Most remaining unlogged areas of forest outside the limited extent of Protected Area systems will be exploited for timber within the next few decades. The logged forests, except where excessive machine operations, fire or illegal cultivation have caused intensive damage, still retain much of the original plant diversity and are often apt for recolonisation by the major fauna (Johns 1988 and 1992; Whitmore and Sayer 1992). The effect of the initial logging on the forest structure, composition and regeneration have been well documented and the procedures to minimize damage and improve cost-effectiveness fully described (e.g. Nicholson 1979; Dykstra and Heinrich 1992). Ideally harvesting operations in production forests aim to mimic processes of natural gap formation in order to provide a sustainable yield of timber without radically altering the composition and structure of the forest as a whole. Retention of unlogged areas amounting to only 5% of an intensively logged forest may be adequate to conserve populations of vertebrate species regarded as intolerant of logging (Johns 1992), and a single cycle of logging need not reduce species richness among the tree populations (Whitmore and Sayer 1992) provided adequate regrowth is present and not severely damaged during logging, or seed for subsequent regeneration is available in the soil seed bank or adjacent areas.
Major impacts on both species richness and the genetic resources of the prime timber species, especially those more shade-tolerant and characteristic of mature-phase forest, are likely to be associated with the second cycle of logging and subsequent harvesting. The length of the cutting cycle will be critically important to the maintenance of satisfactory breeding populations of the principal tree species. Even when small areas, such as Virgin Jungle Reserves may be left unlogged the progressive effects of forest fragmentation, and isolation, on gene flow, inbreeding rates, genetic variation, seed fertility etc. will decisively affect the genetic resources. There may be impacts on key pollinators or seed dispersers, as well as on soil structure and even soil chemistry (House and Moritz 1991).
Coordinated long-term studies are needed to guide the management of logged forest for the conservation of species richness and genetic resources, including where necessary remedial management (Ng 1983).
Although forest management can be defined in various ways (Vanniere 1975; Philip 1986; FAO 1992a), there is general agreement that it should consist essentially of taking firm decisions about the future of a particular area of forest, planning and implementing action to achieve those objectives and monitoring the results. It depends ultimately on the national forest policy and its basic components are the definition of objectives, planning, control, protection and records. It is also concerned with the allocation of resources to meet the defined objectives and it is commonly the wide disparity between the objectives and the resources provided to meet them that causes the greatest impacts on the forest. As used here it is taken to include both the controlled harvesting of timber and associated silvicultural operations aimed at the sustainable provision of specified goods and services from the forest. An essential aspect is that the land should remain in forest use after harvesting and that the operations should be conducive to adequate regeneration and to the maintenance of the environmental and social functions of the natural ecosystem. This implies involvement and prior consent by all land users, control and continuity of purpose, which are also essential elements for the conservation of the forest's genetic resources.
Genetic resource management can only be effective if it is an integral part of land use management as a whole (FAO 1989a). The objectives of in situ conservation may involve various approaches to land use, including multiple use production areas and timber production forests as well as fully Protected Area systems, in the attempt to reconcile the dual requirements of present day demands for revenue and basic human needs (food, wood and other forest products), with long-term conservation objectives. Ideally this requires a comprehensive national land-use policy and plan, embracing an appropriate forest policy and based on a national inventory of the forests, including specific attention to plant species of socio-economic importance and conservation concern. Failing that a broad zonation of vegetation, following the principles of the Biosphere Reserve Programme (Unesco 1984), may be used to focus the conservation objectives to the most important areas, which may then be given special reserved status, within fully-protected categories of land. In reality the pressures of increasing human populations and related economic development programmes on the land and natural resources severely restrict the areas likely to be set aside and retained as National Parks or equivalent, fully protected reserves. The potential contribution of production forests to the conservation of genetic resources is therefore important and may be high, given a conservative and sustained approach to forest management, based on natural regeneration systems. The deliberate inclusion of genetic conservation objectives in the management plans of production forests may be essential, to secure the necessary range and diversity of sites for an efficient national conservation network.
The initiation of tropical forest management, first in the Indian sub-continent, and subsequently in Africa (FAO 1989b; FAO 1989c) included the establishment of firm administrative control over the forests, for example with the designation and demarcation of a “Permanent Forest Estate” whose boundaries and use could be changed only by decision at the highest levels of national authority. Although this authoritarian approach has sometimes provoked local opposition, and there is now general acceptance that the security of the forest cannot be assured without the consent and involvement of local people dependent on the resource, the establishment of the Permanent Forest Estate has been a powerful element in the conservation of genetic resources. Although in many cases the objectives of sustainable timber production have not been sufficient to ensure the retention of all of the reserved forest estate from reallocation to permanent agriculture, or from illegal encroachment, in most tropical countries legal protection for productive forests has had an important and positive impact on the conservation of their genetic resources. However there have also been severe negative impacts from the often excessive exploitation (unaccompanied by adequate control and management to ensure regeneration) resulting from short-term political, financial and economic pressures.
