Fens and Bogs in the Netherlands: Vegetation, History, Nutrient Dynamics and Conservation

490 Pages·1992·25.88 MB·English

by  J. T. A. Verhoeven (auth.), Jos T. A. Verhoeven (eds.)

Fens and Bogs in the Netherlands
Geobotany 18
Series Editor
M.J.A. WERGER
The titles published in this series are listed at the end of this volume.
Fens and Bogs in the Netherlands
Vegetation, History, Nutrient Dynamics and Conservation
edited by
J. T. A. VERHOEVEN
Springer-Science+Business Media, B.V.
Library of Congress Cataloging-in-Publication Data
Fens and bogs in the Netherlands : vegetation. history. nutrient
dynamics. and conservat ion / edited by J.T.A. Verhoeven.
p. cm. -- (Geobotany : 18)
Includes index.
ISBN 978-90-481-4099-2 ISBN 978-94-015-7997-1 (eBook)
DOI 10.1007/978-94-015-7997-1
1. Peat bogs--Netherlands. 1. Series.
GB628.54.F46 1992
553.2' 1'09492--dc20 91-31097
Printed on acid-free paper
AII Rights Reserved
© 1992 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1992
Softcover reprint ofthe hardcover Ist edition 1992
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
permis sion from the copyright owner.
Table of Contents
Preface vii
I. Introduction 1
by J.T.A. Verhoeven
II. Holocene peat formation in the lower parts of the Netherlands 7
by L.J. Pons
III. Climatological, stratigraphic and palaeo - ecological aspects of mire development 81
by W.A. Casparie and J.G. Streefkerk
IV. Draining-digging-dredging; the creation of a new landscape in the peat areas of the low
countries 131
by G.J. Borger
V. Plant communities and synecology of bogs and heath pools in the Netherlands 173
by J.J. Barkman
VI. Types of terrestrializing fen vegetation in the Netherlands 237
by A.J. Den Held, M. Schmitz and G. van Wirdum
VII. Terrestrializing fen vegetation in former turbaries in the Netherlands 323
by G. Van Wirdum, A.J. Den Held and M. Schmitz
VIII. Carr vegetation: plant communities and succession of the dominant tree species 361
by J. Wiegers
IX. Nutrient dynamics in mires of various trophic status: nutrient inputs and outputs and the
internal nutrient cycle 397
by W. Koerselman and J.T.A. Verhoeven
X. Conservation and management of bog and fen reserves in the Netherlands 433
by J.G. Vermeer and J.H.J. Joosten
List of contributors 479
Index 481
v
Preface
Peatlands are fascinating ecosystems. They are Boudewijn Beltman, Jon den Held, Harm Piek,
inhabited by a wealth of especially adapted plant Drs. Niek van Heijst, Drs. Hermien van Sloch-
species, such as peat mosses, insectivorous teren and Dr. Taeke Stol, who participated in
plants, and nitrogen-fixing shrubs. They also the early stages of the process. The help of Drs.
have a 'memory' often going back thousands of G.J. Baayens in the correction of chapter 5 is
years, recorded in the layers of plant remains gratefully acknowledged.
accumulated underneath the present plant cover. Chapters 6 and 7 have been supported by the
Many peatlands are relatively low-productive foundation 'Oecologia Trajectina', Utrecht, by
and species-rich, and show vegetational gradients supplying grants made available by the 'Prins
related to water chemistry. Bernhard Fonds', Amsterdam and the 'Beij-
Peatlands have long been recognized for many erinck-Popping Fonds', Amsterdam. I am indeb-
values. The most conspicuous values appreciated ted to Marjolein Smithuizen and Dick Smit of
for the Dutch mires were probably the great the Illustration division of the faculty of Biology,
potential of the large nutrient stores in peat soils University of Utrecht, for the large number of
for agricultural purposes, and the high calorific drawings they produced for the book. Gerrie
value of peat when used as a fuel. These values Bransen helped with the printing of the final
have led to large-scale exploitation and destruc- versions of the various chapters.
tion of the once-extensive Dutch peatlands. done during my stay at the Smithsonian En-
Although the Dutch people are well-known vironmental Research Center (SERe) at
worldwide because of their history of large-scale Edgewater, Maryland, USA, supported by a
reclamations of peatlands, information on the grant from the Netherlands Organization for the
vegetation of the remnants of the Dutch peat Advancement of Science (NWO) and a Smithso-
mires, on their ecology, geologic history, func- nian Senior Postdoctoral Fellowship. I thank Dr.
