Reproduced, with permission, from:
Lanly, J. 1982. Tropical forest resources. Food and Agriculture Organization of the United Nations (FAO) paper no. 30. Rome: Food and Agriculture Organization of the United Nations.
In accordance with their mandate and the recommendations of the statutory bodies, FAO and UNEP have undertaken to reassess the present situation and current development of the forest resources throughout the tropical world, within the framework of the Global Environment Monitoring System (GEMS). The FAO/UNEP Tropical Forest Resources Assessment Project, signed on 8 November 1978 by both organizations, started on 1 December 1978 and was completed in June 1981. The findings of this important survey are presented in four technical reports. The first three reports deal with the tropical areas of America, Africa, and Asia respectively; each report consists of a regional synthesis (in Spanish for the Latin American area, in French and English for Africa, and in English for Asia), together with a collection of monographs, country by country, in the official language used for communication between each country and FAO. This fourth report collates all the findings obtained in one overall synthesis for the tropical world.
This survey has consisted essentially of the organization, interpretation, and treatment, country by country, of the vast mass of data collected, within a single simple framework of classifications and concepts. In 13 of the 76 countries surveyed, an interpretation of satellite images has provided a certain amount of additional area data which have been combined with information supplied from other sources. A dialogue has been established between FAO and the forestry departments of the countries concerned, inviting them in particular to look over the first draft of the assessment. In three countries (Peru, India and Burma) the major part of the work has been carried out directly by national institutions of each country.
The following overall data give an initial coverage of the present situation and of the development of tropical forestry resources. The 76 countries surveyed cover a total area of 4 814 million hectares, that is more than 97% of the total area of the countries which for the most part lie in the belt between the tropics or which are subject to a tropical monsoon climate. In 1980 this total area comprised approximately 1 200 million hectares of closed forest (97% broadleaved) and 735 million hectares of open tree formations, which are essentially mixed broadleaved forest - grassland tree formations. To this must be added 410 million hectares of "forest fallow" (that is to say, patchworks of various succession stages of tree formations resulting from clearing by shifting agriculture, including corresponding crop areas) and finally 625 million hectares of shrubland, some altered by agriculture and some not. In 1980, the closed forests which had not yet been touched by logging covered some 990 million hectares overall of which a little less than 675 million hectares of productive forest are untouched, 275 million hectares which are unproductive forests because of stand and terrain characteristics, and finally about 41 million hectares situated inside national parks or equivalent reserves. Approximately 210 million hectares of productive closed forests remain which have been logged over; but only 42 million hectares of this are under intensive management (and more than three quarters of this area within a single country), whilst the rest (that is to say, nearly 170 million hectares) are still in a condition of logged-over forest as yet not subjected to regular management and often destined to be cleared for agricultural use in the near future. About 4.4 million hectares of productive closed forest not hitherto touched (or 0.65% of the total area) are opened up each year to logging; as a rule this process is much more selective in America and in Africa than in Asia, where forests contain a high proportion of marketable timber.
About 7.5 million hectares of closed forest and 3.8 million hectares of open tree formations are cleared each year in order to allow the land to be used for other purposes, usually agricultural. About 45% of such reduction, as far as closed forests are concerned, can be ascribed to shifting cultivation. But to this process of deforestation sensu stricto must be added the numerous kinds of degradation of the woody component of the open tree formations, generally resulting from overexploitation (mainly for fuelwood), overgrazing, and repeated burning. The damage caused by these traditional practices, which are now becoming excessive by reason of population pressure and lack of proper management, either remains constant or is even increasing generally, thus causing a gradual loss of productivity and an irreversible degradation of the other segments of the ecosystems (notably the soil).
The creation of new resources by forest plantation establishment is far from making up for the losses caused by clearing or by the degradation of natural forest ecosystems, both in area and growing stock. At the end of 1980, there were altogether about 11.5 million hectares of industrial and non-industrial plantations in the 76 countries surveyed, and this area is increasing at an annual rate of 1.1 million hectares. Although this rate has greatly accelerated over the last ten years and should continue to increase, the ratio between areas planted and areas of closed or open forests cleared each year remains at 1 to 10.
Obviously all these global figures comprise situations which differ radically from region to region, from country to country, or even from province to province within any one country. Whole sub-regions, such as West Africa and the Indian sub-continent, as well as many mountainous areas, have lost a great deal of their forest cover which is already insufficient to sustain the level of goods and services required for the satisfaction of the needs of the people concerned. On the other hand several other countries and indeed entire sub-regions (such as Central Africa) are for the moment far from reaching this critical point.
This work has been conceived and carried out by the project coordinator, Mr. J.P. Lanly, assisted by the following experts (in alphabetical order): Messrs. S. Andel, J. Clément, P. Coppin, R. Fontaine, M. Gillis, J. Guellec, Y.S. Rao, R.M. Saxena, K.D. Singh and A. van der Zon. The forest resources situation in three tropical countries has been analysed directly by experts from the relevant national organizations: in Peru by Mr. J. Dancé Caballero from the "Departamento de Manejo Forestal" in the University of Molina and by Mr. W. Ojeda Ojeda from the General Bureau of Forests and Wildlife; in India by Messrs. C.L. Bhatia, R.M. Saxena and J.P. Aggarwal from the "Preinvestment Survey of Forest Resources" Institute (Dehra Dun), and in Burma by Mr. Shwe Kyaw of the Burmese Forest Department. The many other experts and institutions which kindly collaborated are hereby most gratefully acknowledged, and their names listed on the following pages.
We regard this study as both timely and useful, as it presents certain essential data on which to base programmes for the conservation, development and wise utilization of tropical forest resources. It is proposed to revise these initial data over the years to come and to bring them up to date, in order to keep governments and the international community correctly informed on the state of tropical forest resources and their evolution at any given time.
M.A. Flores Rodas, Assistant Director-General, Forestry Department
FAO is greatly indebted to the following institutions and persons who contributed to the study:
Bangladesh
- Ministry of Agriculture - Inspector General of Forests
Belize
- Forest Department - Ministry of Trade, Industry, Cooperatives and Consumer Protection
Benin
- Direction des Eaux, Forêts et Chasses (L. Worou)- Projet Pilote de surveillance continue de la couverture forestière tropicale (L. Okio, Kogui)
Bhutan
- Office of the Director of Forests (A.P. Misra)
Bolivia
- Centro de Desarrollo Forestal - Misión Forestal Alemana (R. Stolz)
Brazil
- Instituto Brasileiro de Desenvolvimento Florestal (M. Reis, J.R. Nascimento), Empresa Brasileira de Pesquisa Agropecuaria-Centro de pesquisa Agropecuaria dos Cerrados (L.G. de Azevedo).- Projecto RADAMBRASIL (A.L. Sampaio, H. De Castro, L. Goes, F. Ferreira, M. Pestana y E. de Faria)
- Instituto de Pesquisas Espaciais (Guy, A.P. dos Santos)
- Jaakko Poyry Engenharia (L. Carbonnier, V.I. Suchek)
Brunei
- Office of the Conservator of Forests (Hj Mohd. Yassin B. Ampuan Salleh)
Burma
- Forest Department (Shwe Kyaw, Lin Thaung)
Burundi
- Départment des Eaux et Forêts (A. Kabayanda)
Cameroon
- Direction des Eaux, Forêts et Chasses (B.A. Fultang)- Ecole Nationale Supérieure Agronomique (J.J. Faure)
Colombia
- Instituto de Desarrollo de los Recursos Naturales Renovables (J. Yoria)- Instituto de Colonización y de la Reforma Agraria (T. Mozo); - Proyecto PROMADAM (F. Posada)
- Instituto Geográfico "Agustin Codazzi" - Mapa forestal (A.E. Suarez, G. Hurtado)
- Corporación Nacional de Investigación y Fomento Forestal (A. Delgado)
Congo
- Direction des Eaux, Forêts et des Ressources Naturelles- Centre Technique Forestier Tropical (J.C. Delwaulle, B. Jean)
Dominican Republic
- Dirección General Forestal
El Salvador
- Dirección General de Recursos Naturales Renovables
French Guiana
- Office National des Forêts - Direction régionale- Carte Internationale du Tapis Végétal (F. Blasco, H. Puig)
- Centre d'Etudes de Géographie Tropicale (J.C. Giacottino, J. Koechlin)
Gabon
- Direction Générale des Eaux et Forêts
Ghana
- Forestry Department (J.H. François, K. Kese)- Department of Game and Wildlife (G.A. Punguse)
Guatemala
- Instituto Nacional Forestal
India
- Ministry of Agriculture - Inspector General of forests- Preinvestment Survey of Forest Resources (C.L. Bhatia, J.P. Aggarwal, R.M. Saxena)
Indonesia
- Directorate General of Forestry - Directorate of Forestry Planning/Bina Program (Piran Wiroatmodjo)- Directorate General of Forestry - Directorate of Afforestation and Land Rehabilitation
- Perhum Perhuntani Forest State Corporation (Hartono Wirjodarmodjo)
- BIOTROP/SEAMEO Regional Center for Tropical Biology (Ishemat Soerianegara, Y. Laumonier)
Ivory Coast
- Ministère des Eaux et Forêts (Konan Konan, Lovenbruck)- Société pour le Développement des Plantations Forestières (J. Miélot, N'Gbeche Niango)
- Centre Technique Forestier Tropical (P. Barbaud, H.F. Maitre, (F. Wencelius)
Liberia
- Forestry Development Authority
Madagascar
- Direction Générale du Développement Rural, de la Réforme Agraire et de la Coopérativisation - Service des Eaux et Forêts (Ramanahadra Fils)- Centre National de la Recherche Appliquée au Développement Rural - Département de Recherches Forestières et Piscicoles (A. Rakotomanampison)
Malawi
- Department of Forestry (E.D. May, W.M. Ndovi)
Mexico
- Subsecretaría Forestal y de la Fauna:
- Dirección General de Investigación y Capacitación Forestales- Dirección General del Inventario Nacional Forestal (S.M. Varela, V.E. Sosa)
- Dirección General de Parques Nacionales
- Secretaría de Programación y Presupuesto - Dirección General de Estudios del Territorio Nacional
Nepal
- Department of Forests (P.K. Manadhar, U.B. Shestra) Tribhuwan University - Institute of Sciences
Nicaragua
- Instutito Nicaraguense de Recursos Naturales y del Ambiente
Niger
- Direction des Eaux et Forêts (I. Najada)
Nigeria
- Federal Department of Forestry
Pakistan
- Ministry of Food, Agriculture and Cooperatives - Inspector Genral of Forests/Additional Secretary
Papua New Guinea
- Office of Forests (G.S. Bell)
Peru
- Dirección General Forestal y de Fauna (M. Dourojeanni, L.J. Cueto, W. Ojeda)- Universidad Nacional Agraria - Departamento de Manejo Forestal (J. Malleux, J. Dance)
Philippines
- Bureau of Forestry Development
Senegal
- Direction des Eaux, Forêts et Chasses (El Hadji Sene)
Sierra Leone
- Forestry Division (P.D. Palmer)
Somalia
- National Range Agency - Forest Department
Sri Lanka
- Ministry of Lands and Land Development - Conservator of Forests
Sudan
- Forests Administration (A.A. Bayoumi)
Suriname
- Dienst Slans Bosbeheer (Servicio Forestal)
Tanzania
- Forest Division
Thailand
- Royal Forest Department (Boonchana Klankamsorn, Sathi Chaiyapechara, Swat Nicharat)- Department of Land Development - Land Classification Division (Manu Omakput)
- Department of Public Welfare - Division of Land Settlements (Vichit Piyarom)
- Kaestsart University - School of Forestry (Sathit Wacharakitti-Prasan Pradistapongs)
- National Research Council - Thailand Remote Sensing Program (Suvit Vilbusreth)
- Committee for Coordination of Invetigations of the Lower Mekong Basin (J. Ceruse)
Togo
- Office National de Développement et'Exploitation des Ressources Forestières (O. Nadiombe)
Upper Volta
- Direction de l'Aménagement Forestier et du Reboisement (B.S. Ouedraogo)
Zaìre
- Service Permanent d'Inventaire et d'Aménagement Forestier (Kanu Mbisi, Mabiala-ma-Khete, C. Noël)
Zambia
- Forest Department (G.E. Grout)
In addition to the authors mentioned in the foreword the following FAO forestry experts assisted in the collection and compilation of the data and in the revision of the country briefs: P.E.T. Allen (Nigeria), M. de Backer (Upper-Volta), J.B. Ball (Nigeria), W. Beattie (Brazil), E. Bourguignon (Benin), G. Borgo (Nicaragua), A. Cameratti (Upper-Volta), M.H. Cárdenas (Costa Rica), C. Chandrasekharan (different countries from tropical Asia), P. Coppin (Bolivia), J.G. Devitt (Burma), R.G. Dixon (Indonesia), L.E. Dow (Liberia), D. Dun (Malaysia), A. Fearnside (Nepal), R. Fenton (Malaysia), W. Guerra (Mexico), H. Haufe (different countries from tropical America), T. Hounto-Hotegbe (Burundi), I. Hutchinson (Malaysia, Paraguay), J.P. Huygen (Gambia, Senegal), J.K. Jackson (Thailand), E. Jones (different countries from tropical America), J.D. Keita (Ghana, Mali), B. Kingston (Indonesia), R. Levingston (revision of the English text), M.J. Lyons (Ethiopia), J. Malleux-Orjeda (Mozambique), A.D. Mather (Kenya), W.L. Mittak (Guatemala), M. Muñoz Alaba (Honduras), D.O. Nelson (Nepal), E. Pelinck (Nepal), M. Sachtler (Bolivia), J.M. Samyn (Upper-Volta), D.C. Schwaar (Sierra Leone), G.M. Schmidt (Liberia), H. Schrewe (Belize), H. Sutter (Nigeria), H. Tasaico (Bolivia and Paraguay), K. Watanabe (Nepal), and F. Zamarriego (El Salvador).