Most recent reviews of tropical forest management (Masson 1983; Mergen and Vincent 1987; Schmidt 1987; Wyatt-Smith 1987a; FAO 1989b; FAO 1989c; FAO 1992a; Poore 1989) conclude that management of the tropical forest as a renewable and truly sustainable resource is technically possible and that the past failures or abandonment of attempts at the sustainable production of timber in tropical forests have been due to socio-economic or political pressures. These have frequently imposed severe constraints on the resources available for the various aspects of management referred to above, resulting in part from the failure to recover adequate revenue from the exploitation of the resource, and/or failure to reinvest such revenue in the regeneration and management of the forest (Repetto and Gillis 1988).
At the root of the problem is the weakness of the national economy in most tropical countries combined with the scarcity of capital to invest in development. The forest itself has been treated as a source of finance to support development in other sectors of the economy and while in total this source of funding has been sufficiently large to make exploitation worthwhile, the apparent returns per unit area of forest are commonly too low to secure the necessary level of investment for sustainable management, or even to retain the land against pressures for alternative land use. Even when the arguments for the long term economic benefits from reinvestment in forest management may be accepted urgent short-term financial constraints, coupled with short-term interests of concessionaires, logging enterprises and other concerns, may lead to excessive exploitation without regard to forest regeneration. This is encouraged by short-term concession agreements which provide no motive for longer-term planning. In order to recover the investment in large-scale machinery and road construction the logging companies frequently seek maximum returns from harvesting at minimum costs, and with minimum concern for environmental impacts. Where market demand is highly selective the exclusive concentration on the extraction of the best phenotypes of the most valuable species will have negative (dysgenic) effects on subsequent generations, if such interventions are carried out without due consideration to regeneration potential and the quality of the next generation crop.
Where a broader range of species, including many lesser-known or lesser-used species, are marketable there may be potential for greater revenue, providing the opportunity for increased reinvestment in forest management. In practice, however, although the more intensive felling has tended to increase profits, reinvestment has remained static or even been reduced; the forest has in these cases been left to recover naturally without regard to species composition. If logging damage to the advance regeneration and to the site conditions for seedling establishment were closely controlled the harvesting of a wide range of timbers might be more compatible with the conservation of a similarly broad range of species, than the very selective logging characteristic of earlier exploitation regimes (see for example the Ghana case study Part II). However without strict controls over road construction, logging plans, timber marking, harvesting and extraction there must be a danger of severe ecological impacts on the site capability, and on the genetic resources especially of the slower-growing species characteristic of the mature-phase “climax” forest.
The introduction of heavy mechanical equipment for timber exploitation, together with increased demands for a wider range of tropical timber species, has had an overwhelming impact on the species and genetic diversity of some natural forests. The effect is to shift the composition of the forests in the felled areas towards relatively few predominantly fast-growing pioneer species characteristic of the earlier stages of the ecological succession. Management for the in situ conservation of genetic resources must give priority to the principal economic species, some of which at least will be fast-growing pioneers or gap-opportunist species, which will be favoured by a certain degree of canopy opening. However the effect of large-scale and extreme reduction of the forest canopy which is associated with heavy mechanical logging of a wide range of species is most likely to favour very short-lived pioneers with timber low in density and durability. It is certain to discriminate, at least in the short term, against the multitude of slower-growing shade-tolerant species, including some high quality cabinet woods and veneer timbers. The overall impact of these interventions is therefore to reduce the range of species of known economic value, uniformly in favour of a narrower band of fast-growing, low to medium density species. At the same time there is likely to be a reduction in the biological diversity of the ecosystem as a whole, both flora and fauna, unless certain areas of the forest are excluded from simultaneous, intensive logging regime. Economic pressures to maximise the returns from the investment in logging equipment, roads and related infrastructure have frequently overridden such ecological considerations.
Volume yields in naturally regenerated tropical moist forest are likely to be on average only 2 to 3 m3 per hectare annually, although in some cases silvicultural operations and rational management might increase this by a factor of three or four times, where there is ample regeneration of marketable species and where site conditions are favourable (Wyatt-Smith 1987a). A common feature of management systems aiming to increase the yield of valuable species in this way is the elimination, usually by poisoning, of unwanted and competing trees. This and other “refining” operations, if maintained consistently through successive cutting cycles, will also reduce the diversity of species in the areas treated but need not do so over the forest as a whole, if selected areas were excluded from such treatments or were treated to favour different components. In most existing operations the loss of yield involved in such exclusion would be regarded as unacceptable on purely economic grounds.
