Looking at Layers

Source: 

Adapted from the Taynish National Nature Reserve, local schools pack (SNH)

Time

30 minutes 

You will need

• notebooks & pencils
• an area of plantation woodland where all the trees are of a similar height, age and species
• an area of semi-natural native woodland

Did you know?

Many of the best examples of our native woodlands are now nature reserves. These woodlands have a much greater structural diversity than commercial plantations of trees.  Beinn Eighe, Glen Affric and Abernethy Forest National Nature Reserves are excellent examples of woodland habitats that may be interesting to study.

Before the Activity

Discuss woodland structure and the different ‘layers’ as listed in the Activity section. 

The Activity

Gather the class together in an area of diverse woodland structure. Discuss woodland structure and see if they can identify and describe the following layers previously explained in the classroom:

• canopy (highest trees)
• sub-dominant layer (smaller trees and saplings) 
• shrub layer (bushes and woody plants- e.g gorse, bramble, juniper, heather, blaeberry)
• herb layer (grasses and non-woody plants)
• ground layer (creeping plants, mosses and lichens, leaf litter)

Let each pupil draw a rough diagram of the different layers. It doesn't have to be very accurate or to scale, just illustrative of the different layers. The pupils can then decide which is the dominant species in each layer and add these as labels to their diagram. In addition, can they spot any plants which reach the canopy that are not trees? (the climbers - like ivy and honeysuckle).  Can they see any standing or fallen dead wood? Is this a valuable resource? What could it be used for?

See if they can spot any birds, mammals or minibeasts and make suggestions as to which layer or layers these animals would use either for foraging for food or for nesting/resting.  For example: tits and tree creepers  are found in the canopy and upper shrub layer, wrens in the lower layers, dung beetles and centipedes in the ground layer. A squirrel would use all the layers except the herb layer and some insects would just use the herb layer. Spiders might be found in all the layers, however, the species found might vary considerably in the different layers.

Repeat the activity in a second area that has a less diverse structure, such as a commercial plantation. Get the class to list the reasons why plantations will be less valuable to wildlife (biological diversity - biodiversity), than natural woodlands. Look at aspects such as the age range of the trees (hollow branches and trunks provide nest sites; mature trees provide more fruits; young trees allow more light to reach the lower layers and provide more shelter and more leaves and shoots to eat nearer the ground), the number of different species of trees, the amount of sunlight reaching each layer.

Suggested Follow up

Investigate the minibeasts living in the layers, see Minibeast Detectives in the Biodiversity section.  Record the species found in the different layers and also the relative numbers of each species found.  It is not necessary to know the name of each species found, they could be called beetle1 or caterpillar A etc. You might find that spiders are more common in one layer and caterpillars or beetles in another.

Downloads

• Information on native trees, their folklore and their uses Trees for Life, 
• Information on  native trees in Scotland
• woodland plants 1
• Woodland plants 2

Additional Information

• A Tree Name Trail from Forestry Commission
• The Field Studies Council makes a laminated fold-out tree guide of common tree species.

Curriculum Links

Science (main)

Age Range

2, 3