1. BACKGROUND
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 does 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 extrapolation. It is worth noting, however, that a recent study by N. Myers entitled "Conversion of Tropical Moist Forests" published in 1980 by the National Academy of Science of the United States is the first, to our knowledge, to review the problem of deforestation in 48 tropical countries. But this document is mainly concerned with moist forests and does not make a systematic quantitative assessment of their present situation.
Each of the three recent less "hasty" studies on the forest resources in the tropics, i.e. those of Sommer, Lanly and Clement, and Myers, do not cover the subject in full. The first and the third are only concerned with moist forests (the first of them at the regional and sub-regional levels), while the second, although it analyzes the situation on a country by country basis, mainly focuses on natural woody formations and plantations producing timber for industry. The present project consists of detailed analysis, country by country, of the situation and trends of all natural and planted woody formations, and should, therefore, fill in the more important gaps in the preceding studies and create a sufficiently solid basis of uniform data which can then be updated and improved continuously. One would hope, therefore, that the data herein will serve in the future as points of reference in the many debates and reports on the regression and degradation of tropical forests and make it possible to put an end to confusion and misunderstandings that have surrounded this subject up to now.
2. OBJECTIVES OF THE STUDY
The objectives described in the project document (drawn up in English) signed by FAO and UNEP are the following:
- long-term objectives: to assist the world community to formulate appropriate measures to avoid the potentially disastrous effects of 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. Tropical forest cover monitoring activities have already been initiated by UNEP in cooperation with FAO;- immediate objectives:
(a) to assess, at regional and global levels, the present state of closed 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 objectives;(b) to determine the methodology and the means needed for the continuous updating of this first assessment.
The first short-term objective has been achieved through a detailed analysis, country by country, the methodology of which is described in chapter II. The study covers completely the 75 larger countries of tropical America, Africa and Asia, to which has been added Papua New Guinea that is generally included under Oceania. Each of these three regions has been the subject of a separate technical report, consisting of two sections, i.e. a regional summary in the main language or languages of communication most widely used (Spanish for tropical America, English and French for tropical Africa and English for tropical Asia), and a collection of summaries, country by country, describing in more detail the situation and evolution of forest resources at the national level (written in the country's official language of communication with FAO). To the three regional reports there is added a summary on the situation of forestry resources for the tropical world as a whole and this is given in chapter III of this report.
Conclusions on the follow-up of this study and the main results are summarized in chapter IV. There are two appendices, one giving a sketch for the possible computerization of the results and the other gives a list of the statistical and cartographic syntheses that exist at both the regional and global levels.
3. PROJECT ACTIVITIES
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 study on forest resources of developing countries, carried out in 1978 under the responsibility of the coordinator of this project 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 changes to the same (deforestation and afforestation) were already available along with an indication of levels of production and productive potential in terms of industrial wood;
- this 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
(a) Four main working phases can be singled out for each of the three tropical regions, 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 July 1981 with the drafting of this final report.
(i) Data collection phase, including the following activities:
- visits to some research institutes in Europe, in particular those specialized in the study and mapping of vegetation;- visits to national forestry, landuse and survey institutions in some of the major forestry countries in each region, as well as to the regional offices of FAO;
- selection and ordering of satellite imagery for the interpretation of the vegetation cover for the 13 countries for which the information collected was either clearly insufficient or else contradictory (6 entire countries in tropical America, 2 entire countries in tropical Africa and 5 countries in tropical Asia including two in their entirety);
- initiation of correspondence with the forestry services of nearly all the 76 countries concerned plus a certain number of smaller countries or territories (the islands and archipelagos of Oceania in particular, which in the end have not been included in this study because of lack of means). This correspondence began with a request to the forestry institutions to transmit recent information and documentation on a certain number of points, in particular: the current situation and evolution of areas with natural woody formations and forestry plantations, the growing stock by forest type and the different forms of forest exploitation. This information and documentation were then classified with those coming from other sources (particularly numerous FAO reports and satellite imagery) for interpretation by project personnel. More than half the 76 countries replied by sending in data and documentation;
- drafting of contracts in the case of the three countries (Burma, India and Peru) where a national forestry institute had been put in direct charge of the work following the same methodology and the same norms as those established for all the other countries concerned.
(ii) Interpretation and compilation phase for the information collected, including the following:
- visual interpretation of satellite imagery on the countries selected for this, in order to correct the area estimates by broad categories of vegetation and land use;- qualitative and quantitative assessment (by project personnel) of the present situation and trends of forest resources, country by country, from all the data collected (as well as the results of the interpretation of the satellite imagery) following a uniform approach and using the same concepts and classifications for the 73 countries being studied (the 76 countries less those three which were the subject of a contract). This phase of the work concluded with the first draft of a brief for each country;
- the execution of the three contracts for Burma, India and Peru. The final reports of these studies were presented under the form of briefs for each country similar to those drawn up for the 73 countries directly studied by the project personnel.
(iii) Checking of the first results by the national forestry institutions: the first drafts of the briefs on forest resources were sent to the forestry institutions of the respective countries in order to obtain their comments.
(iv) Drafting of the final reports for the three regions (technical reports 1, 2 and 3), each of which includes:
- the final version of the country briefs reflecting the comments obtained (second part of each of the three regional reports);- recapitulation at regional level of all final results;
- regional synthesis (chapter III of the first part of each of the three regional reports).
(b) For the three regions as a whole, the present synthesis report was prepared to summarize the overall results and to give indications on the possible follow-up of the study and the computerization of the results.
(c) In total, the entire study, which took place over a period of about 32 months (December 1978/July 1981) required 83 months of work by professional staff (i.e. about 7 man/years) distributed as follows:
1. INTRODUCTION
A fundamental precept in the formulation of the methodology for this study has been that qualitative and quantitative information on tropical forest resources and their evolution exist and that they are abundant, scattered and extremely diverse. Each of these qualifications requires consideration. The first one may appear paradoxical. In fact all those who would like to have available a comprehensive and coherent collection of information on the current situation and trends in tropical forest resources complain, quite rightly, that such a comprehensive collection does not exist. It is true that the great mass of existing information has not been interpreted and "organized" at the national level in many tropical countries. Even when national syntheses do not exist, it is not possible to regroup them together because the classifications and the concepts used differ from one country to another. So, overall and regional assessments are both very imprecise and not very uniform.
In an era where speed is of the essence, people who use information are in a hurry and they either do not take, or else they have not got, the time needed to collect and interpret the mass of information available. In their defense it should be said that this work of much less stimulating than the work involved in juggling with models and other intellectual games...that, unfortunately, very often involve the use of doubtful data. We can also say in their defense that for some time now the world's press has taken up the problem of the reduction and degradation of tropical forests and some confusion has developed particularly as regards the concepts and the entities in discussion. Are we talking of tropical countries or developing countries? Of closed tropical forests or of all tropical tree and/or shrub formations? Are we talking only of moist tropical forests or of all tropical forests? When we speak of the depletion in the tropical forests, are we talking about a reduction of forest areas or only of a reduction in the growing stock through logging, which (is it necessary to repeat?) is an integral part of forest management and development. There has been a lot of debate in recent years on the problems of tropical forest resources without, however, there being any attempt to organize the existing information nor to introduce some clarity in the concepts being utilized.
The main reason why these data are difficult to obtain relates to the second aspect mentioned above, that is to say, their dispersion. There are data not only in national and international forestry organizations but also in many small and large organizations such as survey institutes (and remote sensing centers), agricultural statistics services, colonization and land use institutes, universities and research organizations in the countries concerned or in developed countries (research studies and academic theses), consulting firms, etc. In this respect it is worth mentioning in particular the many thematic mapping studies carried out at regional, national and provincial levels which multiplied during the seventies thanks to the use of remote sensing techniques (Landsat satellite and side-looking airborne radar imagery, very small scale aerial photographs). In the framework of this project, a certain number of institutions were visited and discussions and correspondence took place with many specialists. It has not been possible, of course, to visit or contact the very large number of national institutions which could have been in a position to provide some useful information, in order to resolve contradictions in the available data, and correct erroneous interpretations found in the documents. It is important, however, to underline the fact that a large part of the project activities consisted in collecting as much as possible of the relevant data scattered around the world.
A third characteristic of this mass of data is its diversity when seen from at least three different angles:
- with regard to the subject matter, which is often not restricted to forestry alone: data concerning deforestation are mainly of a socio-economic character (e.g. distribution and growth of the agricultural population, types and patterns of cultivation, internal population migrations, fiscal and other incentives for forest clearing, colonization programmes, development of infrastructures and improvement of accessibility, etc.). Phytogeographic and ecological information and maps are also of essential importance to classify forests according to their production potential. Laws and regulations in the field of nature conservation indicate the forest areas unproductive for legal reasons, etc.;- with regard to the level or scale of information: it is easier to bring to light forest resource data when forest inventories, reconnaissance surveys and maps have been carried out at a national or sub-national level. A large amount of information, however, can be found in studies at lower levels (provinces, districts, investment areas, watersheds). Although, in many cases, a simple quantitative extrapolation is not feasible, these data are always useful to check corresponding information at national level, to compare situations from one country to another or, at least, provide examples to illustrate particular situations and issues (deforestation, degradation, survival and success of plantations, etc.). These local studies are the most numerous and contain the largest amount of useful information. However, it is very often difficult to obtain these local studies because they have been published in a very small number of copies and are not quoted in most bibliographies (university theses, for instance, or because they are not known to foresters since they do not deal with forestry matters (e.g. studies in sociology, population, agriculture, etc.);
- lastly, with regard to the reliability and accuracy of data: all documents on forest resources are obviously of different value and there are many crude assessments and dangerous extrapolations which must be considered with caution. It is not unusual for documents to take up obsolete information that has never been updated thus disregarding changes which have occurred in the meantime. It is of the most importance to detect these deficiencies in the data through checks against other sources.
