by
J.P. Lanly and J. Clément
The important depletion and degradation of forest cover in tropical zones is having serious effects on the production of forest goods and services and calls more than ever for forest resources monitoring programmes at national, regional and global levels. At national level responsibility rests with the countries themselves, while at regional and global levels specialised international organizations have to take the initiative so that governments and the international community can be made aware of the trends affecting the world's forests. For this reason, at the end of 1978, following the recommendation of the Stockholm Conference, FAO and UNEP undertook a joint programme of forest resources assessment within the framework of the Global Environment Monitoring System (GEMS).
In accordance with its mandate FAO has carried out forest resources assessments at regional and global levels for more than 30 years, publishing the results of its first global survey in 1948. Following this, the 6th FAO Conference (1951) stipulated that this organization should collect and publish information available on the world's forest resources at 5-year intervals. The three versions of the World Forest Inventory were subsequently published for the years 1953, 1958 and 1963, from the compilation of questionnaires filled in by national forestry institutions. For various reasons, related mainly to the diversity of concepts and classifications used by the various countries, the general lack of reliability of the statistics provided and to the fact that these were not always up to date, this approach was replaced by the preparation of regional assessments from documents collected for this purpose. Two of these, entitled “Forest Resources of Africa” by R. Persson (1975)1 and “Forest Resources in the Asia and Far East” (1976), are related to tropical regions. On the occasion of the 4th session of the FAO Committee on Forest Development in the Tropics (1976) an “assessment of the world's tropical forests” was attempted by A. Sommer and published in the double issue no. 112–113 (volume 28) of Unasylva (1976). More recently for the needs of a world timber trend study, FAO undertook a quick reassessment of the situation and likely trends of forest resources of most developing countries (almost all tropical). A part of the results of this study was published in the document “Present and Future Forest and Plantation Areas in the Tropics” by J.P. Lanly and J. Clement (1979).
As far as we know, there do not appear to be systematic studies on tropical forest resources at regional or global levels other than those carried out by FAO. The “Weltforstatlas” published by the Federal Forest Research Institute of Reinbek (F.R.G.) represents an important cartographic work but does not reflect the present situation of the tropical forest cover, as it was published for the most part between 1955 and 1972. Publications of regional and global maps do exist, such as Hueck's phytogeographic map for South America and the maps made under the auspices of Unesco for South America (by the “Institut de la Carte Internationale du Tapis Végétal” - Toulouse) and for Africa South of Sahara (by Professor F. White - Oxford). Global estimates have been attempted here and there, to support theories or opinions on various subjects (deforestation, global carbon budget, energy sources) but these are generally too superficial, being based on insufficient documentation and questionable extrapolations.
The objectives described in the project document signed by FAO and UNEP are the following:
long-term objective: to assist the world community to formulate appropriate measures to avoid the potentially disastrous effects of the trends in the depletion and degradation of tropical forest cover. It relates to programme goals D (Assessment of the critical problems arising from agriculture and land-use) and E (Assessment of the response of terrestrial ecosystems to environmental stress) assigned to the Global Environmental Monitoring System by the 1974 Intergovernmental meeting, for which tropical forest cover monitoring activities have already been initiated by UNEP in cooperation with FAO;
immediate objectives:
to assess, at regional and global levels, the present state of tropical forests and woodlands and the rate and pattern of their depletion and degradation, as a prerequisite for the definition and implementation of the appropriate measures referred to in the long-term objective;
to determine the methodology and the means needed for the continuous updating of this first assessment.
3.1 Preliminary phase
The work started with a preliminary phase for the definition of the methodology and the general programming of the activities during the few months preceding the official starting date of the project (1st December 1978). At the end of 1978 its main methodological features and general planning had been defined. This preparatory phase was made easier thanks to the experience gained during a forest resources assessment study, carried out in 1978 under the responsibility of the project coordinator and already mentioned in section 1. This first study was most useful in many respects:
some principles of classification of natural vegetation and forest plantations had already been defined;
part of the most useful documentation had already been selected and studied;
a first estimate of areas of forests and industrial plantations as well as the order of magnitude of the effects of deforestation and afforestation were already available with an indication of levels of production and productive potential in terms of industrial wood;
the study had allowed the classification of countries with respect to the reliability and completeness of available information on forest resources. This was particularly useful for planning project activities and facilitated the selection of countries where an interpretation of satellite imagery would be needed.
3.2 Working phases
Four main working phases can be singled out for each tropical region, the work for each of which started at three-month intervals in the following chronological order: America, Africa and Asia. The three working programmes have overlapped over almost the whole period of the project which ended in June 1981 with the drafting of the last report.
The study of the 36 tropical African countries was carried out as follows:
data collection phase (January – September 1979) including:
visit to some research institutes in Europe, in particular those specialised in the study and mapping of vegetation;
visit to national institutions in forestry, land use and surveys in Ghana, Ivory Coast and Liberia, three countries particularly affected by the depletion and degradation of forest cover; the mission to Accra also allowed for the collection in the FAO regional office of information concerning various countries of tropical Africa;
selection and ordering of satellite imagery for the interpretation of vegetation cover for Guinea and Angola;
initiation of correspondence with all the African countries concerned, including the mailing of a simple questionnaire and the return by the countries of useful documents on forest resources;
interpretation and compilation phase (October 1979 – November 1980) including:
visual interpretation of satellite imagery of Guinea and Angola;
qualitative and quantitative assessment of the present situation and trends of forest resources, country by country, from all the data collected (as well as the results of satellite imagery interpretation for Guinea and Angola), following a uniform approach using the same concepts and classifications for the 36 countries. This phase of the work ended with the first drafting of a brief for each country;
checking of the first results by the national forestry institutions (November 1980 – January 1981): the above drafts on forest resources were sent to the forestry institutions of the respective countries in order to obtain their comments;
drafting of a final report (February – March 1981) including:
The final version of the 36 country briefs after they had been corrected to reflect the comments obtained (second part of this report);
recapitulation at regional level of all final results;
regional overview (chapter 3 of this first part of the report).
As a whole the work for tropical Africa required 28 months of professional staff distributed as follows:
21 months of the coordinator and forest resources expert;
2 months of the remote sensing consultant;
5 months of consultants (work on some countries and on the regional overview).
