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The Walenboscomplex; a conservation site of national importance in Brabant, Belgium
THE WALENBOSCOMPLEX; NATIONAL IMPORTANCE
A CONSERVATION SITE OF IN BRABANT, BELGIUM
W. TIPS
Gemeentestraat 47, B-3200 KesseI-Lo, Belgium
ABSTRACT
The Walenboscomplex is one of the Jew remaining natural sites of the Hageland, a mainly agricultural region in central Belgium. The vegetation characteristic of the area requires periodic" management, protection on its own not being sujficient. A review oJthe legislation available to protect natural areas in Belgium is given. Because of damage by hunting activities, the threat of industrial development and water abstraction, together with the need Jbr conservation management, the Walenboscomplex can only be saved by its establishment as a nature reserve by government decree.
INTRODUCTION
The Walenboscomplex is one of the few remaining extensive 'natural areas' of the socalled Hageland. The Hageland, which means literally 'land full ol~ hedges', comprises an area between the cities of Diest, Aarschot, Louvain and Tienen (Vliebergh, 1921). It is situated east of Brussels, approximately in the centre of Belgium (Fig. 1). The rivers Dijle, Demer and Gete in former times protected the region from outside influences from the west, north and east. Only in the south was there no natural boundary. About 1780, when a map for the Austrian-Netherlands was drawn by Graf Ferraris, the region consisted of many small woods and marshlands with some reclaimed areas in between. Reclamation and drainage for agricultural and residential zones resulted in the almost complete disappearance of the typical landscape, in less than 150 years. Today little is left and even this is seriously threatened by industrial exploitation. Protection is needed now in order to save the still existing natural richness and to guarantee a worthwhile inheritance for future generations. 243 Biol. Conserv. (11) (1977)--@ Applied Science Publishers Ltd, England, 1977 Printed in Great Britain
244
Fig. 1.
w. TIPS
Map of Belgium indicating position of the Walenboscomplex (WBC) (B: Brussels. L: Louvain, T: Tienen, D: Diest and A: Aarschot). SITUATION AND GEOLOGY
The complex is situated near the centre of the Hageland and covers about 700 ha in the territory of the municipalities of Houwaart, Tielt and Sint-Joris-Winge. The greater part of these 700 ha is private property, but some smaller areas are owned by the semi-public 'Nationale Landmaatschappij'. The wood covers the Roeselberg, the Alsberg and the valley between this hilly region and the Brede Motte river (Fig. 2). In the north-east corner the boundary is formed by a brook, the Leigracht. The sources of the Brede Motte and a side-brook of the Molen-brook are in the marshlands situated in the valley. In the south-west corner the park of the castle of Kleerbeek links the complex to the valley of the Molenbrook, thus forming an integrated unique landscape covering about 10 km 2. The upper geological structure is Diestiaan (Pliocene), which consists of greeny coarse sands, with a cover of pleistocene, light, sand-loamy substrates. The soils in the wood are mixed and mostly very wet. In some areas a layer of peat is present and some peat-cutting in about 1930 has resulted in a number of fen-pits.
245
A CONSERVATION SITE OF N A T I O N A L I M P O R T A N C E IN BELGIUM
HOUWAART
install.
TIELT
Roeselberg
ST-
JORIS-WINGE 1 km
Heathland
Fen-pits - -
Fig. 2.
Boundary ~Roads
Map showing the main characteristics of the area.
MAIN BOTANICAl. CHARACTERISTICS
The most important botanical associations are of several different types, because the area includes both the hilly ground inthe south and the valley of the Brede Motte to the north. This results in numerous transition zones mainly from dry to wet biotopes. Most of these are oligotrophic and very poor in nutrients, Molinia caerulea Moench frequently appearing as an indicator of this condition. Natural succession tends towards an overall deciduous forest type, which together with open marshlands formed the landscape in former times. The last few remaining sites of
246
w. XlPS
heathland and the most valuable and scarce bluegrass meadow (Cirsio-Molinietum) in the valley are presently being overgrown by shrubs and trees. Little can now be done to save the bluegrass meadow and stop the succession to associations of Salicion cinereae because this stage is already too far advanced. Due to this process a number of butterflies (see below) have disappeared. The heathland sites which are also reduced to a very small area contain cross-leaved heath (Erica tetralix L.), heather (Calluna vulgaris (L.)), needle furze (Genista anglica L.) and broom (Sarothamnus scoparius (L.)) and can be classified as a Genisto pilosaeCallunetum. It is also in urgent need of careful management (see Fig. 3).