The impact of the international trade in tropical timber on the genetic resources of particular genera and species has been assessed in a recent study undertaken on behalf of the International Tropical Timber Organisation (ITTO) by the World Conservation Monitoring Centre (WCMC 1991). This study compiled data and expert observations on 1 868 tree species, and assigned them to conservation categories in accordance with the IUCN system. Of these 304 species were classified as threatened at a global level and 190 as threatened in two or more countries. The reliability of the data may be questionable since there is little available information based on detailed forest inventory and the assessments are therefore based largely on the opinions of specialists in the various geographical and botanical fields. Particular attention was given to the family Dipterocarpaceae, for which the study claimed to have achieved a relatively complete assessment of the conservation status. Even allowing for some uncertainty and possible exaggeration of the degree of depletion or threat the study revealed a serious impact on the genetic resources of this important family of high quality timbers. The very intensive logging now being carried out in several of the countries in which species of this genus occur naturally, must give cause for concern unless urgent attention is given to their sustainable management within which harvesting is only one step; and to genetic conservation measures, carried out in parallel with their use.
The ITTO study covered countries in Africa and Asia in 1991/92. In Latin America another aspect of the market impact on forest genetic resources has been identified where the demand for mahogany (Swietenia macrophylla) has led to highly selective harvesting of good phenotypes of the species over large areas without provision for subsequent protection of the regeneration and management to ensure its diversity and quality (Monbiot 1991). The danger of severe dysgenic effects and extinction of local populations is clearly a possible consequence of the market forces in this case.
In general the effect of economic and market forces has been to impose the reduction of species and genetic diversity in the timber-producing forests. This has been the result of very narrow, selective markets, and failure to re-invest part of the revenue in forest management, thereby enforcing low-cost “blanket” management systems with short-term objectives. The inadequacies of economic theory and analysis relating to natural management systems in tropical mixed forests (Leslie 1987) relate particularly to the need to widen the scope of the analysis beyond the short-term benefits to the agencies and individuals most directly involved, to include the broader interests of the nation and society as a whole, and of future generations. This applies particularly to the values attached to the genetic resources of the forests. To the extent that the timber production areas can also be managed to conserve genetic resources this additional objective should reinforce the economic case for natural forest management to be governed by ecological as well as economic considerations.
Even the much narrower range of overall genetic diversity that will result from repeated extensive harvesting and refinements of the forests is likely to be much greater than if the same area were converted into forest plantations, and certainly substantially greater than that which would result from most alternative forms of land-use. However, many species and populations, especially those characteristic of the primary or mature-phase forests, will be lost unless the current severe constraints on the funding of natural forest management are reduced. Increased funding (including the re-channelling of revenue back into the forest) would allow more deliberate and diverse management of the tree populations, possibly at the expense of some loss in harvested volume. This loss might be partly offset by an increase in unit value from the management of selected areas on longer rotations for higher quality timber.
Whereas rethinking of the economic and financial constraints on natural forest management seemed unrealistic earlier, and may still be so for most of the production forests, the economic value of genetic diversity is now increasingly recognised as of international concern. That value, and therefore the costs that might be borne for conservation, will be dependent on the location, composition and existing condition of each specific area of forest.
The scientific basis for the conservation of species and of their genetic resources depends essentially on the study and interpretation of taxonomic information on genetically determined differences and affinities, their patterns of natural distribution (chorology) and the ecological basis for their occurrence. These three interdependent sets of data which should form the basis for drawing up sound conservation strategies, are inadequate in the tropics and in many cases non-existent. Very often the only data available are the result of forest inventories concerned primarily or exclusively with stocks of harvestable timber. The techniques for efficient surveys of the standing timber resources in the forest have shown considerable progress in the past 30 to 40 years (FAO 1989b) and there has been increasing emphasis on the need for National Forest Inventories and for detailed and more comprehensive inventories of selected areas. However, all too often such inventories have provided little of the information needed to plan the long term, sustainable management of the forest, but have been confined to the determination of the marketable volume of a limited number of so-called economic or potentially economic species (Masson 1983). Little regard has been paid up to now to the determination of the actual composition of the forest or its condition after logging.
Inadequate information on the species composition of the forest is one of the main problems confronting natural forest management, both in terms of the forest's full economic value and its regeneration potential (Wyatt-Smith 1987b). Some of the important questions to be answered in this regard are the adequacy of existing levels of seedlings, saplings and advanced growth of the marketable species as the basis for the future crop, both before and more importantly after logging. Assessment of regeneration was an integral component of the earliest attempts at natural forest management, for example in Malaysia and Nigeria, but latterly the tendency has been to reduce rather than to increase the time and manpower resources devoted to such surveys, and thereby to limit the level of detailed information available even in respect of the preferred economic species. However in recent years, with the development of conservation biology as an applied science, it has become increasingly clear that more detailed studies and surveys must be an inseparable component of forest management systems to produce an adequate scientific basis for conservation action.
Diagnostic sampling to determine the stocking and silvicultural conditions of young stems of “desirable” species below the exploitable girth limit is a common practice in the more deliberate attempts at natural forest management (FAO 1989b) and there is a tendency for inventory and resource assessment in advance of logging to be taken further, to extend beyond commercial timber resources to non-timber products, including those of interest to local communities (FAO 1989c). Such action is essential to obtain a more complete valuation of the forest in support of the conservation of a wider spectrum of valuable genetic resources (see also the Ghana case study).
