Ancient and semi-natural woodland and protected areas
The information in Table 4.2 and most of Table 4.1 has been reproduced from Protected Forest Areas in the UK (S Pryor & G Peterken, 2001) (not National Statistics). It has been derived from a variety of sources, and is unlikely to give a wholly accurate inventory of protected areas in the United Kingdom.
The woodland categories used in Table 4.1 are:
- ASNW: (ancient semi-natural woodland) both ancient and semi-natural.
- PAWS: (plantation on an ancient woodland site) ancient in the sense of continuously wooded over a long period but not semi natural.
- OSNW: (other semi-natural woodland) semi natural but not ancient.
The types of statutory protection in Table 4.2 are:
- SAC: Special Area of Conservation;
- NNR: National Nature Reserve;
- SPA: Special Protection Area;
- SSSI: Site of Special Scientific Interest (ASSI in Northern Ireland).
Data about the small amount of ancient woodland in Northern Ireland was not available in 2001, but has been added using the report Back on the Map (Woodland Trust, 2007).
The UK Indicators of Sustainable Forestry (indicator B1) published in 2002 used results from a different source: Pryor & Smith (2002). This was an updated estimate of ancient woodland area derived by overlaying the NIWT 1995-1999 digital map onto ancient woodland inventories. This gave lower figures than those published in Pryor & Peterken (2001). At the time, Pryor & Smith (2002) was thought to give the best estimates of ancient woodland area. However, further investigation of the discrepancies between NIWT and the ancient woodland inventories suggests that some discrepancies are due to differences in spatial registration of woods, and that some areas of ancient woodland are incorrectly omitted from the totals in Pryor & Smith (2002). In consequence, the estimates from Pryor & Peterken (2001) are now recommended for use, until better information becomes available.
The Ancient Woodland Inventory data sets for England and Wales are currently being revised. New estimates for Scotland will become available from the Native Woodland Survey of Scotland.
The information in Table 4.3 is taken from inventory and projections of UK emissions by sources and removal by sinks due to land use, land use change and forestry (CEH, 2008), contributing to 2006 UK Greenhouse Gas Emissions (Defra, January 2008). The figures for removals due to land afforested since 1990 exclude the increasing pool of carbon in timber products.
Figure 4.2 shows annual estimates of carbon sequestration by country, taken from the same source but shows carbon in living forest biomass only; it excludes carbon in litter, soils and forest products. Future predictions of carbon uptake assume that commercial conifer plantations will be replanted when felled, and that planting of new woodland will continue at the same rate as in 2006.
Populations of wild birds
Population indices for wild birds are a framework indicator for sustainable development. The data published here are based on those published by Defra in November 2007, rescaled here to give year 2000 = 100 instead of year 1970 = 100. Further data and analysis about populations of wild birds are in Defra Wildlife KeyFacts.
The index for woodland specialists was recalculated in 2007 to include 4 additional species; this affected the indices for total woodland birds and (to a lesser extent) all birds.
This indicator, which shows the overall condition and richness of flora in woodland, is derived from data collected in 1998 for the Countryside Survey 2000. The Countryside Survey is carried out at intervals of about 8-10 years; the next was in 2007, with initial results to be published in late 2008.
CS2000 did not contain sufficient monitoring plots for Wales to be analysed separately. No similar samples were taken in the Northern Ireland Countryside Survey.
Broadleaved scores are based on 195 sample ‘x’ plots in CS2000 in GB. Broadleaved change scores are based on the 131 plots that were in the same woodland broad habitat in 1990 and 1998.
Conifer scores are based on 170 sample ‘x’ plots in CS2000 in GB.