Fig. 3.
Heathland site at the Walenboscomplex in need of management.
A wet type of alder carr (Carici elongatae-Alnetum) is now the most characteristic vegetation type (Fig. 4). In those areas where the succession has reached the final stages or nearly so, there are forests of the Quercion robori-petraeae, mostly the association Querco-Betuletum molinietosum (oak-birch forest). Recent human influence has been responsible for much of these wet grounds changing to dry pine-forests with low biological diversity. In addition Canadian poplar (Populus x canadensis Moench) has been planted in some areas.
A CONSERVATION SITE OF N A T I O N A L IMPORTANCE IN BELGIUM
Fig. 4.
247
A l d e r c a r t at the Walenbos.
MAIN FAUNAL CHARACTERISTICS
Roelants (1975) lists a large number of birds including water rail (Rallus aquaticus L.), woodcock (Scolopax rusticola L.) and honey buzzard (Pernis apirorus L.) from the Walenbos. My own observations include long-eared owl (Asio otus (L.)) and buzzard (Buteo buteo (L.)). Apart from this general knowledge of the birdlife, little information is available on the fauna of the area. Among the best known are several uncommon butterflies. However, with the disappearance of the hay lands most of these species are no longer seen. In the collection of P. Halflants (Lubbeek) we found (Tips & Halflants, in press): white admiral (Limenitis camilla (L.)) (still present), marsh fritillary (Euphydryas aurinia (Rottemburg)), Glanville fritillary (Melitaea cinxia (L.)), spotted fritillary (Melitaea diamina (Lang)), heath fritiUary (Mellicta athalia (Rottemburg)), small pearl-bordered fritillary (Clossiana selene (Denis & Schiffermtiller)), pearl-bordered fritillary (Clossiana euphrosyne (L.)) and dark green fritillary (Mesoacidalia aglaja (L.)).
248
w. TIPS
Further biological investigations are being carried out by amateur biologists and the author.
THREATS TO THE AREA
Because its range of biotopes is of interest only to naturalists and biologists the Walenbos has been saved up to now from invasion by day trippers and from the effects of cultural eutrophication. However, as it is relatively unknown to the public the regional organisation Nature and Landscape VZW (Boutersem) has had to publicise the threats to the area, in order to arouse support from public opinion. Apart from the lack of management, there are two main threats to the future of the area. In the first place hunting activities each year result in a large area being cut out to create shooting positions. In the long term this will cause a general degradation and the destruction of valuable plant communities. Secondly there is the replacement of deciduous woodland by exotic species, mostly Corsican pine (Pinus nigra laricio (Poi.) Palibrin) and also the Canadian poplar. This type of change will be most unfavourable for the conservation of insects and birds characteristic of the Walenbos. Finally there is a possibility that the Walenbos will be used as a source of water for the region. There is already one minor pumping installation in the south-west corner and more intense pumping will, beyond doubt, be harmful to the wetter biotopes, such as the associations of alder carr (Alnion glutinosae), which are of national importance in Belgium.
LEGISLATION TO SAFEGUARD CONSERVATION AREAS
In Belgium there are several different ways of protecting valuable natural sites. In practice most of these procedures are inefficient due partly to lack of supervision and partly to the fact that responsibility is divided among different departments. Since 1962, the Ministry of Public Works has planned several 'green zones' in the 'Sectorial Development Plans'. The complex of the Walenbos is designated in the Sectorial Development Plan for Aarschot-Diest as both a "green zone' area and as a future nature reserve. The official statement accompanying the plan names it as a most important natural area. But although the legal procedure implies ratification by Ministerial Decree, followed by Royal Decree in 1977, full protection against agricultural and forestry activities is not guaranteed. Another protection method is "classification' as a Monument or Landscape by Royal Decree of the Ministry of National Education and Culture, which may be
A CONSERVATION SITE OF N A T I O N A L IMPORTANCE IN BELGIUM
249
applied to both private and publicly owned areas. Although the management of natural sites as reserves is possible by this procedure in practice this has never been realised by the government. Almost 300ha of the Walenboscomplex have been classified and another 300 to 400 ha will follow this year. During a period of nine months (the provisional classification time) preceding the decree, in which the integrity of the area is legally guaranteed, a number of serious violations have been recorded. In spite of the prohibition on all hunting activities, a battue has taken place. Again an area has been cut out to provide for shooting positions. Moreover serious damage was caused to the heathland remnant, by using part of it as a feeding-ground for pheasants. The ~Law on the Conservation of Nature' (12 July 1973) not only makes it possible to protect and manage natural areas as reserves but also interesting sites and landscapes for nature conservation purposes. In addition it provides for the management and supervision of the nature reserves by government personnel. Finally it is highly regrettable that there is no Nature Conservation Institute in Belgium up to the present time. According to the Law on the Conservation of Nature such an institute should have been founded two years ago. But the Ministry of Agriculture still refuses to take action under this section of the Law. Consequently field biology and research for conservation purposes in Belgium has to rely mainly on amateur biologists and private initiative.