The central and traditional component of forest inventory, namely the accurate assessment of the allowable cut and sustainable yield of timber, is vital to conservation of the resource, to ensure that the rate of harvest should not exceed the regenerative and growth capacity of the forest. This requires an accurate knowledge of the growing stock, its distribution by species, size classes and location, and an understanding of how these change with logging and silvicultural treatments. Availability of accurate forest inventory and stock maps in reducing logging damage and protecting the regeneration is also essential in the conservation of genetic resources. However such inventory data are insufficient as a basis for more positive action to identify and conserve the most valuable components of genetic diversity. Given the high proportion of the cost of inventory operations that relates to the actual access to and work in the forest the additional cost of collecting a wider range of data and observations in the course of the timber survey can be relatively low. Moreover the widespread availability of powerful electronic computing facilities for the handling of large and complex sets of data has largely removed that constraint on the collection of an increased range and volume of field data, in the course of forest inventory.
In general 10% of the tree species in a tropical forest comprise at least 50% of the stand (Ashton 1988). Rapid extensive surveys may give guidance to conservation priorities not only in terms of species richness but also in respect of the genetic resources of a forest. Recent studies by Hawthorn in Ghana indicate the potential value of broad botanical surveys in association with forest inventory in developing strategies for the conservation of forest genetic resources (see also the Ghana case study).
For the forest inventory to serve its full purpose in assisting the conservation of forest genetic resources it must attempt to assess the relative genetic value of a given area of production forest, for example in regard to the range of distribution of selected species or forest types, in relation to other managed or reserved areas, including the fully Protected Area system of National Parks etc. This information could help determine the most efficient combination of the minimum number of sites needed to cover species, populations and communities at the minimum level essential for conservation of the desirable range of diversity. Given the very large numbers even of tree species in the tropical forests, and the need to include surveys of some other socio-economically important plant species, or of species essential to the functioning of the ecosystem, and therefore to the overall management of the resource, it is often necessary to adopt a compromise between detailed biological surveys and more general assessments, based on variations in landscape or other environmental features. It may be assumed, for example, that much intra-specific (provenance) variation, of potential economic significance, follows patterns of variation in the environment and in the plant community as a whole.
A key to efficient and cost-effective inventory is at the planning stage, to ensure inclusion of an appropriate range of botanical, ecological and sociological expertise, for example, both in the design and in the execution of the survey. Given the range of expertise and strength of interest in many universities and research institutes in both tropical and industrialised (often aid donor) countries in such scientific investigations in tropical forests, the additional human resources needed may often be available at comparatively little extra cost, compared with the expenditure on the basic inventory, and in relation to the value of the additional information to be derived from such expert involvement.
A particular aspect of this planning phase which may require expert involvement is the planning of data capture, handling and analysis. The widespread availability of small but powerful computing capabilities for data analysis has also transformed the possibilities for obtaining an understanding of forest composition and genetic diversity from limited data. Approaches to the development of inventory procedures and growth models for the management of tropical forests are advancing rapidly (e.g. Vanclay 1989; Alder 1990) and will progressively gain the capacity to incorporate broader information relating to the management of the genetic resources of the forest. Simulation of the variability and complexities of population distributions is already possible using some stochastic models such as those designed to measure the average number of occurrences in a given area, and to reveal patterns of their variability (Jeffers 1982). This information can be an important aid to selecting locations for in situ conservation.
Sustainability as an objective of forest management demands that forest inventories be planned to look far beyond the assessment of marketable volume to the establishment of baseline data for the continuous monitoring of forest condition, and the implications for the conservation of genetic resources. Among these are the retention of sufficient individuals of “keystone” species to maintain their own breeding populations and therefore the long-term contribution of that species to the functioning of the natural forest ecosystem. This requires the identification and recording of such species in pre-logging inventories, so that sufficient numbers, with an appropriate distribution in the forest, are marked for retention, based on a sufficient understanding of the forest dynamics.
The aspect of forest dynamics which has attracted most attention in relation to timber exploitation is the growth and yield of the principal marketable species. The lack of reliable annual growth rings in the timber of most tropical tree species, and therefore of convenient “short cuts” to the determination of increment, together with the complexity of the growing conditions and species composition in the forests, has made predictions of yield difficult (e.g. Kemp and Lowe 1970). Despite the progressive development of systems of Permanent Sample Plots (continuous forest inventory plots) in representative samples of forest in a number of countries the basis for calculations of growth and yield is still generally weak. Probably the best level of prediction has been achieved in Queensland, Australia (Vanclay 1989). However even in those intensively studied forests there is very little if any reliable information on the relative importance of genetic and environmental factors in determining growth rates of individual trees in the natural stands.
