Overview of research design
Birchwood was selected as a case study because, in Britain at least, it is the largest and most radical example of the ecological woodland approach. The principal research instruments were a postal questionnaire, and a series of semi-structured interviews with a sub-sample of the questionnaire respondents. The sampling strategy was to obtain a random stratified sample. The strata were nine “housing character areas” (“HCA’s”) representing a typology of different residential areas in Birchwood, with differing vegetation and housing densities. There was also a “control” sample drawn from three HCA’s outside Birchwood (the method of selection of these HCA’s is outlined below).
Identifying the HCA’s
Birchwood is not a homogeneous entity. The residential part alone encompasses a variety of housing tenures and types, in diverse layouts. The amount of vegetation varies considerably from one area to another and in some parts, the woodland is very closely integrated with the housing (Fig. 1). It seemed possible that these differences would have an impact on public perception of the research issues. For these reasons it was decided to develop a typology of the residential areas in Birchwood that would reflect these differences. This typology was then used to select the areas from which the questionnaire sample and the interviewees would be drawn, using the vegetation density and the housing density of the areas as the criteria for selection. These two criteria were chosen because they were considered to be the main overall differentiating factors between the various areas. It was considered that housing density was the best indicator not only of the spacing and layout of dwellings, but also of their size and type.
Fig. 1. In some parts of Birchwood the woodland is closely integrated with the housing
Vegetation density and housing density
The HCA’s were identified by means of an urban landscape character assessment of Birchwood. The vegetation density of each HCA was measured using a technique derived from small-scale vegetation mapping and measuring techniques, based on the work of the ecologist Braun-Blanquet (Kent and Coker 1992). The area of each HCA in hectares was divided by the number of dwellings it contained to give a figure for housing density measured in dwellings per hectare.