CCF Group Study Tour to Holland
by L Heinz Traut
Conservation and Forest Ecosystems (BSc) student at the University of Wales, Bangor
In June 2005 I attend a CCFG (Continuous Cover Forestry Group) study tour to central Holland. Our base was in Harderwijk, north of Apeldoorn, with visits to the Royal Forest and State Forestry Service managed land within the Veluwe National Park. The tour also included an excursion to the Flevoland polder forests. The aim of the tour was to gain an insight into commercial and conservation management of Dutch forests.
Introduction |
Holland has 339,000 ha of forests – 10% of the total land area. Forest species composition is 43% broadleaved, 42% coniferous and 15% mixed. Private ownership is 49% and public ownership 51%.
The Veluwe National Park
is the largest nature and woodland area in the Netherlands (90,000 ha) and it is of significant cultural and historical value. 65% of the land area is covered by forest and woodland, 31% by heathlands and drift sands and 4% by agricultural land. Forest ownership is divided between the government (50%), nature conservation organisations (15%) and private owners (35%).
Altitude varies between 20 and 150 m above sea level and the mean annual and summer temperatures are 9ºC and 15ºC respectively. Average annual precipitation is 800 mm, of which 350 mm falls during the vegetation period. The geology consists of pleistocene river sediments; these sediments were pushed up during past glaciation events.
After the last glaciation, Scots Pine (Pinus sylvestris) and Birch (Betula spp.) forests established on the poorer soils and Sessile Oak (Quercus petraea) and Beech (Fagus sylvatica) established on the richer soils.
From around 2800 BC to around the 18th century, man’s impact on the landscape resulted in almost complete deforestation. The outcome was a man made heathland and drift-sand landscape, largely due to continual overgrazing. It started with nomadic people burning forest in order to obtain arable land, resulting in a landscape of open forests, shrubs and heathlands.
In the early Middle Ages permanent farm settlements were established. Fields were fertilised with sheep droppings, mixed with cut sods from the heathlands and forest litter. The high intensity use of the heathlands resulted in the destruction of cover vegetation, mostly in the higher and drier areas, and the exposure of the sandy loam soil to wind erosion. The windblown sand was caught in the damper, lower lying areas and therefore caused an inversion of the former cover sand. Some forested areas surviving as forests around villages were protected – no grazing, litter removal or illegal logging were permitted.
Extensive inland dune sands were formed by the late Middle Ages and by 1850 15,000 ha of the Veluwe consisted of drift sands, posing a great thereat to villages and arable land.The village of Kootwijk
disappeared several times under the drift sands. The collapse of the sheep market at the end of the 19th century was the motivation for large-scale afforestation and in 1899 the state forestry department,
Staatsbosbeheer
, was founded. Its purpose was to reverse the degradation of the landscape and to stop the drift sands by afforestation with Scots Pine.
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| Heathland now converted to forest |
In 2000, key stakeholders launched the Veluwe 2010 initiative to facilitate the sustainable future development of the area. Projects that have been realized include: the construction of strategically placed transferia – where visitors are offered parking, bicycle hire facilities and information centres; the restoration of 60 ha military ground, back to nature; the restoration and relocation of a 12 ha industrial park, in order to create a natural corridor for wildlife between the Veluwe and the Rhine floodplains (€36m project) and the construction of “ecoducts” across motorways and railways, which open wildlife corridors between geographical areas – plans are in place to build more ecoducts (seven in total). The Veluwe 2010 project is ongoing.
Royal Forests in Apeldoorn |
Our host for the day was Jaap Cooper, head forester for the 10,500 ha (100 m elevation) royal estate within the Veluwe National Park.This was the first forest in Holland to receive FSC certification.
The estate was originally established to serve as a royal hunting lodge. The sandy heather fields were mass-planted with Scots Pine (from North German provenance). This native species (SP) was used due to its ability to grow in this harsh environment. It would, in due course, create a more suitable microclimate below its canopy for other tree species. Afforestation was accomplished between 1855 and 1911. Today, Douglas fir (Pseudotsuga menziesii), Japanese Larch (Larix kaempferi), Sessile Oak (Quercus petraea), Pedunculate Oak (Quercus robur), Beech (Fagus sylvatica), Rowan (Sorbus aucuparia) and Birch (Betula spp.) have established through reintroduction (sown and planed) or natural colonisation. In areas where SP was not planted birch, Oak and Beech have invaded.
Current objectives for the estate are to manage its woodlands for the purposes of hunting, timber production, landscape value and nature conservation.These objectives are sometimes conflicting. A zoning system was implemented whereby 15% of the land area was designated as indigenous woodland with no harvest intervention, 75% indigenous woodland with intervention and 20% mixed exotic woodland with intervention.
Since 1985 a continuous cover forest system has been adopted, except for the areas planted with exotic species (Douglas fir). Hence, harvesting is done by selective felling.
