Can you see the open ground and brambles?
This patch of land used to be used for growing vegetables but is now used less enthusiastically! If bare land is left alone 'ecological succession' will take place.
This is the change in species composition over time as available resources change. The natural process by which one habitat turns into another i.e how a bare field turns into woodland. 40 years ago Snowdrop Wood (the woodland you see in front of you) was a field, much like those that surround it, but thanks to people leaving it alone and the phenomenon of ecological succession, it is now a young woodland.
The first species to grow on a recently bared area of land are known as pioneer species and include bramble and nettles. Ash and birch are also pioneer species.
Bramble and nettles are also often found in the shrub layer of broadleaf woodland. This layer contains mostly woody plants that grow from roughly knee to head height.