This study has consisted mainly in the selection, organization, interpretation and processing of this dispersed, abundant and heterogeneous information using a single framework of classifications and concepts for the 76 tropical countries studied (see section 2). However, in certain countries, reliable base-line data on the areas of woody vegetation which could have been used for subsequent up-dating, did not exist at the national level. In other countries the project was confronted with two or more sets of area information which could not be matched. In these cases it was decided to interpret available satellite imagery (for the years 1972 to 1978) to check and possibly correct basic data on areas obtained in a first phase (see section 3). For all countries, it has been necessary to update the information at the end of 1980 on the basis of trends observed in recent years and to forecast the situation at the end of 1985 by projecting these trends over a period of five years (see section 4).
2. CONCEPTS AND CLASSIFICATIONS
The value and usefulness of any forest resources assessment study depends, to a large part, on the concepts and classifications used. In the framework of this study these will not only have to have certain general characteristics, (conform with the objectives of the study, be adapted to the type of items surveyed, be defined with precision and without ambiguity, be matched as closely as possible to the needs of the most important users), but they must also satisfy the following particular conditions:
- be compatible with the concepts and classifications already in use in the tropical world, particularly with those in the FAO World Forest Inventory reports for purposes of comparison and consistency;- apply uniformly to the three main tropical regions in order to obtain a coherent picture for the tropical world overall.
An attempt has been made to meet all these conditions by adopting the simple forest concepts and classifications presented and discussed in the following paragraphs.
2.1 Concepts and classification of natural woody vegetation
2.1.1 A large number of systems of tropical vegetation classification already exist, using various criteria (ecological, physiognomic, physiographic and others) established at national and regional levels. In this latter category, we can single out the following classifications for each of the three tropical regions:
- tropical America:
- the Unesco classification ("International Classification and Mapping of Vegetation" in the collection "Ecology and conservation" - No. 6 - 1973) used for the "Vegetation Map of South America" at 1/5 000 000 scale prepared by the "Institut de la carte internationale du tapis végétal" (Toulouse, France); this classification utilizes criteria that are both ecological and physiognomic;- the phytogeographic classification of K. Hueck, used for the map "Mapa de la vegetación de America del Sur" at 1/8 000 000 scale (in "Los bosques de Sudamérica - Ecología, composición e importancia económica" - 1978);
- the ecological classification of L.R. Holdridge into "Life zones" which has been applied to several countries in Central and South America;
- tropical Africa:
- the so-called Yangambi classification, elaborated during a meeting of experts on phytogeography organized in 1956 under the sponsorship of the Commission for Technical Cooperation in Africa South of the Sahara: the agreement reached on the definition of African vegetation types allowed for the preparation of the "Vegetation Map of Africa South of the Tropic of Cancer" at 1/10 000 000 scale published on behalf of l'"Association pour l'Etude Taxonomique de la Flore d'Afrique Tropicale" with the assistance of Unesco;- the classification designed by Prof. F. White for a second version of this latter map, prepared for Unesco and which should be published in 1981;
- tropical Asia:
- the classification by Champion of the forest vegetation of the Indian sub-continent described in "A Preliminary Survey of the Forest Types of India and Burma" (1935) and revised in "A Revised Survey of the Forest Types of India" by H.G. Champion and S.K. Seth (1968);- the classification by C.G.G.J. van Steenis in his "Vegetation Map of Malaysia" at 1/5 000 000 scale covering Malaysia, Indonesia, the Philippines and Papua-New Guinea, published in 1958 with the collaboration of Unesco;
- the classification of the main forest formations in the tropical Far East by T.C. Whitmore in his book "Tropical Rain Forests of the Far East" (1975).
To these regional classifications we should also add classifications at the world level by J. Schmithüsen in his "Atlas zur Biogeographie" (1976).
Vegetation classifications at national level are many and they have been used in this study for the evaluation of forestry resources in those countries where there was a corresponding map. As mentioned already in chapter I, the interpretation of the last ten years of satellite and radar images has led to a new generation of vegetation maps with their own classifications. The criteria and categories of the classifications are very different not only from country to country but even within the same country.
2.1.2 It was finally decided to ensure compatibility between the classification used in this project and that of Unesco because of the latter's useful characteristics which are as follows:
- it applies to the whole world while the majority of others only apply to one region;- it is probably the first collective and international attempt at a global vegetation classification (while each of the others has been elaborated by a single specialist or a national institute);
- it contains a certain number of most important distinctions for forest resources management, such as: separation between tree and shrub formations, separation between more or less closed tree formations on the one hand and grasslands with a tree synusia on the other. This latter distinction is essential in tropical countries since mixed forest-grassland formations, unlike closed forests, play a most important role in grazing and are more prone to fires.
2.1.3 In addition to the distinctions mentioned above (tree/shrub and closed forest/mixed forest-grassland formation), there are other essential classification criteria for woody vegetation areas, both from the productive and environmental viewpoints, such as:
- distinction between predominantly broadleaved forests and predominantly coniferous forests;- separation between forests that have not been disturbed recently (virgin or primary) and "manipulated" forests: forests clearfelled and later on provisionally abandoned by shifting cultivation ("forest fallow"), forest degraded by overgrazing and fire, logged over forests;
- distinction between productive and unproductive forests using the criterion of production of wood for industry, and separation of unproductive forests into those which are unproductive for physical reasons and those which are so for legal reasons (national parks, integral reserves, biosphere reserves etc.).
The simultaneous application of all these criteria entails a large number of classes. Some of these classes are not important or else cannot be identified from interpreted documents and images and, in the latter case, the corresponding areas and characteristics cannot be estimated. The classification which has been finally adopted is limited to the most useful categories.
The following diagram shows the classification used and the corresponding criteria. The classification and the different criteria finally retained are described in detail herein below.
2.1.4 Classification of natural woody vegetation (N/n)
The only vegetation types which are considered are those for which woody elements cover more than 10% of the ground. Though it is often difficult if not impossible to estimate this percentage from the descriptions and this percentage is not always used in the classifications, it has been selected as the limit between the types in which the woody elements constitute actually a community and those where they are scattered or (in lines) in landscapes with a non-woody vegetation or without any other vegetation.
The word "woody" is used although the trees of some monocotyledons do not contain "wood" in the usual meaning of the word.
The adjective "natural" is used only in relation with plantations which can be considered as a purely artificial vegetation (see below section 2.2). It is not synonymous of "primary" and does not mean at all that there is no human or, more generally, biotic interference. On the contrary, a significant proportion varying with countries of "natural vegetation" corresponds indeed to degradation stages (after fires, clearings by shifting cultivation, overexploitation for wood, grazing) or reconstitution stages after degradation, or to forests disturbed by logging, with or without management.
- N stands for any vegetation type of which the dominant woody element is the tree. The definition of a tree is the one given by the book "Terminology of Forest Science, Technology, Practice and Products", viz. "a woody perennial plant typically large and with a single well defined stem carrying a more or less definite crown" (height more than 7 metres for mature trees).
- n corresponds to any vegetation type the main woody elements of which are shrubs of more than 50 cm and less than 7 metres high [2].
- NH corresponds to types with predominance of trees of broadleaved species (angiosperms) dicotyledons or monocotyledons (e.g. palms, raphias). Predominance is characterised by a proportion of more than 50% of the crown cover.
- NS corresponds to types with predominance of trees of coniferous species (gymnosperms Coniferous species for instance of genus Podocarpus are often present in mixed tropical forests of medium and high mountains, without being predominant. As a result no significant forest area has been classified as NS in some countries in spite of the occurrence of coniferous species.
- NHC stands for closed broadleaved forests, i.e. those which, when not recently cleared by shifting agriculture or heavily exploited, cover with their various storeys and undergrowth, a high proportion of the ground and do not have a continuous dense grass layer allowing grazing and spreading of fires. They are often, but not always, multistoreyed. They may be evergreen, semi-deciduous or deciduous, wet, moist or dry.
- NHB stands for bamboo formations.
- NHc/NHO corresponds to mixed broadleaved forest-grassland tree formations with a continuous dense grass layer in which the tree synusia cover more than 10% (e.g. various forms of "cerrado" and "chaco" in America, tree and wooded savannas and woodlands in Africa). This division between closed forests and mixed formations is more of ecological than physiognomic type and is not characterized necessarily by a crown cover percentage, since, for instance, trees of some woodlands cover the ground completely like closed forests.
A similar distinction has not been introduced for predominantly coniferous forests (NS) since it has not the same ecological importance and is difficult, if not impossible, to use.
- NHCf (or NSf) corresponds to stands of closed broadleaved forest (or coniferous forest) which have not been cleared (for agriculture mainly) in a recent past (i.e. during the last 20 to 30 years). These forests are either managed or unmanaged forests, primary or in an advanced stage of reconstitution after having been cleared at least 60 to 80 years ago (old secondary forests) or secondary (but of more than 20 to 30 years). These forests may have been logged-over once or more times, having kept their characteristics of forest stands, possibly with modified structure and composition through in particular impoverishment in timber species (logging is accounted for in a subdivision of this category - see below).
- NHCa (or NSa), or "forest fallow", stands for all complexes of woody vegetation deriving from the clearing by shifting cultivation of closed broadleaved forests (or coniferous forests) and constituted by a mosaic of various reconstitution facies ("secondary bush", "young secondary forests", stands of Musanga or Cecropia, "secondary growth"). Patches of uncleared forest and of agricultural fields are generally included in those areas as it is impossible to account for them separately within the shifting cultivation areas (in particular in the visual interpretation of satellite imagery). When site conditions are unfavourable (e.g. broken terrain) or when the fallow period is reduced to a very short period, clearing by agriculture leads to such a degradation of the site that the reconstitution of the forest is not possible within a foreseeable future; the resulting degraded vegetation is not included in the NHCa (or NSa) category but in shrub formations (n) or outside woody vegetation.
- NHCfl (or NSfl) are "productive" closed broadleaved forests (or coniferous forests), managed or not: their characteristics, those of the terrain and the present regulations allow (or might allow) for the production of wood for industry (sawlogs and veneerlogs pulpwood, pitprops and other industrial poles). Their distance to consumption or export centres is not taken into account, i.e. this category may include economically inaccessible forests.
- NHCf2 (or NSf2) include "unproductive" closed broadleaved forests (or coniferous forests). They are subdivided in:
- NHCf2i (or NSf2i) which are unproductive for physical reasons, i.e.:
- those which cannot produce wood for industry because of their characteristics (forests with stunted and crooked trees, or made of monocotyledon species such as palm or raphia stands);- those which are inoperable because of terrain conditions (terrain too rough or permanently inundated);
- NHCf2r (or NSf2r) which are unproductive for legal reasons, i.e. in which logging is prohibited by law or other regulations (e.g. national parks, integral reserves, biosphere reserves etc.).
When forests belong to both categories NHCf2i (or NSf2i) and NHCf2r (or NSf2r) at the same time, their areas are accounted for only in the latter one.
- Whenever possible, similar divisions are made within the mixed broadleaved forest grassland formations category, between productive (NHc/NHOl) and unproductive types (NHc/NHO2) and, within the latter category, between those (NHc/NHO2i) which are unproductive for physical reasons (stand and terrain characteristics) and those (NHc/NHO2r) which are unproductive for legal reasons (e.g. included in national parks). 40% of forest cover can be considered as an indicative limit between productive mixed broadleaved tree formations (NHc/NHOl) and those that are unproductive because of stand characteristics (part of NHc/NHO2i). This limit is used in the Unesco classification to separate "woodlands" or "open stands of trees" from grasslands with tree synusia.
