132 TROPICAL VEGETATION AND CROPS, MILLER
toration of fertility. The earlier stages of fallow may still show the pattern of cultivation
and so be difficult to separate from the areas actually being cropped. With short-term
crops field checking of photo-interpretation must be carried out in the same season as
that of photography, for fields are seldom permanent and the lay-out will be changed
by the next season. In spite of these complications aerial photographs properly handled
can, as shown by Brunt’s work in the Gambia [3], provide much information about peas-
ant agriculture that could hardly be obtained by any other means.
Shifting agriculture is widely practised in the tropies, and in many places has left
its mark on the natural vegetation in a manner which is clearly shown up on air photos.
The present condition of many tropical areas is much better appreciated after examining
aerial views of shifting cultivation in progress. This system undoubtedly has its merits
where the soils have little permanent fertility and land is plentiful. The latter condition
is disappearing with the growth of popuiations, and before any wise steps can be taken
to secure more intensive use of the land it is necessary to study how far the traditional
forms of agriculture are making use of all the resources of the environment. Aerial
photographs have been of much assistance for that purpose in Africa, and have shown,
for example, how large a proportion of the total land area may be unusable to primitive
cultivators and yet how fully they may exploit the types of land their tools can cope with.
Man’s abuse as well as his use of the land on which he lives may be only too appar-
ent on aerial photographs to those who know the symptoms. These effects are often first
shown by the condition of the vegetation — forest degraded by too frequent clearing for
cultivation, fallow regrowth consisting solely of woody suckers because of destruction of
the top soil, concentrated grazing on termitaries as a result of overstocking, and so on.
In the past the worker in the tropies has often sighed for some record of what conditions
were like before some change of circumstances took place or some new development was
initiated. Even in the short time that aerial photographs have been available for the
tropies they have proved their value as historical documents, and the interpreter of the
future should be well able to judge the wisdom or the folly of the actions which we take
today — which may hardly be a comforting thought.
References.
[1] Aubreville, A. ,Les Foréts Alignés et les Savanes à Termitiéres Buissonan-
tes des Plaines de Winneba et d'Accra (Ghana)", Bois et Foréts des Tropiques,
67, 1959.
[2] Brock, G. C, “Physical Aspects of Air Photography", Longmans, Green & Co.
Ltd., 1952.
[3] Brunt, M, “The Gambia Land Use & Vegetation Survey”, Paper to the Third
Inter-African Soils Conference, Dalaba, 1959.
[4] Cahusae, A. B., “Forest Mapping from Aerial Photographs in Uganda”, Paper
to the Tth British Commonwealth Forestry Conference, 1957.
15] Colwell R. N, “The Future foi Photogrammetry & Photo Interpretation”,
Photogrammetric Engineering, XXV/5, 1959.
6] de Rosayro, R. A, “The Application of Aerial Photography to Stockmapping
and Inventories on an Ecological Basis in Rain Forest in Ceylon”, Empire
Forestry Review, 38 (2), 1959.
[7] Eggeling, W. J., “Observations on the Ecology of Budongo Rain Forest, Ugan-
da", Journal of Ecology, 34 (1), 1947.
[8] Francis, E. C. and Wood, G. H. S, “Classification of Vegetation in North
Borneo from Aerial Photographs”, Malayan Forester, XVIII (1), 1955.
[9] Greenwood, J. E. G. W., *The Development of Vegetation Patterns in Somali-
land Protectorate", Geographical Journal, CXXIII (4), 1957.