The influence of competition from other vegetation on the relatively small proportion of “desirable” stems has been the basis of management interventions to effect improvement thinnings to favour the growth of the potential final crop trees (Hutchinson 1987; Maitre 1991; FAO 1989c). The first step in this treatment, as applied in Sarawak (Hutchinson 1987) is to group the species into “wood quality” categories, to arrive at lists of desirable species, and then to assess and attempt to predict their response to different levels of release from overhead shade and competition resulting from commercial logging or subsequent thinning of the stand. For this purpose the species are allocated to ecological groups according to their degree of shade tolerance and/or capability to increase growth rapidly in response to release.
Classical forest management started from attempts to understand and utilise such ecological processes and interactions, and particularly the natural cyclical changes in the progression from gap colonisation by pioneer species to the mature or late successional forest condition. Arbitrary divisions into gap-phase, building-phase and mature-phase forest development are now commonly recognised (Whitmore 1990). The concept of “forest gap-phase dynamics” appears to apply as a general model, possibly with local variants, in a wide range of forests in all tropical regions and although it is an oversimplification to recognise only “pioneer” or “climax” species the definition of two broad groups or “guilds” based on their behaviour in response to gap creation has proved useful in approaches to natural forest management (Whitmore 1991). It is also important in approaches to in situ conservation of forest genetic resources, particularly those of the principal economic tree species.
In all tropical rainforest floras there are fewer pioneer than climax species (Whitmore 1990) and the pioneer genera are less likely to include narrowly endemic member species of very restricted geographic range. Their efficient systems of seed dispersal are probably responsible for their generally wide range of distribution and reduce the possibilities for the development of localised genetically distinct populations.
The complex interrelationships in pollination, seed dispersal, food web and plant web systems described earlier are important both for the attempted regeneration and management of timber species, particularly those in the “climax” guilds, and for in situ conservation of forest genetic resources. Without adequate understanding of the ecological processes and relationships the attempts at natural forest management must rely on “blanket” application of silvicultural treatments with unpredictable and possibly perverse results. However it has latterly proved impossible to justify the necessary expenditure on detailed ecological studies in terms of the increased yield of timber alone over the period of one or two cutting cycles or short rotations. Nevertheless recent reviews of management methods have emphasised the inadequacy of “blanket” canopy treatments and the necessity for improved knowledge of the autecology of individual species, and not only those with marketable timbers (FAO 1989b).
The field of reproductive biology, embracing studies of pollination, seed dispersal and predation, and the dynamics of regeneration banks of seed, seedlings and saplings, which are clearly important in genetic resource conservation, have also been identified as necessary to the forest manager (Palmer 1989). The case study of Cordia alliodora in Appendix 1 shows the level and intensity of research needed to provide reliable information for a single species. The number of species requiring such study even in a single forest, is very large, and the resources of skilled manpower are very limited.
Seed dispersal biology is directly relevant to natural forest management, particularly in respect of the mature phase species, many of which have high value timbers, and are characterised by the production of large seeds. There is a growing body of evidence that the frequency and density of such species in the natural forests is limited by seed predation and that chances of survival are improved by dispersal away from the vicinity of the parent tree (Terborgh 1990). A good example is the dependence of Virola surinamensis on distribution by toucans and other large frugivorous birds, without which it would be unable to recruit seedlings, and the species would face local extinction (Howe 1990). An understanding of the identity and behaviour of animal dispersers, and their possible dependence on other tree species for food or nest sites, is an area of common concern to both forest managers and forest geneticists concerned with conservation.
The regeneration potential of the desirable species is of key importance in the management of the productive forest estate and clearly fundamental also to the conservation of their genetic resources. For in situ conservation natural regeneration is the clearly preferable strategy, although some aspects of artificial regeneration, such as enrichment planting using seed or seedlings randomly obtained from the same natural stand, may sometimes be acceptable and desirable. The encouragement of natural regeneration is likely to be the cheapest option for timber production objectives also, provided that it can be easily and confidently obtained. In practice, however, it has proved to be one of the most difficult and uncertain aspects of management in tropical forests, despite having been the subject of much field study and experimentation for over a century.
The problem is not peculiar to the tropical forests, but is evident from the large areas of previously forested and now barren land in the Mediterranean and some temperate regions. Grazing and browsing by domestic livestock have had a major influence in such areas, and in the more densely populated tropical forest regions, for example in India, even in tropical forests of high production potential, such as the Sal (Shorea robusta) and evergreen forests (FAO 1989c) despite the long history of research and study by trained staff. Similar failures have been common elsewhere in Asia, except in some of the richer dipterocarp forests, where as a result of the range of desirable species whose silvicultural characteristics are favourable to promotion by controlled canopy opening, satisfactory, although by no means predictable, natural regeneration has been more often achieved. Failure to ensure adequate regeneration of the selected economic timber species proved a fundamental problem in many African forests (Nwoboshi 1987; Kio and Ekwebelan 1987; FAO 1989b) and was a principal reason for the development of forest plantations in African countries, as an alternative to natural forest management.