- Mixed broadleaved forest - grassland formations in the various reconstitution stages after clearing by agriculture are indicated by the symbol (NHc/NHOa). Areas indicated for this category, when their estimation has been possible, include also agricultural fields and patches of untouched formations (as for NHCa category) because of difficulty in separating them from the rest of the secondary vegetation.
- NHCf1m (or NSf1m) are productive closed broadleaved forests (or coniferous forests) intensively managed. The concept of intensive management is used here in a restricted way and implies not only the strict and controlled application of harvesting regulations but also silvicultural treatments and protection against fires and diseases. These forests constitute the part of the permanent productive forest estate in a given country to which the concept of "annual allowable cut" can be meaningfully applied.
- NHCf1u (or NSf1u) stands for the productive closed broadleaved forests (or coniferous forests) other than those intensively managed. They are separated in two groups:
- NHCf1uv (or NSf1uv) are the unmanaged productive closed broadleaved forests (or coniferous forests) undisturbed (or "virgin"), i.e. primary forests or old secondary forests where there has been no logging for the last 60 to 80 years;- NHCf1uc (or NSf1uc) are those which have been logged-over once or more times during the last 60 to 80 years (the very large majority of the remaining ones have been exploited in fact in the last 30 years or so).
- n stands for vegetation types, the main woody elements of which are shrubs (thickets, shrub savannas). In most cases no subdivision has been introduced within these categories for lack of precise information. This category includes shrub formations which have been altered by agriculture.
A summarized definition of the various classes with their corresponding symbols, as used in the presentation of results, is given below (in the order they appear in the tables of area statistics):
- NHCf1uv: undisturbed productive closed broadleaved forests not (intensively) managed;
- NHCf1uc: logged-over productive closed broadleaved forests not (intensively) managed;
- NHCf1u : productive closed broadleaved forests not (intensively) managed;
- NHCf1m : (intensively) managed productive closed broadleaved forests;
- NHCf1 : productive closed broadleaved forests;
- NHCf2i : closed broadleaved forests unproductive for physical reasons (stand and terrain characteristics);
- NHCf2r : closed broadleaved forests unproductive for legal reasons;
- NHCf2 : unproductive closed broadleaved forests;
- NHCf : closed broadleaved forests;
- NHCa : forest fallow (of closed broadleaved forests).
- Equivalent categories of coniferous, bamboo and closed forest have similar symbols in which NHC is replaced by NS, NHB and N respectively.
- NHc/NHO1: productive mixed broadleaved forest-grassland tree formations;
- NHc/NHO2i: mixed broadleaved forest-grassland tree formations unproductive for physical reasons (stand and terrain characteristics);
- NHc/NHO2r: mixed broadleaved forest-grassland tree formations unproductive for legal reasons;
NHc/NHO2: unproductive mixed broadleaved forest-grassland tree formations;
- NHc/NHO: mixed broadleaved forest-grassland tree formations;
- NHc/NHOa: forest fallow (of mixed broadleaved forest-grassland tree formations);
- n: (essentially) shrub formations.
2.1.5 Discussion
As the above classification is very simplified for the purposes of this study at the world level, it obviously only gives a schematic outline of the situation as regards woody vegetation cover. Likewise the transfer from one category to another of this classification reproduce rather summarily the processes of progressive evolution ("savannization" of closed forests, degradation of open tree formations, by overexploitation and overgrazing, into shrub formations, or into formations where the woody cover is below 10%, etc.). To these simplifying effects inherent in all classifications, we also have to add a certain number of difficulties that are briefly analyzed below.
- The difficulty has already been noted of appreciating the minimum percentage of 10% woody cover by using the descriptions that were submitted. This level of cover is used in the Unesco classification and also in those of the forest vegetation and land use of many temperate and tropical countries, and as one of the density limits in the 1963 edition of the FAO World Forest Inventory. Its adoption, therefore, is not in dispute but it is also true that one cannot be sure that the estimates of areas given in this study for open tree formations (NHc/NHO) and some shrub formations (n) conform exactly and uniformly in all countries.
- The distinction between tree formations (N) and shrub formations (n) is not always easy. In particular, many open formations are made up of a mosaic of stands where trees or shrub elements may predominate and the division of their area between tree and shrub formations can only be approximate. Many vegetation maps frequently use the undifferentiated concept "tree and shrub savannas". Due to the fact that there are in general some shrub elements in tree formations, and, on the contrary, few, if any, tree elements in shrub formations, the denomination of shrub formations is completed with the adverb "essentially": (essentially) shrub formations.
- The distinction between formations with a predominance of trees of broadleaved species (NH) and those with a predominance of trees of coniferous species (NS) is, in general, easier to make although there are some transition stands where it may be difficult to distribute areas. It should be noted, however, that there are small coniferous stands in certain broadleaved formations that in general have not been accounted for separately. This is the case, for example, of the patches of Agathis in Kalimantan (Indonesia).
- The same holds true for the separation of bamboo stands. Sometimes these form the undergrowth for stands whose dominant trees are broadleaved and which have, therefore, been classified as broadleaved formations. When, however, they represent the basic element of the stands - some of them, as is the case in India, are managed as such - they have been classified in the category NHB. To the difficulty of separating these two forms of bamboo occurrence, there are some added problems, i.e. :
- the almost total absence of data on bamboo stands in tropical America, probably because they are less utilized in this region as compared to Africa, and Asia in particular. This has made it impossible to assess the areas of these formations for America, in spite of the fact that it is known that stands of significant size exist in certain zones (e.g. in the provinces of Caldas and Valle in Colombia and the coastal zone of Ecuador). Their total area, which is probably quite small for tropical America as a whole, is likely included for the most part in that for closed broadleaved forests (NHC);- the fact that bamboo often constitutes the new growth after clearing for shifting cultivation in certain areas (e.g. Viet Nam): in these cases there has been some confusion between bamboo formations (NHB) and broadleaved forest fallow (NHCa) without there being any possibility to indicate the sign and size of the error involved;
- finally, the uncertainty on productivity and past logging of bamboo stands because of the lack of precise information on the subject. The distribution of formations into "productive" and "unproductive" and between undisturbed productive formations and logged over formations can therefore only be approximate in most cases (except for some countries such as India).
- The distinction, that is fundamental on ecological and management grounds, between closed broadleaved forests (NHC) and mixed tree forest-grassland formations (NHc/NHO) is generally easy to establish mainly because it is taken into account in maps and inventories. It sometimes happens, however, that the "savannization" process, in certain particular climatic conditions, causes the occurrence of forest formations that are in transition between closed dry forests and woodlands ("foret claire") or wooded savannas. This is what is happening, for example, in Guinea Bissau and it has led the authors of the recent vegetation map for this country to make a distinction between "semi-dry" forests with a discontinued grass layer (classified in this study under NHC) and "dry" forests with a continuous grass layer similar to woodlands ("foret claire") (and thus classified under NHc/NHO).
- It should not be necessary to insist on the importance of carefully distinguishing "forest fallow" (NHCa, NHBa, NSa and NHc/NHOa) in relation to forests unaltered by agriculture (NHCf, NHBf, NSf and NHc/NHO) on the one hand, and, on the other hand, in relation to permanent agriculture and other forms of land use. Although forest fallows are very variable quality depending on the length of the fallow period, and the characteristics of the soil and the terrain, they represent an important land reserve which could be used for some forms of agro-sylviculture management. In any case they have an important conservation role to play because of their woody cover. It sometimes happens, however, that because of the lack of sufficient information a certain confusion develops between closed broadleaved forest fallow (NHCa) and broadleaved shrub formations (nH), or again between the forest fallow of open tree formations (NHc/NHOa), unproductive open tree formations (NHc/NHO2i) and broadleaved shrub formations (nH). This last difficulty is particularly true in some African countries where the extreme overlapping of human activities, particularly grazing and agriculture, has meant that degraded open woodland formations that have long been abandoned by agriculture have been assimilated as the forest fallow of these same formations.
- The distinction between closed forests that are unproductive for physical reasons (NHCf2i, NHBf2i, NSf2i) and productive closed forests is generally not too difficult although one cannot always be sure that the limiting characteristics of stand and terrain that distinguish them are precisely the same for all countries. On the other hand, the estimate of forest areas that are unproductive for legal reasons (NHCf2r, NHBf2r, NSf2r, NHc/NHO2r), - i.e. mainly those forests inside national parks and equivalent reserves - is in most cases approximate, although the orders of magnitude have been respected. In fact, even though it is usually true that one can have good qualitative descriptions of the vegetation cover of each park and reserve, the area of the corresponding formations is rarely given with precision.
2.2 Classification of plantations (P)
2.2.1 The term "plantation" corresponds to:[3]
- forest stands established artificially by afforestation on land which previously did not carry forest;- forest stands established artificially by reforestation on land which carried out forest within the previous 50 years or within living memory and involving the replacement of the previous crop by a new and essentially different crop.
Plantations in the sense used in this study do not include stands established by artificial regeneration and essentially similar to those they are replacing. These artificially regenerated forests are part of productive closed broadleaved (or coniferous) forests (intensively) managed (NHCf1m/NSf1m).
A distinction is made between industrial plantations (P..1) established totally or partly for production of wood for industry (sawlogs and veneer logs, pulpwood, pitprops mainly) and non-industrial plantations (or "other plantations") (P..2) established mainly for one or several of the following objectives:
- production of fuelwood and wood for charcoal (possibly as industrial energy source);- production of small wood for domestic consumption (in particular rural populations);
- non-wood products (fruits from forest trees, palm hearts, gum arabic, cinnamon etc.);
- soil protection.
Those tree plantations which are usually outside the competence of foresters are not accounted for. This is the case in particular of plantations of rubber trees, palm oil trees, coconut trees, and of the shade tree plantations for agriculture.
A distinction is made between plantations of broadleaved species, or hardwood plantations (PH.1/PH.2), and plantations of coniferous species, or softwood plantations (PS.1/PS.2).
Hardwood plantations are divided between plantations of fast-growing species (PHH1/PHH2) and plantations with other broadleaved species (PHL1/PHL2). Limit between these two groups of species corresponds approximately to a gross mean annual increment of 12-15 m[3]/ha/year. However, separation is made above all on the basis of the species. For instance Eucalyptus and Gmelina plantations are classified as fast-growing species (PHH1/PHH2), whereas teak plantations are included in the PHL1/PHL2 categories.
The categories of plantations are finally the following:
- PHL1: industrial plantations of hardwood species other than fast-growing ones;PHH1: industrial plantations of fast-growing hardwood species;
PH.1: industrial hardwood plantations;
PS.1.: industrial softwood plantations;
P..1: industrial plantations.
- PHL2: non-industrial plantations of hardwood species other than fast-growing ones;
PHH2: non-industrial plantations of fast-growing hardwood species;
PH.2: non-industrial hardwood plantations;
PS.2: non-industrial softwood plantations;
P..2: non-industrial plantations.
- PHL=PHL1 + PHL2: plantations of hardwood species other than fast-growing ones;
PHH=PHH1 + PHH2: plantations of fast-growing hardwood species;
PH=PH.1 + PH.2 : hardwood plantations;
PS=PS.1 + PS.2 : softwood plantations; all plantations.
P=P..1 + P..2 : all plantations.
