; Cowardin et al., 1979 and Frayer nating from the SW-Netherlands and NW
etal., 1983), however, set the lower limit of wet Belgium (Dekker, 1971) and originally denoting
lands at the extreme low water of spring tides or, an embanked and reclaimed salt marsh. Along
in non-tidal waters, at a depth of 2 or 3 metres, the Wadden Sea, especially in Germany and
because this is the maximum depth at which Denmark, the Frisian word koog has obtained the
emergent plants normally grow. same meaning; it is still used in Germany ('Koog')
According to the Ramsar Convention islands and Denmark ('kog'). Nowadays 'polder' in The
situated within wetlands and channels deeper Netherlands also denotes an area with an inde
than six meters situated within coastal wetlands pendent hydrology regulated by man.
3
12'/\1
dunes
_ salt marshes
D
saline lakes
_ freshwater lakes
[:::::;::;::;:::3 fen mires
o 50
km
Fig. 1. Present distribution of wetlands in The Netherlands.
Geological and historical development of The geological development may be summa
wetlands in The Netherlands rized as follows (Zagwijn, 1986). After the last Ice
Age sea level in the North Sea rose rapidly. When
Geology the rate of sea level rise declined at about 6000
B.P. a system of barrier beaches and islands de
Quaternary geology has prospered in The Neth veloped, situated approximately along the present
erlands during the last decades and has resulted western and northern coastlines. With a sufficient
in several palaeographic reconstructions of the supply of sediment the tidal basins behind the
topography of the country (e.g. Pons & Wiggers, barrier coast filled in until the tidal inlets could be
1959,1960; Pons & Van Oosten, 1974; Van Staal closed by wave action, especially in the areas with
duinen et al., 1979). Zagwijn (1986) summarizes smaller tidal amplitudes. In the former tidal ba
all available evidence in an interesting series of sins marsh vegetation developed which gradually
maps. Figures 2 and 3 are derived from his maps changed into ombrotrophic raised bogs. At larger
and show the distribution of wetlands in The tidal amplitudes and/or in areas with a shorter
Netherlands at about 100 A.D., i.e. during the supply of sediment, viz. the Wadden Sea area and
Roman occupation, and around 1200. the south-western part of The Netherlands, the