THE FUTURE
It is obvious that the only effective way of conserving the Walenboscomplex is to make it an official nature reserve. Because several biotopes require management, for example the heathland site and all types of shrub biotopes such as the Carici elongatae-Alnetum, the present classification is not adequate. The designation of this area as an official nature reserve, as proposed in the Sectorial Development Plan for Aarschot-Diest, should be fulfilled as soon as possible, according to the Law on the Conservation of Nature. Although several hundred owners are involved in the proposed expropriation, this problem should not provide an excuse for failing to conserve an area as valuable as the Walenboscomplex.
ACKNOWLEDGEMENTS
I wish to thank Mr Pierre Halflants for his enthusiastic co-operation and Prof Dr S. G. Kiriakoff, Dr E. Kuyken, Mr A. Abts and Prof Dr H. Gysels for their help in several ways.
250
W. TIPS REFERENCES
ROELANTS,A. (1975). Het Hageland-Geologie-Bodem-Planten-groei-Vogels. Nu o[ Nooit, 5, 3-27. TIPs, W. & HALFLANTS,P. (in press). La collection entomologique de Pierre Halflants, notaire honorain/t Lubbeek (Gellenberg). I. Nymphalidae (Lep.). Linneana Belgica. VLIEBERGH, E. (1921). Her Hageland. Louvain, Davidsfonds,
A CONSERVATION SITE OF IN BRABANT, BELGIUM
W. TIPS
Gemeentestraat 47, B-3200 KesseI-Lo, Belgium
ABSTRACT
The Walenboscomplex is one of the Jew remaining natural sites of the Hageland, a mainly agricultural region in central Belgium. The vegetation characteristic of the area requires periodic" management, protection on its own not being sujficient. A review oJthe legislation available to protect natural areas in Belgium is given. Because of damage by hunting activities, the threat of industrial development and water abstraction, together with the need Jbr conservation management, the Walenboscomplex can only be saved by its establishment as a nature reserve by government decree.
INTRODUCTION
The Walenboscomplex is one of the few remaining extensive 'natural areas' of the socalled Hageland. The Hageland, which means literally 'land full ol~ hedges', comprises an area between the cities of Diest, Aarschot, Louvain and Tienen (Vliebergh, 1921). It is situated east of Brussels, approximately in the centre of Belgium (Fig. 1). The rivers Dijle, Demer and Gete in former times protected the region from outside influences from the west, north and east. Only in the south was there no natural boundary. About 1780, when a map for the Austrian-Netherlands was drawn by Graf Ferraris, the region consisted of many small woods and marshlands with some reclaimed areas in between. Reclamation and drainage for agricultural and residential zones resulted in the almost complete disappearance of the typical landscape, in less than 150 years. Today little is left and even this is seriously threatened by industrial exploitation. Protection is needed now in order to save the still existing natural richness and to guarantee a worthwhile inheritance for future generations. 243 Biol. Conserv. (11) (1977)--@ Applied Science Publishers Ltd, England, 1977 Printed in Great Britain
244
Fig. 1.