2.2.2 Discussion
- The separation of plantations from natural forests did not pose any particular problems in most countries. In fact, there are very few doubtful examples. But doubt can arise, for example, regarding enrichment planting (in lines or "layons", in strips, in plots) where the species introduced can become predominant and eclipse the initial population. However, these works, done in a few countries, only cover a very small area which, in general, has been included or merely mentioned under the category of intensively managed forests (NHCf1m/NSf1m, and possibly NHc/NHO1m). There are also cases where the plantations of one species replace a stand that was originally mixed, where nevertheless this species is, if not dominant, at least present to a significant extent. The most important case is that of teak plantations in Java which have replaced mixed teak forests and which have eventually been classified as plantations. In all the other cases of plantations on cleared forests, the previous stand has been replaced by a homogeneous population of a single exotic species or of a species present in another part of the country, or else again by a species belonging to the original forest but which was present only at a very low density.
- Generally speaking, artificial stands planted in block, covering a minimum area, let us say over 0.5 ha, have been considered as plantations. However, some non-industrial plantations, that generally serve to supply rural populations with firewood or wood for domestic uses, or plantations along roads and canals are laid out in the form of hedge rows or lines of one or several rows of trees. Wherever possible, as for example in Bolivia and in Pakistan, these plantations have been taken into account by, generally, using the factors for converting lengths into areas that are currently used in the respective countries. In this connection we should also mention certain soil protection plantations that appear under the form of rows forming grids around unplanted zones, in which the percentage of forest cover created can be in the order of 10 to 30%, and which have been accounted for as non-industrial plantations.
- As mentioned in paragraph 2.2.1, those tree plantations that are generally outside the control of foresters have not been included. In some countries fruit tree plantations have been realized by the forestry services. This is the case, for example, in Brazil where tax incentives also apply to plantations of fruit trees such as Psidium guayana, Paullinia cupana and Bertholletia excelsa and the palm trees Euterpe spp.. Cashew nut plantations (Anacardium occidentale) are established by the forestry services of certain African countries and these have been taken into consideration as non-industrial plantations in this study. Since these populations are itemized separately in the country briefs included in technical reports 1, 2 and 3, the reader can, if he so wishes, subtract the corresponding areas.
- The distinction between industrial and non-industrial plantations has not usually posed any serious problem, as the main objective of the plantations was usually specified unambiguously in the documentation consulted. If the products of the final cut are destined for industrial processing (including, for example, creosoting telephone poles to preserve them) the plantations have been classified as industrial, regardless of what the thinnings are used for. An exception to this rule is the plantations whose main purpose is soil protection (particularly the rehabilitation of mountain zones and the protection of catchment areas) which have been classified as non-industrial plantations without considering what might be the final destination of the products from the final cuts.
- The separation into fast-growing hardwood species (PHH) and the other hardwood species (PHL) has been made, as mentioned before, on the basis of their gross mean annual increment. In general the latter makes it possible to systematically classify a given species in the same category regardless of which tropical country is concerned. However, the more difficult ecological conditions in certain areas may mean that sometimes a fastgrowing hardwood species will be classified in the second category. It is for this reason that the eucalypt plantations of some Sahelian countries have been classified as hardwood plantations other than fast-growing whereas in most other countries eucalypts are considered as fast-growing species.
2.3 Concepts of volume
2.3.1 Three volume concepts (either mean volume per ha or total for a given forest category) are used throughout this study for closed broadleaved forests and coniferous forests (NHCf-NSf) and for productive mixed forest-grassland tree formations (NHc/NHO1), which are:
- VOB: gross volume over bark of free bole (from stump or buttresses to crown point or first main branch) of all living trees more than 10 cm diameter at breast height (or above buttresses if these are higher);- VAC: (for forests not intensively managed): volume actually commercialized, that is volume under bark of logs actually extracted from the forest;
- AAC: (for forests intensively managed): gross annual allowable cut, in general equated with current annual yield.
2.3.2 Discussion
- The VOB concept of gross volume has been adopted in preference to others as it is the one most widely used in forest inventories, and is therefore the one for which the least corrections are necessary in order to arrive at an average estimate of gross growing stock for each category of forest formations in a given country. inventories which do not use this concept of volume, ratios have been applied to their results, determined on the basis of inventories of similar forest formations. Other concepts of gross volume such as that of stem wood above 7 cm diameter ("bois fort") or concepts of biomass have not been used since in the case of tropical forests there are far fewer estimates concerning these than there are figures relating to the concept of volume VOB that has been selected.
- The volume actually commercialized (VAC) corresponds to the commercial production of sawlogs and veneer logs actually extracted from productive forests logged without intensive management (NHC-NSf1u and NHc/NHO1u) in the current conditions of the timber market in each of the countries in the study. It is lower, sometimes considerably lower, (particularly in tropical America and Africa), than the potential commercializable volume. The total VAC that exists in productive forests not yet exploited (NHC-NSf1uv and NHc/NHO1uv) in a given country corresponds to available existing "reserves" assuming that logging is to continue in the same conditions. These estimates are obviously just indicative since for many countries the output per ha tends to increase, (utilization of a larger number of species, better recovery, salvage logging before clearing for agriculture, etc.), or, on the contrary, to diminish (elimination of certain species through the increase in the cost of transport consequent to the available forests becoming distant from the centres of consumption and export, absence of certain commercial species in the forests not yet logged, etc.).
- For productive forests with intensive management (NHC-NSf1m and NHc/NHO1m) another concept of volume has been applied, which is that of the gross annual allowable cut (mainly the volume of sawlogs and veneer logs of marketable species) which does not have any real meaning for unmanaged forests where the production is not regulated at a given level. We should be careful to distinguish this concept from that of mean annual increment of stands which, in general, is applied to the total growing stock; (all diameters and species together) which is significantly higher.
3. INTERPRETATION OF SATELLITE IMAGERY (LANDSAT)
3.1 The lack of recent and consistent data at national level on the areas of forest formations in 13 countries prompted to decide on the interpretation of Landsat imagery for these countries. These 13 countries are: Costa Rica, El Salvador, Guatemala, Honduras, The Dominican Republic and Paraguay in America; Angola and Guinea in Africa; and Burma, India, Kampuchea, Lao and Viet Nam in Asia. The main purpose of the work of satellite imagery interpretation was the checking and possible correction of estimates derived from a previous attempt to update maps and other available documents. Because of the global nature of this study, of the extent of the categories used and, in certain cases, of the impossibility of collecting detailed ground truth data, the work was limited to the visual interpretation of images, or more precisely, of the 1/1 000 000 scale positive transparencies of bands 5 and 7 and of the standard colour composite from bands 4, 5 and 7. The interpretation work benefited from the experience acquired by the FAO Forestry Department within the framework of the FAO/UNEP Pilot Project on Tropical Forest Cover Monitoring carried out in three countries of West Africa (Benin, Cameroun and Togo). The remote sensing consultant (J. Guellec) in charge of interpretation work for the 8 countries of America and Africa and for 3 out of the 5 countries in Asia, had participated in this pilot project.
The selected scenes were all images from Landsat 1 and 2, from 1972 to 1978 with cloud cover less than 10% above the territories of the countries concerned. The selection of images was made with the assistance of the FAO Remote Sensing Unit using the microfilms of band 5 for checking the quality of each scene and the location and distribution of clouds.
For each country documents which could assist in the interpretation as "ground truth," such as vegetation maps and forest inventory reports were used, as well as the 1/1 000 000 scale aeronautical charts, particularly for the transfer of international boundaries on to the images.
In the case of Angola, the size of the country (more than one million km[2]) and the limited time available meant that only half the images of acceptable quality could be studied with only every second frame being selected on each orbit. For three other countries (India, Kampuchea and Lao) the work of interpretation was limited to only a portion of their territory.
This global project does not aim at drawing forest maps but mainly at assessing the present situation and evolution of tropical forest resources qualitatively and quantitatively. Moreover, the delineation of the various types of vegetation from satellite images is not necessary since estimation of areas can be obtained on a statistical basis through the identification of vegetation types in each dot of a grid. For this reason, the latter device has been preferred for estimating the area of each interpretation class except in the case of India and Burma where mapping was carried out. A systematic dot grid on transparent stable material, with a 5 mm by 5 mm spacing in the directions parallel to the sides of the image, was applied on the transparencies observed on a mirror stereoscope. Band 5 or band 7 was usually visualized simultaneously with the colour composite on the stereoscope. The dot grid was limited to the effective part of the images, taking into account an average lateral overlap of 20% in the tropical regions[4] and an overlap of 10% in the North-South direction. Before the interpretation itself, some important features were indicated on one transparency of each scene, such as international boundaries, rivers, important roads in order to facilitate orientation.
This method was adopted after having compared its results on an experimental basis with those of a more complete procedure including the delineation of vegetation classes and the subsequent use of a dot grid for area estimation. Differences for each class, such as closed forests, open forests, degraded forests, were not systematic and did not exceed 4% when these types were in the form of large patches. Differences were high and systematic for classes represented by scattered patches of small dimensions. In this latter case, the smallest patches are not delineated and the total area of the corresponding classes is underestimated, while the estimation by interpretation of dots is not biased in this respect. Another advantage of the statistical method is to allow for a reduction of the personal bias of the interpreter in the delineation of classes, more particularly in the transition zones where the drawing of the limits is often somewhat subjective.
The interpretation key is compatible with the general classification used in this project (see paragraph 2.1.3). The following distinctions have been introduced:
- broadleaved forests/coniferous forests;- closed forests/mixed forest-grassland formations;
- closed forests not altered by agriculture/closed forests altered by agriculture ("forest fallow").
Mangroves and large areas of swamp formations were also identified. Other distinctions, such as between open tree formations and open shrub formations or between productive and unproductive forests, or between undisturbed forests and logged-over forests were not possible through the visual interpretation of satellite imagery and the corresponding area estimates were obtained through an analysis of other documentation and phytogeographic, vegetation or land use maps.
In total 208 scenes corresponding to an overall area of around 295 million ha were interpreted, which is about 6% of the total area of the countries studied.
The list of images used and the location of their centres, as well as comments on their interpretation are given in the country briefs for the 7 corresponding countries of Africa and Asia (technical reports 2 and 3). For what regards the 6 countries of tropical America general overall comments and the location of the centres of the images studied are given in the first part (regional synthesis) of technical report 1.
3.2 Use has also been made in this study of the results of the interpretation of remote sensing data (radar images, satellite images, very small scale aerial photographs) carried out in recent years for vegetation mapping at the national level in a number of countries in the three regions, that is to say:
- tropical America (6) : Bolivia, Brazil, Colombia, Haiti, Mexico and Peru;- tropical Africa (9) : Benin, Cameroon, Guinea Bissau, Mozambique, Nigeria, Senegal, Sierra Leone, Togo and Upper Volta;
- tropical Asia (3) : Indonesia, The Philippines and Thailand.
Results from the interpretation of data obtained from recent remote sensing techniques have thus been utilized in 31 of the countries studied; for 13 of these the interpretation was done directly by this project, while for the 18 others use was made of the results of interpretation carried out by others. Twelve of these countries are in tropical America, 11 in tropical Africa and 8 in tropical Asia.
4. ESTIMATION PROCEDURES
4.1 General principles
In this study, estimates have always proceeded from the smaller geographic area to the wider area, in other words, from a part of the country or from an entire country to a group of countries (sub-region), then to the whole of each of the three regions, then to the whole of the 76 tropical countries studied. This procedure from the "bottom to the top" has been faithfully respected throughout the study and in no case have overall estimates at the level of a group of countries (for deforestation, for example) been broken down further to the level of the countries. The latter, or sub-divisions of the same, have been the study units whose results have subsequently been added up for the subregions, the regions and the whole tropical area studied.