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| An ecoduct over a motorway (measuring 35m wide and 50m in length) - built at a cost of €2.5m. |
The estate’s current policy is to put no more investment into its forests, but only to intervene to control the quality of future (frame) trees. 100 future trees per hectare are selected, based on tree stability, and poor quality trees are thinned out.
Future trees are individually marked by the estate foresters and harvested when a suitable net present value (NPV) is achieved – normally between 35-40 cm DBH. The average estate yield class is estimated to be YC7 and an average of 50 m³ ha is harvested every 10 years. Exotics are thinned every five years. It is estimated that only two thirds of the estate’s increment is currently harvested.
In general, the form of the trees seemed relatively poor compared with UK standards. Timber is sold for between €5-10/m³ standing and €30/m³ at roadside for firewood. The estate sold 35,000 m³ of timber during 2005. The estate also has a nursery that supplies plants for export. The forest is open to the public for recreational purposes and this allows the estate to benefit from additional income through grants, though the estate would still be profitable without this income. Income is also generated from the estate restaurant and hunting licence fees. As there is no investment into the forests, there is minimal intervention (e.g. no pruning), purely due to economics. In the past, scarification was done to encourage natural regeneration, but high costs (€150/ha) did not make it viable to continue with this practice. No additional planting is done. By controlling deer numbers, natural regeneration is more successful.Wild boars are not an issue as their density is controlled by mast years. The overall impression was that the estate enjoys economies of scale, plus income from various minor sources, and can therefore afford not to invest and still be a profitable enterprise.
State Forestry Service in the Veluwe |
Our host for the day was Eric Klein Lebbink of the state forestry department, Staatsbosbeheer. The department owns around 10,000 ha of the Veluwe forest. Our excursions included visits to
Kootwijk
(the Dutch desert) andSpeulderbos
(the forest of the dancing trees).
Kootwijk
 |
| Forests at Kootwijk in the Veluwe. |
Between 1900 and 1930 the focus was on soil protection and drift-sand control to protect villages and agricultural land; until 1960 the aim was timber production for the coal mines and today objectives include timber production, conservation and recreation. The target for deadwood is 10 to 15% and 10% of the area is maintained as open space to encourage biodiversity. This includes 600 ha of the Kootwijk forest being maintained as a drift-sand ecosystem, due to its cultural importance, characteristic pioneering flora and fauna species and for recreational value.
The drift-sand has to be actively maintained, as the natural succession would be bare sand, bentgrasses, mosses and lichens, heathland and then Pines. Since the 1960s, nitrogen deposition has increased the vegetation succession rate, hence management, such as rotary cultivation, is required to retain a dune ecosystem. Our first stop was at an observation tower on the edge of the dune reserve. It was constructed for educational reasons and offered a view across the Pine forests and dune systems.
The second stop for the day was Pine afforestation sites (vak 37 & 38), also in the Kootwijk forest, established between 1900 and 1950. Management plans for these compartments are aimed at improving stand structure – encouraging natural regeneration and ultimately, uneven aged structure. Actions have included removing exotics (Fir and Larch), small clearcuts in the 80s and ringbarking and felling clusters of trees in 2002. The success of these actions is yet to be determined, and the future influence of red and roe deer also needs to be considered. In recent years cattle have also been permitted to graze in some parts of the forest. The area is prone to summer fires and the necessary infrastructure (fire trucks, helicopters and aeroplanes) has been established. It is evident in some areas of the Pine forest that native trees, such as Oak, Black Cherry (Prunus serotina), Rowan, Elder (Alnus spp.), Birch and Juniper (Juniperus communis), have started to establish due to the favourable microclimate created by the dominant Pines.
The third stop was at a multifunctional forest at
Garderen Schaapskooi
, originally a heathland planted in the 1930s, and where first and second generation forests are present. There are two types of multifunctional forests and two nature-dominated forests. The objectives are timber production, recreation, conservation, landscape enhancement and cultural values. Management practices include selective felling (based on diameter), thinning to favour stand structure and mixture, use of natural regeneration instead of artificial regeneration, the retention of a minimum percentage of deadwood, conservation of older trees and wildlife management (based on habitat features rather than hunting regimes).
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| The Kootwijk dune reserve |
The second multifunctional forest consists of SP, Larch, Birch and Oak. The objective is to attain 80 to 100 frame trees per hectare.
Trees to be thinned are marked by state foresters and the aim for basal area, after thinning, is 20 m² ha. No pruning is done due to economics. Performing forest inventories every 10 years monitors the production quality. The selling price for timber is on average €25/m³.
The forests are also open to the public and waymarked paths for walkers, cyclists and equestrians have been constructed.
Speulderbos
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| A 150 to 200 year old Beech-Oak forest in the Speulderbos - the crooked form of these trees is due to centuries of negative selection. |
In 1855 the land belonged to a monastery, which permitted farmers to graze their cattle. However, due to overgrazing, litter collection and harvesting of the best-formed trees, the forest became degraded.
