We know how much woodland already exists in the Chew Valley but how much additional woodland could there be? How much, that is, without displacing valuable agricultural production or destroying biodiverse habitats? Is there a niche within the Chew Valley that could satisfy these criteria whilst also allowing woodland area to double?
In looking for space where woodland might be created we can identify the following criteria:
- New woodland should not displace arable land that should be used for growing food crops. It probably goes without saying that we need to be growing more food rather than less
- New woodland should not displace biodiverse grasslands that provide a rare habitat
- Similarly new woodland should not displace other important habitats for species of features that are protected
These are the three basic criteria but there are numerous caveats that go with them.
All Grades of land may have pockets of steep land where arable agriculture is difficult or inappropriate. In this scheme only poor and moderate quality land (Grades 3b, 4 and 5) that is not protected in some way and which is not arable land is identified as opportunity woodland, i.e. land that may be considered suitable for conversion to woodland by its marginal nature.
Examination of the maps shows that the opportunity woodland tends to nestle into the existing landscape and often occupies a similar niche to remaining ancient woodland. In his PhD thesis on the ancient woodlands of northern Somerset John Knight concluded that:
“The vast majority of ancient woodland cover was found to be on steep slopes. The location suggested a deliberate policy of defining land-use zones within each parish, the woodland being restricted to, or encouraged to regenerate on, areas difficult to farm or far from the settlement.”Knight, 2004
Woodland creation in these marginal niches may therefore represent the partial restoration of a more ancient landscape. We can identify these landscape niches using digital maps of the terrain, existing woodland, protected areas, land cover and agricultural land classification.
The more detailed Methodology page describes the method more fully.
Knight, J, 2004, The landscape archaeology of the ancient woodlands of northern Somerset, PhD Thesis, Bristol University