Among the most important aspects of regeneration behaviour are the frequency of seed years, the length of seed viability, seedling survival, the pattern of distribution and abundance of seedling regeneration on the forest floor, the tolerance of shade and response to light and the competitive potential of the preferred species under different degrees of canopy opening. The complexity of the interactions in the natural forest is such that the provision of a set of environmental conditions guaranteed to favour the regeneration of a few selected species is virtually impossible, without detailed study of the actual state of each limited area of more or less uniform conditions within the diverse mosaic of the forest, and of the autecology of all the principal species. In practice diagnostic sampling often by means of systematic parallel transects through the forest, is used to determine the overall adequacy of stocking of young stems of desirable species, which is found to survive undamaged after logging is complete, as the basis for the next crop. A diversity of sites and silvicultural systems will be likely to create increased diversity, thus being an advantage from the genetic resources point of view.
A shift in approach to the management of the regeneration stage, from earlier attempts to control the composition and development of the seedling population to the acceptance of the largely accidental composition actually obtained, is reflected in the procedures for regeneration sampling. For example in the earlier development of the Malayan Uniform System (MUS), which was among the first and most successful attempts at management in the tropical moist forests, a three-stage linear sampling regime was used to determine different stages of regeneration development before logging was undertaken. This procedure was later modified by merging the three stages into a single linear regeneration sampling operation after logging was completed (Wyatt-Smith 1987b). The change represented the acceptance that economic imperatives rather than silvicultural considerations, are decisive in determining management practices. The MUS as originally designed made provision for situations where the level of seedling regeneration was found to be inadequate, by proposing deferment of logging until adequate regeneration was obtained. However in practice the inadequacy of regeneration stocking before felling was not allowed to hinder the progress of exploitation (Ismail 1966).
In the Malaysian dipterocarp forests the effective fruiting years are the massive long-interval ones (Appanah and Salleh 1991), and it is preferable to log following a mass fruiting year. Silvicultural operations to kill unwanted “weed” species and to liberate juveniles of desirable species can be increased following abundant fruiting, for maximum benefit in the improvement of future timber production. The abundant regeneration which may be achieved by deferment of logging until after a heavy fruiting year offers maximum possibilities for effective silvicultural operations to improve the composition of the final crop; it will also favour conservation of the genetic resources of the species favoured for commercial utilization. It seems probable that the small amount of seed of given species produced between mass seed years may be provided by a small and possibly distinct segment of the population; as the regeneration resulting from such seed will not be representative of the population, its value for conservation will be limited, unless complemented by seedlots/regeneration over a range of years..
The importance of leaving seed trees of good phenotypic quality at the time of logging, particularly if regeneration sampling has revealed low levels of established seedlings and advance growth of the desirable species, is a further instance of close coincidence of interest between the objectives of production and those of genetic resource conservation. In practice, however, this vital aspect has been commonly overlooked or overridden by the pressures for maximum harvest yield and profit. The retention of a number of large seed bearers after the main logging operation does present some disadvantages in subsequent management of the stand if they are so numerous as to cause depressive shade or competition (Catinot 1986), or if they are subsequently harvested, with related extraction damage to the regenerating forest. However the effective loss in production is slight in comparison with the dangers of progressive deterioration in the genetic quality of the population through effective reliance for regeneration on residual, probably less vigorous and less desirable phenotypes to complement soil seedbanks and existing seedling regeneration, if these latter ones are inadequate. Despite the practical difficulties and dangers of attempting to select genetically “superior” individual trees in natural tropical forests the real dangers of dysgenic effects from the selective, systematic removal from the breeding population of the best and most vigorous phenotypes should not be ignored. More information based on solid research on this aspect is urgently needed.
Reliance on natural regeneration systems in production forests undoubtedly offers important opportunities for in situ conservation. The regrowth that follows heavy logging will favour pioneer (gap-phase) species and large-scale clear cutting typically leads to the complete dominance of soft-wooded, low density timber trees (Jordan 1986). As primary forests are progressively cleared or exploited the populations of many prime hardwood species characteristic of climax, mature-phase forests must decline unless specific measures are taken to maintain them. The role of the seedling populations in the natural regeneration of such species is particularly important. For example the Asian dipterocarps generally require at least a small gap in the canopy to develop to adult size but the chance of seeds naturally being placed in such a gap is low due to poor seed dispersal and infrequent seed years (Ashton 1982). This, combined with the lack of seed dormancy (Ng 1980) gives exceptional significance to the ability of dipterocarp seedlings to survive under the low light intensity on the forest floor until an adequate gap in the canopy occurs. The loss of the seedling population before such an opportunity occurs can have profound influence on the future species composition of the forest. The same is true for other species groups of economic importance in some African and neotropical forests (Whitmore 1991). An understanding of seed dispersal biology, and seed and seedling physiology, at least in so far as they are expressed in the incidence and behaviour of seedlings in the forest in relation to light conditions, must be the necessary basis for the conscious manipulation of species composition for both production and genetic resource conservation objectives.