As already indicated in section 1, use has been made for each country of a considerable amount of information and documentation of diverse origins and types that have been analyzed and selected beforehand. A list of what are considered the most important references is given in the bibliography attached to each country brief in the second parts of technical reports 1, 2 and 3. Although the overall approach and the estimation principles have been applied in a uniform manner for all countries, the variable relative importance, depending on countries, of the type of information and documentation available has led to some adaptation of the estimation procedures. Thus, for example, the assessment of areas for categories of natural woody vegetation has obviously been done a different way in the 13 countries where an interpretation of satellite imagery was carried out by the project, as compared to what was done in the 63 other countries.
- All the data collected have been organized and interpreted so as to be inserted in the simple uniform framework of classifications and concepts described in section 2 above. The processing of the raw information was, therefore, as objective and logical as possible. Such treatment was made necessary by the fact that from one country to another, and very often inside the same country, the concepts and classes did not cover similar entities, even when the same words were used. Without this processing the compilation of the raw data at the sub-regional, regional and world levels would have given results that would have been basically incorrect; a fault found in those forest resources surveys based solely and simply on the analysis of questionnaires that had been filled out and returned. The term "forest" for example does not imply the same formations in moist tropical countries as it does in countries where conditions are arid and more precautions than one would think are often necessary in order to eliminate all of the effects of such different (albeit natural) viewpoints[5].
- It is important to distinguish between two types of estimates: on the one hand, those which refer to the situation and evolution of forest resources until 1980 and derive from the interpretation and processing of data corresponding to this period and, on the other hand, projections up to 1985 which reflect, for each country, what has seemed to be the most likely situation at this date, account being taken of present trends - including potentialities and constraints - in the political, social and economic fields.
- From the outset relations were established with the national forestry institutions so as to have these associated as closely as possible with this study. These institutions subsequently received the first drafts of the country briefs so that they could provide comments and corrections. Forty-five countries (out of the 76) have, at one or several stages of the study, collaborated with the project, which made it possible, in particular, to resolve differences of appreciation that had emerged on such and such an aspect. Although it does not represent the official views of the countries - if only for the fact that the concepts and classifications used by this project are not necessarily those that each country employs - the results, in their final form, have been either explicitly or tacitly ratified by the countries concerned.
- The validity of the estimates naturally varies according to the countries and the items concerned. The deductions, projections and approximations made have a degree of security that is a function of the numerous criteria, particularly, of course, the quantity and quality of the raw data that has been treated. It would have been possible, for example, to give each of the many estimates an index of validity which would, however, have been subjective and somewhat arbitrary. It has been considered preferable to describe succinctly, in the country briefs, the way that the more important estimates have been arrived at each time, with an indication of the corresponding sources. When certain estimates derive from an overall judgment, more than from a coherent deduction, this has been duly pointed out in the corresponding country brief. These estimates are usually indicated in parentheses in the tables of the country briefs.
- The accuracy of the results could not be quantified, but in each case it is in a more or less direct proportion with the value of the estimated item and could be expressed within a certain range of percentages of this (for example from +/- 5% to +/- 25%). Moreover, approximations are inevitable and it is advisable to round out the estimates in a way that will be in relation to their accuracy. This means, for example, that one should round off to 10 000 ha or even 50 000 ha the areas of natural woody formations for large countries, while for the smaller countries they should be rounded off to the best level of accuracy decided upon, in this case a thousand hectares. In the summary tables for subregions and regions, the totals shown are to the best level of accuracy adopted, since the results obtained by adding up the estimates of small and large countries together have been kept just as they are. The best levels of accuracy adopted are as follows:
- areas for categories of natural woody formations: 1000 ha- areas for plantation categories: 100 ha
- annual rates of deforestation by category: 100 ha
- VOB/VAC volumes per ha: m[3]
- total VOB/VAC volumes: 0.1 million m[3] (100 000 m[3])
- gross annual allowable cut (AAC) per ha: 0.05 m[3]
- total gross annual allowable cut (AAC):0.01 million m[3] (10 000 m[3])
4.2 Particular estimates
4.2.1 Areas of categories of natural woody formations
The systematic approach taken has been to establish a base of area estimates at a date as recent as possible and to subsequently update this base in order to bring these estimates up to the end of 1980 and then project them to the end of 1985. The base date selected is generally that of an inventory, a reconnaissance or a vegetation map at the national level, or, more accurately, that of the aerial photography coverage or remote sensing images on the basis of which these works have been done. The updating and the projections are made by taking into account the various changes that the natural woody vegetation has been subject to, especially that due to man (clearing and alienation of the forest for other land use, logging, management, reservation, degradation by overgrazing, excessive cuts - particularly for firewood -, "savannization" by firing, etc.) and the corresponding transfer from category to category. The more usual direct transfers are indicated in the figure shown below for broadleaved formations (NHC-NHc/ NHO-nH), with the abbreviation of the type of modification incurred:
am. : introduction of intensive management;
def. : deforestation by clearing an alienation for other uses;
deg. : degradation;
exp. : logging (mainly for sawlogs and veneer logs);
ref.() : natural reforestation (the sign "(
)" between parentheses indicates that the areas of the corresponding transfers are small);
res. : legal reservation (classification as national park or equivalent reserve);
sav. : "savannization: (of closed forests as a result of firing).
Other similar tables can be drawn up for coniferous formations (NS) and those of bamboo (NHB). It is reasonable to suppose that there are no significant transfers from the above table of broadleaved formations to the corresponding table of coniferous formations. On the other hand there is a transfer between these two tables and that for the bamboo formations, but they are very difficult to perceive.
The more important transfers, from all points of view, come from deforestation - transfers from the categories NHCf-NSf-NHBf to categories NHCa-NSa-NHBa, n and "non-woody", and from NHc/NHO1 and NHc/NHO2 to NHc/NHOa, n and "non-woody" -, and from logging - mainly transfers from NHC-NHB-NSfluv (undisturbed closed forests) to NHC-NHB-NSfluc (logged closed forests). At the level of each country, agricultural statistics, (particularly the trend over time in the numbers of families by types of crop), and information on agricultural cultural practices, (average cropping and fallow periods in shifting cultivation, average size, type of clearing, etc.) provide valuable assistance in quantifying, at the national and sub-national level[6], the trends in land use. During the course of the study of a country, the general breakdown of land between the different forms of occupation is reconstituted at each stage (reference date, end-1980 and 1985) so as to show up any possible contradiction with the conclusions arrived at from agricultural population and production statistics.
The transfer of areas from category to category corresponding to degradation process (and no longer to deforestation) are obviously more difficult to quantify. This is because there is much less precise information on the subject (practically none at the national level) and because these are gradual changes that are difficult and somewhat artificial to translate by transfers from category to category. This is the case, for example, of the evolution of productive closed forests (NHC-NS-NHBf1) into unproductive closed forests (for reasons related to the characteristics of the stands: part of NHC-NS-NHBf2i), which is particularly noticeable in many coniferous forests that are over-exploited and over-grazed, or the evolution of productive open tree formations (NHc/NHO1) into unproductive open tree formations (for reasons related to the characteristics of the stands: part of NHc/NHO2i) or even in shrub formations (n). Other degradation transfers are those that correspond to the "savannization" of closed forests (from NHCf to NHc/NHO). In all those cases where transfers concern areas of some size, their estimation has been done so as to translate as completely as possible these gradual regressive evolutionary processes within the framework of the classification used.
The area estimates of a given category at the end of 1980 and at the end of 1985 differ from each other by the sum of the transfers towards this category from other categories. The preceding table shows, for example, that unmanaged logged-over productive closed broadleaved forests (NHC/NHO) will increase by the amount of unmanaged undisturbed productive, closed broadleaved forests logged during this period but will be reduced by the areas either deforested (becoming NHCa or "other"), or reserved for national parks (NHCf2r), or degraded (into NHCf2i) or managed (NHCf1m) or again being "savannized" (NHc/NHO1 and NHc/NHO2i). In many cases the reduction or increase in area of a forest category between 1980 and 1985 is the result of many, and not just one, processes of evolution. Apart from the example mentioned previously, it is worth mentioning that of the reduction of undisturbed closed broadleaved forests without intensive management (NHCf1uv) which is the sum of the transfers (all of them negative), brought about by logging, management, degradation, reservation, deforestation and "savannization" as the preceding table shows. At least two factors for reducing undisturbed forests intervene in nearly all cases, and these are logging and deforestation, but the nature and extent of their effects on the forest environment are quite different. The former, that is usually very selective, leaves behind a forest that is impoverished but not destroyed and which can be intensively managed, provided, of course, it does not immediately become the prey of clearing operations. The latter, on the other hand, i.e. deforestation, means that the forest disappears for a certain time, or for ever, and makes it practically impossible to have a sustained yield of forest products.
4.2.2 Areas of plantations
Generally speaking it has been possible to get gross estimates of areas for plantations up until the end of 1978. For 1979 and 1980, as well as for forecasts up to 1985, the gross figures can be deduced from programmes currently under way and those that are likely to be implemented.
To go from gross figures to net figures, i.e. to the areas of successful plantations, that are "reasonably stocked", success/survival rates have been applied that vary according to each country in relation to the types of plantations (industrial plantations, plantations for firewood, soil protection, etc.), their age, the organizations responsible (forestry services, private companies, village communities), the species planted, the sites, etc. Sometimes the gross and net figures have both been provided in the country briefs so as to allow for comparative evaluations. However, only the net figures have been used in the summary tables in the regional syntheses.
In the country briefs the distribution of areas by age class, (from 5 to 5 years up to 20 years of age and from 10 to 10 years from 20 to 40 years of age) has been given each time the information available made the estimation possible, even in a very approximative way. In the latter case the areas by age classes are indicated in parentheses. In some rare cases of non-industrial plantations, only the total area of existing plantations could be given since the information found in the documents did not make it possible to arrive at even a rough breakdown by age class.
In the case of plantations which have already coppiced one or several times, or in cases of replanting of species that do not coppice after logging, the areas have been systematically distributed in function of the age of the first generation and not that of the subsequent generation or generations. Replantings with the same category of species do not, therefore, appear in the age class corresponding to their date, but in that of the first logged plantations that they replace. The main reason for this is that there is little information on the exact date of the logging of plantations and that the rotations given for each species are generally only of an indicative value. In certain cases, however, an indication has also been given for what could be the distribution by age class of new generations by assuming average rotations for each species or category of species.
4.2.3 Volumes and increments
The estimate of total volumes is derived systematically from those of the corresponding average volumes per hectare through the application to the latter of areas determined at each reference date (end 1980 and end 1985). Overall estimates of volume have never been produced independently from the surface areas supplied by the study.
Estimates of volumes per hectare are determined from the results of forest inventory reports. In the country briefs the more important estimates that have been found are reported in order to justify the averages finally selected. Apart from the problems arising from the diversity of concepts of volume in forest inventories already mentioned in paragraph 2.3.2, two other difficulties have had to be overcome, that is to say:
- the lack of recent forest inventories at the national level in the great majority of tropical countries. Almost all the evaluations of volume concern limited areas and it has thus been necessary to construct weighted estimates (particularly by type of forest) applicable overall to each large sub-division (or forest category) of the country or directly to the country as a whole;- the different mensuration methods,(all other things being equal, particularly for the same concept of volume), applied in forest inventories depending on the country, (and sometimes even inside the same country), introduce distortions into the estimates which have to be corrected in order to get results that are as consistent as possible. Nevertheless, it was impossible to avoid some anomalies in the study which it would be advisable to remove when complementary information becomes available. As an example of this state of affairs, we can mention the considerable difference between the gross volumes per hectare of undisturbed productive closed broadleaved forests (NHCf1uv) of French Guyana on the one hand and Suriname and Guyana on the other, which is certainly due, in large part, to the estimation methods used.
