Guidance Forest and woodland

Index section Forest and woodland

Introduction

The Dutch word bos covers both forest and woodland. In general, the Dutch prefer to speak of forest rather than of woods. The definition of closed forest used is a closed canopy and a crown projection (i.e. the ground cover as viewed from above) of at least 60%. None of the woods and forests in the Netherlands are ancient; most have been planted, but there is some spontaneous generation of forest in heathland, marshes, bogs and swamps. Young woodland of this type accounts for seven percent of the total area of forest.

Area of forest

The present (2000) area of forest is estimated to be 360 000 ha; compared with 1833, this is an increase of over 90%. The amount of forest in the Netherlands is continuing to increase. The forest and woodland in the Netherlands consists of a few large forests and many small woods.

Forest management

In the past, forests were primarily exploited for timber and tannins, and used to graze livestock and to hunt game. To supply timber, monocultures (i.e. stands of a single species) were planted and then clear-felled after a relatively short time. Many of the tree species planted were fast-growing exotic species; these survive in many places. Nowadays, two important factors considered when planting and managing forest are the forest's potential for recreational use and its value for nature conservation. This is why the current practice is to plant more indigenous deciduous species rather than conifers or exotic deciduous species. The changes in forest management have repercussions on the flora and fauna, including the insects. In the past there used to be problems with pests on coniferous trees; nowadays, the pests attack mainly deciduous trees. .

The maturing of forest

In the last thirty years, the average age of Dutch forests has increased. There are therefore more birds of older forest than was the case in 1950. And birds of prey are also more numerous than in 1950. The older forests have closed canopies and are darker; there are few gaps created by fallen trees because most forests are still too young. Canopy closure is disadvantageous for butterflies, because these require clearings, wide forest paths and wide forest margins.

Eutrophication, the effects of water draw-down and acidification

The forests on the higher-lying sandy soils are particularly at risk from eutrophication and the effects of water draw-down. Eutrophication encourages the proliferation of nitrophytes such as nettle, bramble, climbing corydalis and cleavers.

The decline in certain woodland birds on the higher-lying sandy soils is possibly attributable to the effects of water draw-down and acidification. Certain butterflies are also suffering from the effects of water draw-down. And these effects, together with acidification and eutrophication are also affecting the forest fungi. Recently there seems to have been a resurgence of fungi, possibly because of the improved environmental quality. Acidification and eutrophication probably also affect the trees' vitality, but forest health is not at risk.

References

Al, E.J. (red.) (1995). Natuur in bossen. Ecosysteemvisie bos. IKC Natuurbeheer. Wageningen.
Directie van de Landbouw (1876). Verslag van den landbouw in Nederland over 1875. Supplement grootte der gronden tijdens de invoering van het kadaster. Directie van de Landbouw. Den Haag.
Dirkse, G.M., W.P. Daamen en H. Schoonderwoerd (2002). Het Nederlandse bos in 2001. Expertisecentrum LNV. Wageningen.
Liebrand, C.I.J.M., M.J.M.R. Vocks, A.A.M. de Goeij en M.C. Scherpenisse-Gutter (2000). Tweede opname van de ondergroei in het Meetnet Bosvitaliteit. EurECO-rapport 44. Nijmegen.
Paasman, J.M. (1997). Achtergronddocument evaluatie bos. Natuurverkenning '97. IKC natuurbeheer. Wageningen.