Pioneer species typically have seeds that can withstand desiccation and may become dormant for long periods in the soil. Wherever a soil seed bank has been looked for in lowland tropical rain forest one has been found (Whitmore 1990). Some pioneers have small, copious and easily dispersed seed which allows for frequent replenishment of the seed bank, or for the rapid colonisation of canopy gaps soon after they occur. Generally, therefore, the need for management interventions to favour the regeneration and conservation of the genetic resources of pioneer species is adequately met by normal logging and silvicultural treatments.
Success in silviculture aimed at the production of timber, has been defined as the achievement of “a stand of fine-timber trees brought to maturity and producing natural regeneration on a site where it has matured before, and where the soil shows no sign of deterioration” (Dawkins 1988). On this definition silviculture in the originally closed tropical forest has been more successful over the past century than has been commonly believed, not only in Myanmar (Burma), India and Malaysia, but to a limited extent in some African and neotropical forests. However in terms of impacts on the genetic resources, and especially on the total range of biological diversity of plants and animals in the forests, silvicultural operations, particularly the use of arboricides, can have far more persistent and discriminating influence than crown manipulation or logging. Insofar as the treatments achieve predictable increases in the regeneration, growth and representation in the final crop of the principal economic species, they are likely also to favour the conservation of their genetic resources. However the treatments have often proved to be unpredictable even in respect of the species they were intended to favour, and in many cases involved the attempted elimination of species which have subsequently proved valuable both for their role in the functioning of the forest and for their acceptability in the international timber markets. Conversely the success of the silvicultural treatments has sometimes been due to their accidental encouragement of the regeneration of species which were not at the time considered desirable, but which are now in substantial international demand.
Silvicultural systems in natural tropical forests may be broadly divided into two main groups. Monocyclic systems, also known as shelterwood systems, aim at a single comprehensive harvest of all marketable timber at the end of the rotation, with reliance on seedling regeneration to form the next crop. Probably the best developed and best known example is the Malayan Uniform System (MUS) under which, as originally designed, the initial logging was followed by poison-girdling of virtually all the remaining trees, down to a specified minimum girth at breast height, by which means the canopy became progressively more open, and conducive to satisfactory growth of the generally abundant regeneration of desirable species, principally dipterocarps. Various attempts at shelterwood systems have been made in all three tropical regions (FAO 1989b; FAO 1989c; FAO 1992a; Schmidt 1991) but problems were commonly encountered with severe climber infestations and failure to induce adequate regeneration of the principal economic species. The increased demand for a wider range of marketable species has made the failure to induce regeneration of the few chosen species less critical and the use of heavy mechanical harvesting and extraction equipment, coupled with the increased market demand, has increased the degree of canopy opening by logging alone, making the need for poisoning of residual trees less necessary. The overall ecological effect of such monocyclic systems is to favour “desirable” pioneer or near-pioneer species, including some with light, pale, general purpose, marketable timber. There are likely to be adverse impacts on the breeding populations and genetic resources of the slower-growing heavier hardwood species characteristic of climax forest not favoured by this silvicultural system and the shorter the rotation (or the more restrictive the selection of “desirables”), the more severe the impact will be over time.
Polycyclic systems involve the selective removal of a limited number of stems on two or more occasions over the full rotation cycle, thereby maintaining a less uniform stand of mixed ages, with reliance on advanced regeneration for the next harvest. Such systems are theoretically capable of incorporating mature-phase climax species at the expense of accepting rather lower volume growth rates, but possibly higher value increments and therefore of conserving a broader spectrum of genetic resources in terms of species and timber qualities. However there may be some danger of dysgenic effects within populations of individual species if the selective felling removes the fastest-growing and most desirable individuals, leaving less vigorous and possibly defective stems to regenerate, in the absence of adequate, existing seedling regeneration and/or soil seed banks. Moreover if the desirable species are a small minority of the larger trees in the forest it may be necessary to undertake (expensive) operations to favour the immature trees of the valuable species, to avoid progressive impoverishment of the stand. However, potentially deleterious influences of selection on genetic quality of the species or the stand in this silvicultural system can be avoided by responsible management and harvesting practices, as were practised for example in Queensland, Australia. Under the Queensland Selection System the deliberate selection of trees to be retained in the forest, and the enforcement of strict logging controls to avoid damage to these selected trees, was designed to guard against possible dysgenic effects of selective logging. Effective operation of selection systems requires skilled and frequent tending of the desirable components of the forests and, especially, skilled and responsible logging practices, which help preserve existing advanced regeneration from accidental damage.
