5: Canopy cover

What information does the survey provide and why does it matter?

In this measure ‘canopy cover’ is the overall percentage of the area with vegetative cover of any woody layer ranging from established regeneration to mature and veteran stages, (but visible regeneration is excluded as it is not yet established and so does not form part of the canopy).

Woodland canopy density and structure is an important driver of ecosystem function and the services that woodlands provide. Microclimate, litterfall, soil moisture, nutrient turnover and shading are influenced by canopy cover for example; this in turn shapes the living communities in lower vegetation layers and soil.

Canopies with scattered trees and low cover will have less of a woodland character and reduced diversity of woodland-dependent species (although they may be valuable as wood-pasture if they have a history of this form of management: see area of native woodland, and below). Completely closed canopies across the whole woodland are not ideal either however, as they support few species associated with edges, glades and open grown trees, and have little space where tree regeneration could occur.

In general areas within the range of 50-90% canopy cover in the survey should have a good balance: a core of woodland interior conditions with some open and edge habitat as well. Canopy cover in the range of 50-90% is one of the 4 components of the native woodland condition indicator (see native woodland condition indicator).

This range of cover should also be able to supply a range of other woodland services/values including wood products, a woodland recreational experience and scenery, soil and water protection and carbon sequestration.

This generalisation should not be turned into standard targets or prescriptions for individual sites. Open native woods with less than 50% cover may be valuable as wood pasture or parkland, or as historic landscapes for example. Site management objectives need to be set on a case-by-case basis.

Policy relevance

Canopy cover relates to capacity to deliver a range of other values as well as biodiversity (see above).

How can the NWSS data be used?

Type of useNationalRegional/local authorityLandscape/site scale
Native woodland condition indicator calculation Yes Yes n/a
Assess possible need to regenerate or restructure canopy Yes Yes Yes