Woodland Ways

Teachers' notes

Focuses on the range of plants and animals present in the woodlands, their adaptations to the places they live, how they live, and how they are connected.

This activity explores the differences between native woodlands and conifers planted by man.

The essence is that native woodlands provide habitats for a wider variety of plants and animals than plantation forests and, therefore, are more valuable for wildlife and have a higher biodiversity value.

Native woodlands and biodiversity value

Since the last Ice Age, different plant and animal species have been able to adapt to woodland conditions. Different plant and animal species are found in different woodland conditions. The type of woodland that occurs under natural conditions depends on the climate and the soil. For example, in much of lowland Scotland oak woodland is the natural woodland climax vegetation. In many Highland areas, where the soil is more acid and well-drained, Scot's pine forest develops. Much of the woodland in Scotland is planted, often with species that do not naturally occur here. These plantations do not develop in the same way as natural woodland and, as well as having different tree species they have different, often much simpler structure and fewer plants and animals can live in them.

Woodland structure

Native woodlands have a recognisable structure, although it is not always possible to identify each layer clearly.

The ground layer is made up of the shortest plants, such as mosses, dead leaves, stems of other plants, and fungi (toadstools). The herb or field layer is made up of taller grasses, ferns, herbs and tree seedlings growing up through the ground layer. The shrub layer consists of taller plants again, which are often woody and have many stems, these shrubs include hazel, gorse, and broom. Brambles may also be found in this layer. The tree layer is made up of the single stems and canopies of our largest, and most amazing plants - trees.

A plantation forest in its early stages does not develop this structure because not enough light can get through the canopy to the layers below.

Woodland structure is a very important factor in determining the biodiversity value of a woodland or forest. The greater the variety of structures provided by different plants the more different kinds of plants and animals may be supported.

Native woodlands today often need management because they are, or have been, threatened. Grazing by sheep and deer kills tree seedlings and can kill young trees and the woodland can become dominated by old and dying trees. Non-native tree species can also invade and take over from native trees. For example the seeds of conifers planted near to native woodland can establish and may eventually take over from the native trees. Some introduced shrubs, like rhododendron can also take over native woodlands in this way.

Conifer plantations and biodiversity value

Nature conservationists, particularly in the past, didn't like conifer woodlands because of their negative impact on the native wildlife and because plantations were often stark blocks that cut across the landscape and detracted from its natural beauty. Until about 20 years ago, plantation woodland was managed solely for its timber and the economic return this might bring.

Forest management has changed a lot recently and it has been recognised that forests are places for both people and wildlife. Forest Enterprise manages forests for timber and other purposes, such as recreation and the landscape, and its management also improves its wildlife value.

Many new woodlands have been planted in recent years throughout Scotland but these new plantations are often different to the single-species blocks of the past. Native tree species may be used, there is much more open space and the trees are planted sensitively in the landscape. Management of existing conifer plantations now also takes account of the landscape and conservation value of the woodland as well as the economic value of their timber.

Planting trees, whether they are native species or non-native conifers, brings changes to the wildlife. Birds that prefer open moor or grassland quickly disappear but some of our native birds are able to cope well in conifer woodland. Siskin, green woodpecker, crossbill, woodcock, willow warbler and goldfinch all cope well in planations. Red squirrels also do better if there are plenty of conifers around, whether they are planted or not.