Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
425 
The use of SPOT simulation data in forestry mapping 
S.J.Dury, W.G.Collins & P.D.Hedges 
Remote Sensing Unit, University of Aston, UK 
ABSTRACT: The composition of a forest is constantly changing, either 
by natural or man-made means. Satellite data may provide a cheaper 
and less time-consuming method of forest inventory and 
map-production compared with more traditional methods. 
The area of study is located within the Forest of Dean, 
Gloucestershire. Numerous digital enchancement techniques are 
applied to SPOT simulation imagery and visually assessed to give the 
best descrimination of the tree types within the forest. A maximum 
likelihood classification is then performed on a suitably enhanced 
image.This proves reasonably successful in distinguishing not only 
different species but also different age classes of certain species. 
A major source of error within the classification results from the 
high spectral variance of urban areas within the forest. Proposed 
methods of overcoming this problem are outlined. 
The digital format of the data facilitates integration into a 
geographical information system, 
be derived in assessing the 
operations. 
1 INTRODUCTION 
This paper describes work investigating the 
potential usefulness of the SPOT satellite 
for providing data of use in forestry 
management. 
One of the most critical problems in 
forestry is the developing shortage of wood. 
Schery (1972) predicted a ten-fold increase 
in timber quantity demand by the year AD 
2000, and even the vast forests of northern 
latitudes and of the tropics will be unable 
to meet these demands. In 1978 the Eighth 
World Forestry Congress stated that; "On 
present knowledge the tropical moist forest 
.... may cease to exist as usable forest in 
40 to 50 years" (Grainger, 1980). 
The problems of shortening supply highlight 
the need for good inventory information. Our 
knowledge of the exact extent of the world's 
forest resources was described by Grainger as 
of cheap, repetitive inventory information: 
to monitor the decline of forested areas, to 
provide accurate estimates of current supply, 
and to monitor the effect of various 
management policies. 
Holmes (1980) argues that a steadily 
increasing proportion of the world's growing 
demand for wood will be provided by 
high-yielding, even-aged plantations. Such 
plantations can increase yields by 8-10 
times the world average of approximately 
lm^/ha; whereas natural forests can be made 
to increase their yield only two or 
threefold, given sufficient inputs of 
capital, manpower and research. Plantations 
can also be developed on land that is 
relatively poor from the point of view of 
agricultural production. This would take the 
pressure off virgin tropical forest to supply 
commercial and non-commercial demands, and 
could ultimately change the world balance in 
favour of the supply side. 
from which further information may 
feasibility and impact of forest 
The Forest of Dean is an example of an 
intensively managed forest. The initial 
objectives of this study were to determine 
precisely what level of detail can be 
attained by interpretation of the SPOT 
simulation data. Previous work (Buchheim et 
al 1984) was unable to achieve discrimination 
to level III - species level - of the 
Anderson System (Anderson et al 1976). This 
study attempted to differentiate species not 
only to species level but for certain species 
to different age-levels. 
2 METHODS AND MATERIALS 
2.1 Study site 
The Forest of Dean is located in 
Gloucestershire. The area administered as 
the Forest of Dean by the Forestry Commission 
is around 11, 900 ha with 9,700 ha under 
productive crops. The Forest is 
characterized by a mosaic of small blocks of 
species and ages of woodland. 
The Forest of Dean was chosen since it 
contains a mixture of both broadleaved and 
coniferous trees, and good ground truth 
already exists in the form of Forestry 
Commission stock maps. The dominant species 
found in the forest are: Oak (Quercus robur), 
Douglas Fir (Pscudotsuga Menziesii), Norway 
Spruce (Picea abies), Corsican Pine (Pinus n 
v maritima), European Larch (Larix decidua), 
Japanese Larch (L Kaempferi), Hybrid Larch (L 
eurolepis), Scots Pine (Pinus Sylvestris) and 
Sweet Chestnut (Castanea sativa).