In 1875 the right to graze ceased and parts of the forest was turned into coppice. The forest was then used for hunting. In the early 1900s Douglas Fir and Japanese Larch were planted within the Oak-Beech forest. In 1918 the Speulderbos became a state forest and the Staatsbosbeheer replaced large areas of coppice with fast growing softwoods – Douglas fir, Japanese Larch, Corsican Pine (Pinus nigra), common fir (Abies alba) and grand fir (Abies grandis).
Current management plans have divided the Speulderbos into four zones. The nature dominant forests, in the central zone, have native trees such as Beech, Oak, SP and Birch – they have an estimated stocking of 400 m³ ha-1. All exotic species (e.g. Douglas Fir and Larch) are systematically being removed and where clearcuts are necessary, Oak (Quercus petraea) and some Beech are planted – with fencing.
Occasionally Beech is ringbarked to favour Oak trees. The nature forests have no timber production function and are purely for recreation and conservation use. There are a number of multifunctional forest compartments, all with different species mixtures, ages and management plans. Here the objectives are recreation, conservation and timber production.
Some of the species present include Beech, Douglas Fir, Larch, SP, Sitka Spruce (Picea sitchensis), Birch and Red Oak (Quercus borealis). Both natural regeneration and enrichment planting are used where thinning or storm damage has taken place; planting is normally combined with short-term fencing. Thinning is performed every four to eight years, once trees reach 40 years of age.
Typically 50 m³ ha is removed when thinning every eight years. Some pruning is done on the younger Oak trees to encourage favourable form. Stocking ranges between 260 and 280 m³ ha and the yield class between 7 and 9 (m³ ha yr).
The Flevoland Polders |
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| Extraction of 47 year old Poplar |
The polder forests are unique as no afforestation projects had ever been done on former ocean floors. The first was in 1942 on the Noordoostpolder.
After the First World War the idea of reclaiming the Zuyderzee was born. In 1932 the Afsluitdijk was built, which turned the Zuyderzee into a 200,000 ha freshwater lake. About 165,000 ha land have since been reclaimed from the sea, which include four polders, of which two are the North and South Flevoland Polders. The aim of the project was to make more land available for urbanisation, industry, agriculture, forestry and recreation.
To create a polder, the area had to be enclosed with dikes, the water pumped out, canals and subsurface drainage systems constructed, the soil improved and the infrastructure engineered.
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| Drainage canals between forest compartments on the polders. |
The south-eastern part of the Flevoland polder is dominated by extensive forests. For example, the southern polder (44,000 ha) was allocated 10,000 ha for afforestation projects.The objectives of these forests are timber production, recreation and conservation.
The average ground water level in the forest varies between 0–40 cm below the surface in winter and 50-120 cm in summer. Typically, drains are 1.20 m below the surface and spaced between 8-24 m apart – spacing dependent on site-specific conditions – and lead into adjacent canals.
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| Map of Holland with markers pointing out the location of the polders and the Veluwe (Printed with permission from Staatsbosbeheer, Directie Oost). |
The Poplar and Willow produced between 17-30 m³ ha yr. The Oak, Ash, Beech and Sycamore produced an annual increment of 10 m³ ha. The Spruce and Pine suffered under attack from Heterobasidion annosum and Armilaria spp., which thrived due to the high lime content of the soil. Some of the fast growing species have also been lost to storm damage, exacerbated by the soil and water conditions and tree root structures.
First stop: A Poplar and Alder stand (mixed with Birch (B. pubescens) and Sycamore) planted in 1958, which was thinned (50%) in 1970 and again (50%) in 1975. It was noted that bird life developed quickly in the fast growing Poplar stands. In 1985 Q. robur was under-planted. The Poplar that has recently been harvested (2006) was sold for €50-60 m³ as veneer quality timber.
Second stop: Corsican Pine and Birch planted in 1958 at 1x1 m spacing. Thinning of Pine took place in ’67, ’72 and ’73 at 50%, 20% and 15% intensity respectively. The Pines suffered from Armilaria and H. annosum attack. In general, the timber quality and form is poor and sales have been at €10 m³. Natural regeneration has been good for Birch, Oak, Cherry, Rowan, Ash and Sycamore.
Third stop: A former Poplar plantation (planted 1970) under-planted with Oak and Ash in 1972, Sycamore in 1977 and Lime in 1981. Most Poplars have been harvested and the remaining species have achieved a yield class of 11 on a fertile soil.
Conclusion In the last decade Dutch forestry has seen a turnaround in policy.Timber production is no longer the main focus, but the benefits that forests/woodlands bring to society and the habitat created for wildlife have become more important.However, more timber is being harvested compared to recent years, as harvesting has been below the annual increment. The important change is that there is now a policy of following natural processes rather than large-scale interventions, such as clear-cuts.This has also brought savings in management costs. Natural and integrated forest management is the goal; this translates into the use of site-adapted species, natural regeneration, small-scale (selection) logging and management of dead trees.These measures are aimed at enriching the structure of the forest, as well as making it more resistant to storm damage. Finally, it is with gratitude that I thank |