Woodland Structures

I'd previously never thought too much about the structures of woodlands but I can now see the different structures and how they work and how they are different in the species that they have - because of the particular structure they are.

Woodlands can be looked at in reference to both their horizontal and vertical structures.

The horizontal structure of British woods is looking at how dense the woodland is - how close together the trees are.

Trees may be wild and cramped together forming dense woodland in contrast, when woodland is closely managed and planned, trees can be evenly spaced.

The location of the forest can impact on the denseness and distribution of the trees; alongside environmental aspects including: drainage, moisture, soil type and whether it is flat or on a slope.

Woodlands can change relatively quickly following rom large trees dying and areas being cleared to then have saplings flourish; creating different areas within the woodland.

Wild / cramped together

Evenly spaced

Evenly spaced with gaps

Uneven with gaps

Looking at the vertical structure of vegetation, working upwards the first layer – often taken for granted, is the ground layer. This layer, which is less than 2cm from the ground, consists of mosses, lichens, ivy and fungi. Alongside this on the woodland floor there are rotting leaves and vegetation; a microhabitat for invertebrates – including woodlice and centipedes. We have all of these at our forest school site – but you may needs to look closely! There are some lovely examples of fungi on the tree stumps of the cut down trees – it smells very mushroomy! Children should be reminded of health and safety when exploring; some fungi is poisonous and some children can have an allergic reaction to ivy.

The next layer up is commonly called the field layer – which comprises of vegetation between 2cm and150cm. This layer is home to ferns and flowering plants, including wood anemone, horse tails and lots of different grasses. It can often be thought of grass as all being the same but it can be a lovely activity for children to identify similarities and differences between the different grasses in our forest school – ‘Forest School Vision’ needed!

Above the field layer is the shrub layer – ranging from 1.5 metres to 4.5 metres. This layer is composed of shrubs which are happy to grow in limited light. These include: blackberry, elder, hawthorn, hazel and field maple – these can all be found in our Forest School area. Alongside these could be sapling from canopy trees. This layer provides a wealth of shelter and food for a wide-range of mammals, insects and birds.

Finally the highest part of the British woodland is the canopy layer – which is roughly anything over 4.5 metres. This is the realm of the dominant trees: oak, ash, beech and birch (for example). These tree receive the maximum amount of light available and therefore control the climate beneath them in the lower layers of woodland.