Ecological sustainability assessment methodology

Calculating the biocapacity of the South West

To estimate the South West's biocapacity, three steps were followed:

  1. The various area types within the South West were defined and aligned with a yield class used in the National Footprint Accounts to find the relevant yield factors.
  2. The yield factors were then applied to each area type to give South West bioproductivity in terms of global averages. The yield factors take into account the differences between local bioproductivity (only UK factors were available) and average global bioproductivity for each resource type (see Table 11).
  3. The different land types were then converted into global hectares (gha) using National Footprint Accounts equivalence factors. The exception to this process was the calculation of sea biocapacity, where the UK average is retained.
Table 11
South West area types, by hectares, with associated UK yield factors
Yield Class Of which...* Ha in the South West Yield factor Equivalence factor
Arable Arable & horticulture 536,572 2.44 2.18
Pasture Grassland 1,173,462 4.57 0.47
  Dwarf shrub heath 33,275 4.57 0.47
  Fen, marsh, swamp & bog 18,941 4.57 0.47
Built land Inland rock 2,093 2.44 2.18
  Built land 240,834 2.44 2.18
Forest Woodland 293,009 2.26 1.35
Total 2,298,186  
Note: Excludes the South West's water area of 46,857 ha, as this data is not used to calculate sea biocapacity.
Source: ONS 2001a