HABITAT SURVEYS IN UPLAND AND LOWLAND STUDY AREAS 
Because aerial photographs would seem to be the only practical means of 
collecting ecological information rapidly, over large areas, it is necessary 
to 
(a) examine the main types of data used in conservation evaluation in 
terms of air photo capability 
(b) assess to what extent the collection and evaluation of these data 
can be made objective. 
With these aims in mind, two large areas one upland, one lowland, were 
chosen according to the availability of suitable air photo cover. Habitat 
surveys were carried out over each area and wildlife habitat maps were 
produced. (Figures 1 and 2) 
The upland study area - Gairloch 
This comprises approximately 29000 hectares of the 33700 hectare Gairloch 
Conservation Unit in Wester Ross, Scotland (Figure 3). The terrain is 
rugged and mountainous, rising to approximately 900 metres altitude in the 
east, and the high rainfall is conductive to bog formation over a substantial 
portion of the area. The aerial photographs used comprised 23cm. format, 
panchromatic black and white prints at a scale of 1:10,000 flown in 
September, 1971 for a N.E.R.C. project. (Figure 4). 
Because a map of habitats - as opposed to vegetation - was the main objective, 
the mapping units included other types in addition to vegetation. It was 
possible to identify 23 image types on the aerial photographs, 11 of which 
(asterisked in Table 2) correspond to McVean and Ratcliffes' Scottish 
Highland Plant Commmities (McVean and Ratcliffe, 1962). Once the habitat 
types, their particular site characteristics, (slope, degree of wetness, 
altitude, etc.) and their corresponding air photo image had been identified 
from field observations and by studying the air photos, it was possible to 
extrapolate to areas not visited in the field, and to confirm or alter 
previously marked boundaries. 
In addition to the habitat types, other features characteristic of the area 
were important for their contribution to the ecological interest of the area 
as a whole. These features, in influencing diversity within and between 
habitats, are described as Inter- and Intra- Habitat Variables and comprise 
categories 24-32 in Table 2. 
Air Photo Interpretation 
  
The reconnaissance nature of the survey and the inacessibility of large 
parts of the study area made the collection of quantitative floristic 
data impossible. It is thought, however, that because of the distinctiveness 
of most of the mapping units and the ability to compare the findings with an 
existing, less detailed map, (Conservation Course, 1971), that mapping 
was accomplished with reasonable accuracy.