tioning and conservation is largely lacking or Dennis Whigham of SERe for providing excel-
rather scattered in the international literature. lent facilities and for his moral support. He also
This, and my personal fascination with peat- critically read and improved chapter 1. Further, I
lands, has spurred me to compile a volume on am indebted to Dr. Marion Cambridge for cor-
various aspects of the Dutch peat mires. recting the English for most of the chapters and
I thank all the authors who have contributed to Prof. Dr. Marinus Werger, Editor of the
to this book, for their enthusiasm which carried Geobotany series, for his continuous interest in
them eventually through the long process of the progress of the book.
conceptualization, writing, discussing, rewriting
and more of the above to the final version of
their various chapters. I thank also Dr. Ir. Utrecht, February 1992 los T.A. Verhoeven
vii
CHAPTER I
Introduction
J.T.A. VERHOEVEN
... silvis horridus aut paludibus foetidus ...
.. . horrendous because of its forests and foetid because of its wetlands ...
1.1. Scope 1.3. Terminology
1.2. Specific characteristics of Dutch mires 1.4. References
1.1. Scope made use of peat for salt preparation, fuel pro-
duction and growing crops. In the 18th and 19th
These first written qualifications of the Dutch centuries, large-scale bog and fen excavations
landscape by the Roman author Tacitus reveal brought companies and small farmers consider-
something of the vast wetland wilderness that able profits.
abounded at his time in the area now known as Mires in the present Dutch landscape are
The Netherlands. The floodplains of medium remnant bogs that exist as high mounds in a
and large-sized rivers, the coastal marshes and totally excavated matrix of mineral agricultural
the bogs on the lands more remote from the soils, and fens that have developed in ponds
rivers and the sea together formed a large-scale created by peat dredging. Mire conservation is-
mosaic of forested and herbaceous wetlands. sues continue to stir public opinion in major land
This pristine landscape, hardly accessible to use planning decisions in the Netherlands.
man, has been converted through the centuries This volume focuses on the geology, land use
into a totally reclaimed countryside with careful- history, palaeoecology, ecology and conservation
ly controlled water levels and very intensive of peatlands (fens and bogs) in The Netherlands.
agriculture. Small remnants of natural wetlands My objective in organizing the volume was to
and wetlands artificially created over the cen- provide detailed accounts that together give a
turies are still a very conspicuous component of representative picture of the studies that have
the Dutch landscape. Many of these wetlands are been carried out in the Dutch mires over the past
managed by nature conservation agencies and 25 years. Although some of the material has
contain a diverse flora and fauna with many been previously published, most of it appeared
increasingly rare species. in Dutch publications that are only locally avail-
Mires (peat-forming ecosystems) once covered able or almost completely unknown beyond
a major part of the land surface but most of Holland.
them have been lost as a result of reclamation Geomorphologically, the area covered in this
and drainage, peat cutting and peat dredging. volume can be subdivided into two parts in
Peatlands were long considered dangerous but which mire formation has been essentially differ-
beginning in the 11th century man increasingly ent. The western part consists of the coastal
1. T. A. Verhoeven (ed.), Fens and Bogs in the Netherlands: Vegetation, History, Nutrient Dynamics and Conservation, 1-6.
© 1992 Kluwer Academic Publishers.
2
plain and the floodplains of the large rivers 1.2. Specific characteristics of Dutch mires
(Rijn, Maas and Schelde). Mineral soils in these
flat areas were mostly deposited during the In order to understand the characteristic features
holocene. The eastern part is primarily pleis- of Dutch mires, it is necessary to distinguish
tocene in origin and consists of extensive, locally between two sets of factors that have influenced
rolling aeolian sand deposits. Mire formation peat formation, mire structure and mire dis-
in both areas started in the late pleistocene. tribution. The first set of factors is the geomor-
Extensive 'plateau' -type raised bogs developed phological setting of the Dutch coastal plain, the
on the eastern sands and in similar adjacent interaction between marine and fluviatile flood-
areas in northwestern Germany. Mires in the ing events and the climate during the holocene.