When there was a lack of information on the gross volume (VOB) per hectare of logged-over productive closed broadleaved forests (NHCf1uc), this has generally been taken as equal to that of the corresponding undisturbed closed broadleaved forests (NHCf1uv), less twice the net volume extracted from the forest (VAC) (i.e. approximately the gross volume of trees felled), by assuming, as a first estimate, a compensation between natural growth of the stand after logging (positive factor) and the damage caused during logging: broken trees, roads, etc. (negative factor). When managed forests exist in a given country their gross standing volume per hectare and that of unmanaged logged-over forests of the same type have generally been taken as equal to each other.
The data on gross volumes (VOB) per hectare of forests that are unproductive for physical reasons (stand and terrain condition) are far fewer than data relating to productive formations since forest inventories are mainly concerned with these latter. The estimates that have been made should be generally considered as very approximate and as not having the same validity as those concerning productive formations.
The gross volumes (VOB) per hectare and in total have been estimated overall for broadleaved forests (NHCf) and coniferous forests (NSf) as well as for productive open tree formations (NHc/NHO1). No attempt has been made to estimate the average and total volumes of secondary formations of forest fallow (NHCa, NSa, NHc/NHOa) because of the great variety of corresponding categories and the lack of data on their volume. For the same reasons, the volumes of unproductive open tree formations (NHc/NHO2) and shrub formations (n) have not been estimated.
The estimate of standing "volumes actually commercialized" (VAC) has only been done for undisturbed productive closed forests (NHCf1uv, NSf1uv) (volume exploitable in the present circumstances contained in these forests). In certain countries it was necessary to distinguish between the usual selective logging and "salvage logging" of forests before their being cleared for other uses. A difficulty arose in the case where selective logging is done in several passes in a reduced period of time, that is less in any case than the theoretical rotation indicated in a polycyclic system (in the order of 25 to 40 years). The approach taken in this case has generally been to consider that the VAC was equal to the sum of the repeated cuts (examples in Sabah, Sarawak and the Philippines).
Logged-over forests (NHCf1uc, NSf1uc) also contain volumes of exploitable timber and, in fact, some forests are "creamed" twice or more. Nevertheless it is very difficult, if not impossible, to estimate the average commercial volume which remains in forests that have already been logged over and no corresponding figure has been given except in a few cases.
In many countries it has been estimated that there would be an evolution in the average VAC from the period 1976-80 and to 1981-85, generally towards a slight increase mainly to allow for the greater number of species that can be marketed.
Information exists in the documentation relating to certain countries in tropical Asia for what regards the weight of dry matter in bamboo stands. This information has been gathered and used in the total estimates for each of these countries, which have not been summarized at the regional level.
Data found on volume increment in natural forests either before or after logging have been given in the country briefs. Because of the variety of formations, the different succession stages in the evolution towards climax formations and the relatively small amount of information that has been found, no attempt has been made to provide averages at the national level which would have been too general and too approximate. On the other hand, in the case of intensively managed forests, data exist, that are generally acceptable, on the gross annual allowable cut (AAC) which have been used to deduce the total allowable cut of these stands at the level of each country concerned. It is worth remembering in this connection that intensively managed closed forests, as understood in this study, represent barely 4.75% of productive closed forests as a whole.
5. PRESENTATION OF RESULTS
In the study results are presented at three different levels:
- at the level of each of the 76 countries studied, each of which is the subject of a "country brief", except for Zimbabwe and with 3 briefs for Malaysia: Peninsular Malaysia, Sabah, Sarawak. Thus there is a total of 77 briefs: the group of country briefs corresponding to a given tropical region make up the second part of each of the three regional reports (technical reports 1, 2 and 3 for tropical America, Africa and tropical Asia respectively). For a certain number of countries results are given by geographic or phytogeographic divisions;- at the level of each of the three tropical regions (grouping together a total of 14 sub-regions) the country results are summarized and their presentation has been the subject of a regional synthesis making up the first part (or, to be precise, chapter III of this first part) of each of the three regional reports;
- at the level of the 76 countries overall, results by region are regrouped and set forth in a concise way under chapter III of the present report.
5.1 Countries studied
Tropical America (23)
The 23 countries studied for tropical America are:
- all the countries of South America, including the French department of Guyana, except for three countries in the Southern cone (Argentina, Chili and Uruguay) that are mainly of a temperate or sub-temperate climate (10 countries or territories in all);- Mexico and all the countries of Central America (8 in all);
- the largest island countries in the tropical sector of the Caribbean (except for Puerto Rico); 5 countries in all.
The recapitulation of results at the regional level has been made according to the sub-regional framework:
- Central America (7) and Mexico : Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama.- CARICOM (4) : Belize, Guyana, Jamaica, Trinidad and Tobago.
- Other Caribbean (5) : Cuba, Dominican Republic, French Guiana, Haiti, Suriname.
- Tropical South Latin America (7) : Bolivia, Brazil, Colombia, Ecuador, Paraguay, Peru, Venezuela.
Tropical Africa (37)
The 37 countries studied in tropical Africa are all the tropical countries of continental Africa, with the exception of Djibouti and Mauritania, plus Madagascar. The Mediterranean countries of North Africa (Morocco, Algeria, Tunisia, Libya, Egypt) and the temperate countries of Southern Africa (Republic of South Africa, Lesotho, Swaziland) have not been covered by the study.
The countries have been classified into the following five sub-regions:
- Northern Savanna Regions (6) : Chad, The Gambia, Mali, Niger, Senegal, Upper Volta;- West Africa (9) Benin, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Nigeria, Sierra Leone, Togo;
- Central Africa (7) Angola, Cameroon, Central African Republic, Congo, Equatorial Guinea, Gabon, Zaire;
- East Africa and Madagascar (13) Burundi, Ethiopia, Kenya, Madagascar, Malawi, Mozambique, Rwanda, Somalia, Sudan, Tanzania, Uganda, Zambia, Zimbabwe;
- Tropical South Africa (2) : Botswana, Namibia.
Tropical Asia (16)
The 16 countries studied are all the countries south of China, from Pakistan in the west to the Indonesian part of the island of New Guinea in the east, with the exception the Maldive islands and Singapore, to which has been added Papua New Guinea which is normally considered as a country in Oceania. More than half of all these countries are situated within the tropics, except for Bhutan, Nepal and Pakistan, which are entirely to the north of the Tropic of Cancer. These last three countries have, however, been included since they form part of the Indian sub-continent and are in part under the tropical and sub-tropical influences which are felt to a significant extent to the north of the tropic.
These 16 countries have been divided into sub-regions as follows:
- South Asia (6) : Bangladesh, Bhutan, India, Nepal, Pakistan, Sri Lanka;- Continental Southeast Asia (2) : Burma, Thailand.
- Insular Southeast Asia (4): Brunei, Indonesia, Malaysia, The Philippines;
- Centrally planned tropical Asia (3) : Kampuchea, Lao, Viet Nam;
- (Oceania) : Papua New Guinea.
5.2 Country briefs
5.2.1 Text
The plan is the same for all the country briefs. The present situation as regard forest resources and the present trends are described in two separate sections, each of them consisting of one section on natural woody vegetation and the other on plantations.
The description of the composition and the physiognomy of the different types of natural woody vegetation (paragraph 1.1.1) is followed by an estimate of areas for natural woody vegetation up to the end of 1980 and information on ownership, legal status, management, and forest utilization (paragraph 1.1.2). The interpretation of the available results of forest inventories makes it possible to estimate the volume of stands at the national level up to the end of 1980 (paragraph 1.1.3).
The comments on plantations begin with an introduction (paragraph 1.2.1) and this is mainly concerned with historical aspects, followed by an estimate of the areas of forest plantations at the end of 1980, with separate sections on industrial plantations and non-industrial plantations, by categories of species and age classes (paragraph 1.2.2). Quantitative data on the characteristics of the plantations, particularly on mean annual increments, are given in paragraph 1.2.3.
In section 2.1 concerning present trends for natural woody vegetation, a distinction has been made between deforestation in the strict sense (paragraph 2.1.1), i.e. essentially the alienation of forest areas for agricultural purposes (permanent or shifting) or for other uses, and between degradation of woody formations, particularly mixed forest-grassland tree formations, resulting from other factors, such as fire, over-grazing, over-exploitation for firewood and charcoal, etc. (paragraph 2.1.2). By taking into account the trends as regards forest utilization (paragraph 2.1.3), projections are made regarding areas and volume of stands for the end of 1985 (paragraph 2.1.4).
Finally, in section 2.2, indications are given on the programmes for forest plantations and the probable extent of their realization for the years 1981 to 1985, which makes it possible to forecast planted areas by category of species up until the end of 1985.
A bibliography at the end of the brief for each country shows the main documents upon which the estimate of forest resources and the trends were based. Since the reference dates are particularly important in this study, these are shown in chronological order.
5.2.2 Tables
As well as tables concerning some secondary aspects, each country brief has a set of basic tables that illustrate the text and which are described here below:
- "Areas of natural woody vegetation estimated at end 1980" (paragraph 1.1.2)
This table gives the areas (to the nearest thousand ha) of categories of natural woody vegetation according to the classifications shown in section 2.1 above. The table is followed by notes and explanations to explain how the estimates were arrived at.
- "Growing stock estimated at end 1980" (paragraph 1.1.3)
Based on the area estimates of the preceding table, and the averages per hectare of gross volume over bark (VOB) and "volumes actually commercialized" (VAC) (given to the nearest m[3]), it has been possible to arrive at the corresponding total volumes for closed broadleaved forest formations, for coniferous formations and for productive open tree formations (NHc/NHO1). The gross annual allowable cuts (AAC), either per hectare or in totals, are also given for the existing categories of intensively managed forests.
- "Areas of established plantations estimated at end 1980" (paragraph 1.2.2)
Areas that have been successfully planted up until the end of 1980 are indicated, in thousands of hectares (generally to the nearest 100 ha) by species, or categories of species, and by age classes, respectively for industrial and non-industrial plantations and for plantations as a whole. It should be remembered that these estimates correspond to net areas, i.e. those obtained after reductions have been made to take into account the degree of success achieved in the programmes, the replanting of unsuccessful plantations or those that have already been exploited and the failure of others. In some cases mention has also been made of raw data found in the documents studied for purposes of comparison.
- "Average annual deforestation" (paragraph 2.1.1)
This table gives the areas of closed forests cleared each year during the past 5 years (1976-80) and the corresponding projections for the coming five years. As already mentioned, the concept of deforestation that has been used implies the clear cutting of forests for use other than forestry (principally agriculture) and their eventual replacement, after a few years, by secondary vegetation.
A logged-over forest that is not subsequently replaced by agriculture, changes in forest category (from NHCf1uv or NSf1uv to NHCf1uc or NSf1uc) but is not deforested in the sense used in this study, even if the volume logged is relatively high. These transfers of virgin forest to logged-over forest are not reflected in this table. In order to know the surface area of primary forest covered annually by clearing and by forest logging, the area of virgin forest newly logged each year should usually be added to the figure on deforestation indicated in this table.
Indications are also given in the text of paragraph 2.1.1 on the transfer of closed forest (NHCf or NSf) to forest fallow (NHCa or NSa) in the case of shifting agriculture, in terrain which allows for reconstitution of the soils after a period of cropping.
The destruction of open woodland formations (NHc/NHO) and shrub formations (n) are also indicated in this paragraph as are the transfers within the NHc/NHO category and those to the n category.
- "Areas of natural woody vegetation estimated at end 1985" - "Growing stock estimated at end 1985" (paragraph 2.1.4)
These tables are similar to those in paragraph 1.1.2 and 1.1.3. They provide estimates of corresponding areas of volumes as these have been projected on the basis of estimates of deforestation in the next five years and other assessments related to conservation and utilization of forests in the period 1981-85.
