| Summary: | This work aims to show the value and limitations of aerial photographs, Landsat and side-looking airborne radar (SLAB) images for forest-type recognition, tree-species identification, timber-volume estimation and area estimation of the Southeast Asian, the Amazonian and the African tropical forests. The studies comprise an investigation by a review of literature on the applications of the three remote sensing systems in the three tropical forest regions and an experimental investigation of the tropical African forests using Southwestern Nigeria as a typical example. The findings on the technical capabilities of the three systems and the economics of their use were interrelated for the evaluation. The investigations show that remote sensing techniques are easier, quicker and cheaper than ground techniques for tropical forest surveys. Only aerial photography can be successfully used for species identification and volume estimation. Despite the similar cost of SLAR imagery and the cheaper cost of Landsat imagery, they cannot compete successfully with aerial photography for forest-type recognition and area estimation. In combined use, they none-the-less add extra value to photo-information. The lack of funds and the unfavourable weather conditions as well as the complex forest structure and floristic composition are the main factors constraining the use of remote sensing in tropical forest surveys. Options for an economic use of remote sensing are recommended and suggestions for further investigation are made.
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