western coastal plain and along the rivers The second set of factors is associated with
developed under strong influence of river and human impacts that resulted in draining, cultiva-
sea flooding. tion, dredging and cutting since about the 11th
Chapters 2, 3 and 4 of this volume deal with century.
the geologic and land use history of Dutch mires. The decrease in the rate of sea level rise at the
Chapter 2 (Pons 1992) is a comprehensive geo- end of the pleistocene resulted in the develop-
graphic and pedological account of peat forma- ment of large freshwater areas behind a series of
tion in space and time in the western coastal coastal sand barriers located roughly along the
plain. Chapter 3 (Casparie & Streefkerk 1992) is present Dutch coastline. Mire vegetation de-
a detailed description of the various stages of veloped in the resulting shallow freshwater
development from fen to bog of the Bourtanger lagoonal basins, leading to a widespread system
Moor, a mire area in the northeastern, 'pleis- of fens and marshes. Many areas were fed by
tocenic' part of The Netherlands. Chapter 4 groundwater discharge from aquifers connected
details the history of peat draining, digging and to the sandy hills in the eastern part of the
dredging in The Netherlands and Flanders country (Pons 1992, Casparie & Streefkerk
(Borger 1992). 1992). Similar developments took place in val-
Chapters 5 through 10 provide detailed ac- leys within these sandy areas themselves.
counts of the present-day mire vegetation, The continued decrease in sea level rise and
synecology and management. Chapter 5 (Bark- favourable climatic conditions during the
man 1992) deals with bog remnants in the east- holocene resulted in rapid expansion of mire
ern Netherlands and northwestern Germany. areas, which eventually culminated in the forma-
This chapter also includes data on oligotrophic tion of raised bogs with perched water tables.
heath pools which have a vegetation that is Raised bogs especially developed on top of the
similar to that found in bogs. Chapters on vege- sands in the eastern Netherlands. Most of the
tation, synecology and nutrient dynamics of fens raised bogs were reclaimed beginning in the late
(Den Held et al. 1992, Van Wirdum et al. 1992 Middle Ages. In the coastal floodplains, domed
and Koerselman & Verhoeven 1992) and carrs complexes developed, with central bog areas sur-
(Wiegers 1992) focus mainly on terrestrializing rounded by vast areas of fens. Here, the situa-
fens that are so characteristic of the western tion was more dynamic than on the eastern
Netherlands where they presently occur in turf sands, as the fens were often eroded or de-
ponds created by peat dredging in former cen- stroyed by riverine and marine flooding. The
turies. Valley fens that locally occur in the flood- flooding events often covered the mires with
plains of brooks in the eastern Netherlands (e.g. clayey sediments. These coastal-plain mire sys-
Drenthse Aa, Grootjans 1986) are not covered. tems were much less common in Europe than the
Chapter 10 concludes the volume with a treat- raised bogs in the eastern part which also
ment of problems with mire conservation and occurred commonly further north and east in
management (Vermeer & Joosten 1992). Germany, Denmark and Poland.
3
Although more influenced by river floods and Only the discovery of widely dispersed bog peats
marine tides and storms, (for details see chapter with typical Sphagnum species by Polak (1929)
2, Pons 1992), peat formation in The Nether- demonstrated that bogs must have been im-
lands occurred in a way similar to that described portant on the coastal plain.
for other major peatlands (e.g. Moore & Bel- Peatland reclamation in the coastal plain re-
lamy 1974, Gore 1983). In general, freshwater sulted in the typical Dutch landscape of long,
depressions are colonized by macrophytes and narrow strips of land separated by drainage
eventually become dominated by large ditches. Dredging of peat below the water table
helophytes. These stages are known as primary for use as fuel in the 17th-19th centuries created
mires or rich fens. As soon as peat formation many long, narrow, rectangular ponds (Dutch:
raises the fen surface above the regional water 'petgaten') that are typically bounded by baulks
table, the fen becomes less nutrient-rich and (Dutch: 'legakkers') or drainage ditches. These
more dominated by mesotraphentous species. ponds became recolonized by aquatic plants and
These developmental stages are known as sec- helophytes that later developed floating mats
ondary mires or poor fens. If the mire is of (Dutch: 'kraggen') and ultimately turned into
sufficient size and if the climate is wet, peat herbaceous fens or forested carrs.