- "Areas of established plantations estimated at end 1985" (section 2.2)
These tables are similar to those in paragraph 1.2.2 and integrate the projections of established plantation areas during the period 1981-85 on the basis of existing or planned programmes and the financial and other constraints of each country.
5.3 Results at the regional level
The presentation of results at the regional level, which is given in chapter III of the first part of each of the three regional reports, follows the same outline as that for the country briefs. In the tables the countries are shown in line and are grouped into the sub-regions indicated in paragraph 5.1. The summary tables given are the following:
- Table 1a Areas of natural woody vegetation estimated at end 1980 Closed broadleaved forests (NHC)- Table 1b Areas of natural woody vegetation estimated at end 1980 Coniferous forests (NS)
- Table 1c Areas of natural woody vegetation estimated at end 1980 Bamboo forests (NHB)
- Table 1d Areas of natural woody vegetation estimated at end 1980 Closed broadleaved, coniferous and bamboo forests (N.f)
- Table 1e Areas of natural woody vegetation estimated at end 1980 Open broadleaved forests (NHc/NHO)
- Table 1f - Areas of natural woody vegetation estimated at end 1980 - All formations.
- Table 2 - Standing "volumes actually commercialized" (VAC) at end 1980 Undisturbed productive forests
- Table 3 - Estimated areas of undisturbed productive closed forests logged annually (sawlogs and veneer logs) in the period 1981-85
- Table 4a - Growing stock (VOB) estimated at end 1980 - Broadleaved forests
- Table 4b - Growing stock (VOB) estimated at end 1980 - Coniferous forests (NS)
- Table 4c - Total growing stock (VOB) estimated at end 1980 - Closed forests (broadleaved and coniferous)
- Table 5a - Areas of established plantations estimated at end 1980 - Industrial plantations
- Table 5b - Areas of established plantations estimated at end 1980 - Non-industrial plantations
- Table 5c - Areas of established plantations estimated at end 1980 - All plantations
- Table 6a - Average annual deforestation - Closed broadleaved forests (NHC)
- Table 6b - Average annual deforestation - Coniferous forests (NS)
- Table 6c - Average annual deforestation - Bamboo forests (NHB)
- Table 6d - Average annual deforestation - Closed broadleaved, coniferous and bamboo forests (N.f)
- Table 7a - Areas of natural woody vegetation estimated at end 1985 - Closed broadleaved forests (NHC)
- Table 7b - Areas of natural woody vegetation estimated at end 1985 - Coniferous forests (NS)
- Table 7c - Areas of natural woody vegetation estimated at end 1985 - Bamboo forests (NHB)
- Table 7d - Areas of natural woody vegetation estimated at end 1985 - Closed broadleaved, coniferous and bamboo forests (N.f)
- Table 7e - Areas of natural woody vegetation estimated at end 1985 - Open broadleaved forests (NHc/NHO)
- Table 7f - Areas of natural woody vegetation estimated at end 1985 - All formations
- Table 8a - Areas of established plantations estimated at end 1985 - (projections) Industrial plantations
- Table 8b - Areas of established plantations estimated at end 1985 - (projections) Non-industrial plantations
- Table 8c - Areas of established plantations estimated at end 1985 - (projections) All plantations
In the case of tropical America the tables concerning bamboo forests (1c and 7c) and those related to open broadleaved forests formations (1e and 7e) are not shown since the areas of the former have not been estimated and those of the latter have not been broken down by category in all countries. Tables 1d (and 7d) and 1f (and 7f) have, for tropical America, the following numbers respectively 1c (and 7c) and 1d (and 7d).
5.4 Results for the whole of the three regions
Chapter III of the present report briefly sets out the results of the study for the whole of the 76 countries studied, following the same plan used for the country briefs and the regional syntheses. The tables are the same as those supplied in the regional syntheses, the three regions and the whole appearing in line.
Chapter III
THE FOREST RESOURCES OF TROPICAL AMERICA, AFRICA AND ASIA
Seventy-six countries have been studied in the three main tropical regions that have been indicated with their groupings by sub-region in section 5.1 of the preceding chapter. For easier reference the list by region is given again here below:
As all descriptions in the framework of this chapter are bound to be extremely brief, reference should be made to the regional syntheses and to the country briefs (technical reports 1, 2 and 3) for all that relates to the very diverse physical characteristics of the 76 countries studied and the three regions which include them.
The situation and evolution of forest resources is chiefly related to the pressure exerted on them by the human populations, particularly agricultural populations. The following table gives some important indications on population densities per region and sub-region, extracted from volume 33 of the FAO Production Yearbook for the year 1979 updated to 1980 by using the mean annual growth rate of the period 1975-80.
The grouping by sub-regions in the table hides important disparities in the different countries, particularly in tropical America. Thus, for example, the "other Caribbean" include French Guiana and Haiti which are in diametrically opposed situations. Nevertheless many-useful conclusions can be drawn from this table which deserves careful examination. Some of the more important conclusions are given here below:
- the growth rate of the agricultural population is everywhere less than that of the total population, the difference being in the order of 1 point (on 2.6 points) for all the 76 countries together. The agricultural population grows by less than 170 per year in tropical America (1.1 million inhabitants), by about 2% in tropical Africa (5.1 million inhabitants) and by about 1.5% in tropical Asia (12.3 million inhabitants). Out of the 50.7 million yearly increase in the total population of the 76 countries studied, 18.5 million (i.e. approximately a third) correspond to the growth in agricultural population;- the sub-regions with low agricultural population density (less or equal to one person per 10 ha of tree area) are in fact those where the forest cover is the least threatened: CARICOM, Central Africa, Tropical Southern Africa, Papua New Guinea. The low density figure of Southern tropical Latin America is explained by the fact that the central part of the Amazon is poorly populated. Nevertheless, the mass of the Amazonian forest is threatened at its borders where the population density is higher than in the centre;
- on the other hand the sub-regions with a high agricultural population density, (more than one person per 2 ha of tree area), are those where regression and/or degradation of the forest cover, are more serious: Central America and Mexico, the Northern savanna regions of Africa, West Africa, East Africa and Madagascar and the sub-regions of tropical Asia. With the exception of French Guiana, the sub-region "other Caribbean" is also in the same situation. In spite of the very high density of the agricultural population in South Asia, the forests of this sub-region, while still under threat, are relatively less cleared than those of other Asiatic sub-regions because of their intensive management (particularly in India);
- for the 76 countries studied as a whole, the average density of population is exactly one person per hectare of tree formation not yet affected by agriculture. This figure can be compared to that for Europe which is 3.5 persons per hectare. The same comparison for the agricultural population gives 0.60 person per hectare as an average for the 76 tropical countries studied and 0.53 for Europe. It can be noted that these two latter figures are very similar whereas the densities of total population are quite different.
1. PRESENT SITUATION
1.1 Natural woody vegetation
1.1.1 Introduction
Indications have been given in paragraph 2.1.1 of chapter II of the main existing regional classifications of vegetation that have been taken into consideration in this study for the analysis of the woody vegetation of each of the three tropical regions. Section 1.1 of the third chapter in each of the regional syntheses gives indications on these classifications. There are also regional descriptions in the same section in the reports for Africa and Asia. Finally, each country brief has a more or less detailed description of its main woody formations. In this report we will limit ourselves to the estimates of areas of large vegetation formations for the 10 countries and territories studied in tropical South America and for the 37 countries studied in tropical Africa, as these have been estimated by dot counting respectively on the "Vegetation map of South America" at 1/5 000 000 scale (prepared for Unesco by the Institut de la carte internationale du tapis végétal) and on the "Vegetation map of Africa" (by F. White) at 1/5 000 000 scale for Unesco/AETFAT.
Areas of vegetation types for the 10 countries and territories studied in tropical Southern America taken from the UNESCO/C.I.T.V. vegetation map of South America at 1/5 000 000 scale.
Tropical Africa[a], [b], [c], [d]
Areas of vegetation types and mosaics for the 37 countries studied of tropical Africa according to UNESCO/AETFAT vegetation map of Africa at 1/5 000 000 scale (compiled by F.White).
Tropical Asia
We give here below the original English nomenclature for the main forestry formations in Asia as these have been classified by Champion and Seth, van Steenis and Whitmore respectively.
- Champion and Seth classification
"Tropical wet evergreen forests"
"Tropical semi-evergreen forests"
"Tropical moist deciduous forests"
"Littoral and swamp forests"
"Tropical dry deciduous forests"
"Tropical thorn forests"
"Tropical dry evergreen forests"
"Subtropical broadleaved hill forests"
"Subtropical pine forests"
"Subtropical dry evergreen forests"
"Montane wet temperate forests"
"Himalayan moist temperate forests"
"Himalayan dry temperate forests"
"Sub-alpine forests"
"Moist alpine scrub"
"Dry alpine scrub"
- Classification by van Steenis
"Rain-forest"
"Dipterocarpus forest"
"Agathis rain-forest"
"Borneo ironwood rain-forest"
"Casuarina forest"
"Pinus forest"
"Freshwater swamp and peat forest"
"Sago swamp forest"
"Mangrove forest"
"Secondary forest"
"Savannahs"
"Monsoon (or seasonal) forest"
"Teak forest"
- Classification by Whitmore (based on van Steenis)
a)"Tropical rain forests"
"Tropical lowland evergreen rain forest"
"Tropical lower montane rain forest"
"Tropical upper montane rain forest"
"Tropical subalpine forest"
"Heath forest"
"Forest over limestone"
"Forest over ultrabasic rocks"
"Beach vegetation"
"Mangrove forest"
"Brackish-water forest"
"Peat swamp forest"
"Fresh-water swamp forest"
"Seasonal swamp forest"
"Tropical semi-evergreen rain forest"
b)"Monsoon forests"
"Tropical moist deciduous forest"
"Other formations of increasingly dry seasonal climates"
1.1.2 Present situation of the woody vegetation
Present areas (end 1980 - tables 1) [7]
- Table 1a: Areas of closed broadleaved forests (NHC).
The 23 countries of tropical America have more than 56% of the closed broadleaved formations of all the 76 countries which cover a total area of 1 160 million hectares. Brazil alone has nearly 31% and the 10 countries and territories of tropical South America (Bolivia, Brazil, Colombia, Ecuador, Guyana, French Guiana, Paraguay, Peru, Surinam and Venezuela) more than 52%. A quarter of the closed broadleaved forests are found in the 16 countries of tropical Asia and only 18% in tropical Africa.
The closed broadleaved forests that are unproductive either for physical reasons (stand and/or terrain conditions) or for legal reasons (mainly forests situated in national parks or equivalent reserves) are proportionately more widespread in tropical Asia than in the two other regions. This reflects the fact that on the one hand the lowland forests have been, to a larger extent in this region, given over to other land use and, on the other hand, that the reservation for purposes other than wood production is more highly developed.
The undisturbed productive closed broadleaved forests, i.e. more than 60 to 80 years of age and not disturbed by logging, cover a total area of nearly 670 million hectares of which 68% are in tropical America (65% for the 10 countries and territories of tropical South America), 18% in tropical Africa (nearly 17% for the Cameroon-Congolese forest mass alone) and only 14% for tropical Asia.
The highest proportion of productive closed broadleaved forests that are logged, or managed, is clearly in tropical Asia (49% of the productive closed broadleaved forests) and only 27% is in tropical Africa and 10% in tropical America.
The intensively managed closed broadleaved forests of the 76 countries as a whole only represent 4.4% of the productive closed broadleaved forests. 78% of these are concentrated in one country only (India), and only 8 other countries (1 in America, 4 in Africa and 3 in Asia) have a more than negligible proportion of their closed broadle
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