w. TIPS
Map of Belgium indicating position of the Walenboscomplex (WBC) (B: Brussels. L: Louvain, T: Tienen, D: Diest and A: Aarschot). SITUATION AND GEOLOGY
The complex is situated near the centre of the Hageland and covers about 700 ha in the territory of the municipalities of Houwaart, Tielt and Sint-Joris-Winge. The greater part of these 700 ha is private property, but some smaller areas are owned by the semi-public 'Nationale Landmaatschappij'. The wood covers the Roeselberg, the Alsberg and the valley between this hilly region and the Brede Motte river (Fig. 2). In the north-east corner the boundary is formed by a brook, the Leigracht. The sources of the Brede Motte and a side-brook of the Molen-brook are in the marshlands situated in the valley. In the south-west corner the park of the castle of Kleerbeek links the complex to the valley of the Molenbrook, thus forming an integrated unique landscape covering about 10 km 2. The upper geological structure is Diestiaan (Pliocene), which consists of greeny coarse sands, with a cover of pleistocene, light, sand-loamy substrates. The soils in the wood are mixed and mostly very wet. In some areas a layer of peat is present and some peat-cutting in about 1930 has resulted in a number of fen-pits.
245
A CONSERVATION SITE OF N A T I O N A L I M P O R T A N C E IN BELGIUM
HOUWAART
install.
TIELT
Roeselberg
ST-
JORIS-WINGE 1 km
Heathland
Fen-pits - -
Fig. 2.
Boundary ~Roads
Map showing the main characteristics of the area.
MAIN BOTANICAl. CHARACTERISTICS
The most important botanical associations are of several different types, because the area includes both the hilly ground inthe south and the valley of the Brede Motte to the north. This results in numerous transition zones mainly from dry to wet biotopes. Most of these are oligotrophic and very poor in nutrients, Molinia caerulea Moench frequently appearing as an indicator of this condition. Natural succession tends towards an overall deciduous forest type, which together with open marshlands formed the landscape in former times. The last few remaining sites of
246
w. XlPS
heathland and the most valuable and scarce bluegrass meadow (Cirsio-Molinietum) in the valley are presently being overgrown by shrubs and trees. Little can now be done to save the bluegrass meadow and stop the succession to associations of Salicion cinereae because this stage is already too far advanced. Due to this process a number of butterflies (see below) have disappeared. The heathland sites which are also reduced to a very small area contain cross-leaved heath (Erica tetralix L.), heather (Calluna vulgaris (L.)), needle furze (Genista anglica L.) and broom (Sarothamnus scoparius (L.)) and can be classified as a Genisto pilosaeCallunetum. It is also in urgent need of careful management (see Fig. 3).
Fig. 3.
Heathland site at the Walenboscomplex in need of management.
A wet type of alder carr (Carici elongatae-Alnetum) is now the most characteristic vegetation type (Fig. 4). In those areas where the succession has reached the final stages or nearly so, there are forests of the Quercion robori-petraeae, mostly the association Querco-Betuletum molinietosum (oak-birch forest). Recent human influence has been responsible for much of these wet grounds changing to dry pine-forests with low biological diversity. In addition Canadian poplar (Populus x canadensis Moench) has been planted in some areas.
A CONSERVATION SITE OF N A T I O N A L IMPORTANCE IN BELGIUM
Fig. 4.
247
A l d e r c a r t at the Walenbos.
MAIN FAUNAL CHARACTERISTICS
Roelants (1975) lists a large number of birds including water rail (Rallus aquaticus L.), woodcock (Scolopax rusticola L.) and honey buzzard (Pernis apirorus L.) from the Walenbos. My own observations include long-eared owl (Asio otus (L.)) and buzzard (Buteo buteo (L.)). Apart from this general knowledge of the birdlife, little information is available on the fauna of the area. Among the best known are several uncommon butterflies. However, with the disappearance of the hay lands most of these species are no longer seen. In the collection of P. Halflants (Lubbeek) we found (Tips & Halflants, in press): white admiral (Limenitis camilla (L.)) (still present), marsh fritillary (Euphydryas aurinia (Rottemburg)), Glanville fritillary (Melitaea cinxia (L.)), spotted fritillary (Melitaea diamina (Lang)), heath fritiUary (Mellicta athalia (Rottemburg)), small pearl-bordered fritillary (Clossiana selene (Denis & Schiffermtiller)), pearl-bordered fritillary (Clossiana euphrosyne (L.)) and dark green fritillary (Mesoacidalia aglaja (L.)).
248
w. TIPS
Further biological investigations are being carried out by amateur biologists and the author.