growth will continue to raise the mire surface. It must be stressed that conditions in the
As mires become increasingly dependent on rain dredged ponds would have been very different
water, they become less nutrient-rich and domi- from those in natural, wet depressions in which
nated by bog species such as Sphagnum spp. and peat can accumulate. First, water levels were
dwarf shrubs (tertiary mires or bogs). almost always stable in the ponds because of
The set of factors associated with the severe polder water management. This is an exceptional
human impacts are described in chapter 4 situation in wetlands as water table fluctuations
(Borger 1992). The impacts have resulted in are normally very characteristic and one of the
almost complete modification of the original major forcing functions of natural wetlands (Van
mires and in creation of new mires with charac- der Valk 1981). Second, the shape of the
teristics that are different from those of dredged ponds (narrow and long) was favourable
(semi)natural mires elsewhere in the world. For- for a rapid expansion of floating mats that de-
mer agricultural practices, such as clear-cutting, veloped inward from the baulks because of rela-
mowing, moss collection and grazing, are often tive protection from wind and wave damage.
now continued as nature management and con- Third, fen species will have been abundant in the
tribute to the 'non-natural' character of many ponds even just after excavation and the expan-
mires in The Netherlands. Nevertheless, most sion of remnant vegetation along the ditches will
mire reserves are characterized by high botanical also have favoured rapid recolonization.
diversity and contain many of the species that The controlled hydrology of Dutch fens has
also occur in natural mires. also meant that water chemistry has played a
Mires on the coastal plain have been most more important role in the development of fens
severely impacted by drainage and subsequent in these dredged ponds compared to the de-
reclamation for agriculture. The construction of velopment of natural fens. Depending on the
polders with a more or less regulated water table location of 'petgaten' in the landscape, fens may
has resulted in considerable subsidence due to receive rain water, surface water and/or ground-
peat shrinkage and oxidation (Schothorst 1982). water. 'Kragge' fens located in groundwater dis-
The characteristic pattern of mire complexes charge areas have small-scale gradients in water
with bogs surrounded by fens had disappeared chemistry because of the local existence of rain
by the Middle Ages. In fact, it has long been water lenses on top of the groundwater layer.
thought that the original mires in the western These gradients influence the vegetation and are
Netherlands had almost exclusively been fens. one of the causes of the high botanical diver-
4
Table 1. Glossary of Dutch words used in the various chapters
baggerbeugel long-handled tool for peat dredging
baggeren dredging
baggerturf peat extracted by dredging
boezem surface water reservoir
bolster topmost layer of rough bog peat
bonkaarde topmost layer of rough bog peat
bosveen wood peat
bovenveen-cultuur agricultural use of drained bogs
dekzand aeolian 'cover' sand
dijk dike
drijftil thin floating mat giving little support
eerd- organic top soil
gewelfd hoogveen raised bog
gliede disperse humus
Hollandveen Holland peat (see chapter 2)
hoogheemraadschap regional waterauthority
hoogveen 1. raised bog, 2. bog peat
horst hummock in carr forest
kragge floating mat
kwelder saltmarsh
kwelderwal saltmarsh ridge
laagveen 1. fenland, 2. fen peat
leem fluviatile 'loam'
legakker baulk (non-dredged strip)
meerstal bog pool
petgat long, narrow pond created by peat dredging
plas mere, broad
polder diked area with controlled water table
rietveen reed peat
schor saltmarsh
selnering salt making
slagturven dredging of peat
slik mudflat
spalterveen Sphagnum cuspidatum peat
stuifzand bare, sands actively moving due to wind action
terp constructed dwelling-mound
toemaakdek top soil created by mixing with 'bolster'
trekgat long, narrow pond created by peat dredging
turf (dry fuel) peat
veen 1. mire, 2. peat
veen op grotere diepte basement (deep) peat (see chapter 2)
veenkolk bog pool
veenkolonie peat- colony (see chapter 4)
veenmosveen Sphagnum peat
veenpolder peatland polder
veenweiden drained peatlands used for grazing
veraarding mouldering (see chapter 2)
verlanding terrestrialization
wad tidal flat
wetering canal
wijk ditch in drained peatland
witveen laminate Sphagnum cuspidatum peat
-wold toponymic suffix indicating wood peat
-woud ibid.
zeggeveen sedge (Carex) peat
zodde quaking fen