Catalogue description Forestry Commission: Censuses of Woodlands: Reports and Data

The 1924 Census survey, which covered both private and Forestry Commission woodlands, was based on questionnaires sent to individual woodland owners who recorded acreage, and distribution by forest type and age.

The original intention of the 1938 Census of Woodlands was to obtain information on both area and volume of woodland, by surveying all woodland of five acres or more in extent, whether private or state-owned, a sample of woods between one and five acres, and a sample of hedgerows.

By the outbreak of war in 1939, however, only 21 counties had been fully surveyed and a further 11 counties partially completed, covering approximately one third of the total woodland area. In order to complete the survey quickly, the results for the unsurveyed counties were calculated by applying multipliers based on the known changes in area since 1924 in the counties which had been resurveyed.

The progress of wartime felling was so rapid that a new survey, the 1942 Census, was soon required in order to provide an up-to-date picture. In Scotland this was accomplished by carrying out a complete stocktake of timber stands, recorded on one-inch Ordnance Survey maps; in England and Wales, where the woods are smaller and more diverse in character, a sampling scheme was used.

Two independent samples, termed the"A" and"B" schemes, each consisting of five per cent of the total land area of England and Wales, were selected on the basis of one six-inch Ordnance Survey sheet in every twenty. In addition, certain areas of particular importance for timber production were surveyed completely; this constituted the"C" scheme.

The war-time fellings had a profound effect on the structure of British woodlands, and a new survey was undertaken, the 1947-1949 Census of Woodlands, to assess their full extent. Every wood of five acres or over in extent was assessed, whether in private or Forestry Commission ownership, and volume measurements were taken in a proportion of them. This was the most intensive woodland survey ever carried out in Great Britain

In the 1938 and 1942 surveys, the assessment of hedgerow volume was carried out concurrently with the main woodland survey. In the 1947 Census, however, the hedgerow survey was delayed until the main census had been completed and was then combined with a sample survey of woods between one and five acres in 1951. 441 six-inch Ordnance Survey maps were selected at random, and part of each sheet assessed for small woods and for hedgerow timber.

From 1952, in order to keep the records as up-to-date as possible, a process of cyclical revision was started, whereby about one fifteenth of the country was resurveyed each year. All woods of five acres and over were assessed, whilst woods between one and five acres and hedgerow timber were sampled. In all, fourteen counties in England and Wales had been completely surveyed before the system was discontinued, since the county was found to be unsatisfactory as a basic sample unit.

The 1979-1982 Census' aim was to take stock of the timber reserves of Great Britain, and to assess the environmental status of trees in rural and urban areas. The census was based on a system of sampling, and included all trees except those in Forestry Commission (FC) forests and Dedicated and Approved (D and A) woodland, for which data was already available.

The survey was divided into two parts: woodland (0.25 hectare and over) and hedgerows, park trees and clumps (under 0.25 hectare). The basic sampling unit was the county in England and Wales, and the district in Scotland.