THREATS TO THE AREA
Because its range of biotopes is of interest only to naturalists and biologists the Walenbos has been saved up to now from invasion by day trippers and from the effects of cultural eutrophication. However, as it is relatively unknown to the public the regional organisation Nature and Landscape VZW (Boutersem) has had to publicise the threats to the area, in order to arouse support from public opinion. Apart from the lack of management, there are two main threats to the future of the area. In the first place hunting activities each year result in a large area being cut out to create shooting positions. In the long term this will cause a general degradation and the destruction of valuable plant communities. Secondly there is the replacement of deciduous woodland by exotic species, mostly Corsican pine (Pinus nigra laricio (Poi.) Palibrin) and also the Canadian poplar. This type of change will be most unfavourable for the conservation of insects and birds characteristic of the Walenbos. Finally there is a possibility that the Walenbos will be used as a source of water for the region. There is already one minor pumping installation in the south-west corner and more intense pumping will, beyond doubt, be harmful to the wetter biotopes, such as the associations of alder carr (Alnion glutinosae), which are of national importance in Belgium.
LEGISLATION TO SAFEGUARD CONSERVATION AREAS
In Belgium there are several different ways of protecting valuable natural sites. In practice most of these procedures are inefficient due partly to lack of supervision and partly to the fact that responsibility is divided among different departments. Since 1962, the Ministry of Public Works has planned several 'green zones' in the 'Sectorial Development Plans'. The complex of the Walenbos is designated in the Sectorial Development Plan for Aarschot-Diest as both a "green zone' area and as a future nature reserve. The official statement accompanying the plan names it as a most important natural area. But although the legal procedure implies ratification by Ministerial Decree, followed by Royal Decree in 1977, full protection against agricultural and forestry activities is not guaranteed. Another protection method is "classification' as a Monument or Landscape by Royal Decree of the Ministry of National Education and Culture, which may be
A CONSERVATION SITE OF N A T I O N A L IMPORTANCE IN BELGIUM
249
applied to both private and publicly owned areas. Although the management of natural sites as reserves is possible by this procedure in practice this has never been realised by the government. Almost 300ha of the Walenboscomplex have been classified and another 300 to 400 ha will follow this year. During a period of nine months (the provisional classification time) preceding the decree, in which the integrity of the area is legally guaranteed, a number of serious violations have been recorded. In spite of the prohibition on all hunting activities, a battue has taken place. Again an area has been cut out to provide for shooting positions. Moreover serious damage was caused to the heathland remnant, by using part of it as a feeding-ground for pheasants. The ~Law on the Conservation of Nature' (12 July 1973) not only makes it possible to protect and manage natural areas as reserves but also interesting sites and landscapes for nature conservation purposes. In addition it provides for the management and supervision of the nature reserves by government personnel. Finally it is highly regrettable that there is no Nature Conservation Institute in Belgium up to the present time. According to the Law on the Conservation of Nature such an institute should have been founded two years ago. But the Ministry of Agriculture still refuses to take action under this section of the Law. Consequently field biology and research for conservation purposes in Belgium has to rely mainly on amateur biologists and private initiative.
THE FUTURE
It is obvious that the only effective way of conserving the Walenboscomplex is to make it an official nature reserve. Because several biotopes require management, for example the heathland site and all types of shrub biotopes such as the Carici elongatae-Alnetum, the present classification is not adequate. The designation of this area as an official nature reserve, as proposed in the Sectorial Development Plan for Aarschot-Diest, should be fulfilled as soon as possible, according to the Law on the Conservation of Nature. Although several hundred owners are involved in the proposed expropriation, this problem should not provide an excuse for failing to conserve an area as valuable as the Walenboscomplex.
ACKNOWLEDGEMENTS
I wish to thank Mr Pierre Halflants for his enthusiastic co-operation and Prof Dr S. G. Kiriakoff, Dr E. Kuyken, Mr A. Abts and Prof Dr H. Gysels for their help in several ways.
250
W. TIPS REFERENCES
ROELANTS,A. (1975). Het Hageland-Geologie-Bodem-Planten-groei-Vogels. Nu o[ Nooit, 5, 3-27. TIPs, W. & HALFLANTS,P. (in press). La collection entomologique de Pierre Halflants, notaire honorain/t Lubbeek (Gellenberg). I. Nymphalidae (Lep.). Linneana Belgica. VLIEBERGH, E. (1921). Her Hageland. Louvain, Davidsfonds,