It has been suggested that for the first 30 to 40 years after the initiation of proposed systems of management the distinction between monocyclic and polycyclic systems lies more in the future intentions and expectations than in real and irrevocable differences in practices and in the structure of the forest (FAO 1989b). The essential question in regard to the conservation of genetic resources is the extent to which the harvesting practices and silvicultural systems allow for the retention of a wide spectrum of potentially valuable genetic diversity. This is most likely to be achieved if different forests, and different sections within the same production forest, are subjected to different systems, based on ecological principles to favour the regeneration and bringing to maturity of different elements of the main “guilds”, including the climax species. Such management systems would increase the complexity and cost of harvesting and marketing, and might therefore be judged as uneconomic on recent thinking, which has tended to favour very low cost and minimum intervention approaches, since the apparently low level of financial returns per unit area of natural forest has been considered unable to bear the cost of intensive skilled management (see Mergen and Vincent 1987). This implies a management strategy restricted by the forced acceptance of the fortuitous composition of the residual growing stock after logging, with any subsequent tending limited to “blanket” operations applied without discrimination across large areas of initially diverse forest. If accompanied by the search for additional uses and market outlets for the range of timbers actually produced, the resulting balance between revenue and expenditure may appear favourable. However in terms of the impact on the genetic resources such “blanket” operations are likely to cause a progressive loss of over-all diversity, particularly through the impacts on the breeding populations of the slower-growing species characteristic of mature-phase forest.
However, genetic losses are not inevitable since the composition of seedling regeneration and advance growth left after a single logging operation, provided that it does not remove too high a proportion of the growing stock (e.g. 20 to 30 m3 per hectare on average), is likely to contain representatives of all species and guilds. These will probably be adequate to permit the restoration of genetic diversity and the deliberate encouragement of selected elements through subsequent tending, especially if different sets of elements are favoured among the management units. The practice of “liberation thinning” (Hutchinson 1987; FAO 1989c; Maitre 1991) is an example of the deliberate selection and promotion of individual stems to form the final crop, based on the residual advance growth after logging. It allows for the encouragement of a range of desirable species, presently according to lists based on timber qualities, and in accordance with assessment of the ecological requirements of selected species in terms of their likely response to treatments aimed to manipulate the overhead canopy and competition. Once the release of the selected “leading desirables” to form the final crop has been assured this system can permit the retention of a wide range of other species and therefore, if applied over large areas of diverse forest, can be consistent with the conservation of a broad range of species and genetic resources (Hutchinson 1991). Depending on the criteria used to select the “leading desirables” the system could be used to achieve ecological and conservation objectives, at the expense of some reduction in yield of the faster-growing pioneer component of the crop in some areas of the forest.
Ng (1983) has drawn attention to the increasing need for “remedial management” in Malaysia in order to attempt to restore and to maintain the structure and composition of areas of mature forest. While current trends to maximise production from the timber-producing areas are not conducive to the adoption of less intensive harvesting, the growing strength of both the national economy and the conservation consciousness in Malaysia may permit such ecological considerations to be applied in selected forest areas within a decade or so. The possibilities for such “remedial management” will be dependent on research in progress or to be initiated now.
The case studies in both Ghana and India illustrate other approaches to “remedial management” of production forests, to restore and maintain a sustainable and productive system.
While the forest areas successfully managed in this way will certainly be different from the mature natural forest, their contribution to the conservation of genetic resources, within the context of a National Strategy for Conservation (see Section 5.1) which includes a range of forest conditions and management systems, must be very high in comparison with any alternative form of land use that might realistically be considered. Provided that the forest after logging is allowed to regenerate naturally, and is not subject to conversion to other land use, the options for conservation in situ will remain open. However they will be most heavily influenced by the care exercised in the logging, its intensity, and the interval allowed before the next harvesting operation.
Timber exploitation in tropical forests was initially highly selective and based on a combination of animal-powered extraction and transport by river. Where such systems have persisted, as is the case e.g. in many parts of Myanmar, they will have been largely compatible with the conservation of ecological values and genetic resources. However the increasing, global use of heavy mechanical equipment, more demanding in the intensity and width of road construction, and more severely damaging to regeneration and the soil, has had very severe impacts on the sustainability and functioning of the forest ecosystem. Although the effects of intensive logging, and the associated environmental damage, may be less discriminating in their de facto impact on genetic resources than highly selective harvesting and silvicultural “refinement” operations, they tend to revert the forest to a less species-rich phase corresponding to the earlier stages of ecological succession. This effect is made worse by the severe compaction of the soil resulting from the careless use of heavy equipment, which may leave substantial areas of bare hardened and eroded surface hostile to seedling development. Coupled with the harvesting of a larger number of species, as for example in the dipterocarp forests in Malaysia, Indonesia and the Philippines, where the ease of grouping of species by timber quality has increased market opportunities, the logging damage has sometimes been so severe that both advance growth and seedling regeneration of desirable species were virtually eliminated (Masson 1983). Since most dipterocarp seedlings do not develop readily on bare exposed soil the effect of intensive logging, where up to 40 per cent of the area might be bared by careless operation of heavy equipment, was to lose nearly half the potential regeneration.
The intensity of timber harvesting also determines the degree of canopy opening, which has strong influence on the successful development and composition of the regeneration. Large gaps in the canopy favour pioneer species while low intensity selective logging more closely mimics the natural processes of forest dynamics and scarcely alters the species composition (Whitmore 1990). However too frequent repetition of harvesting even on a light selective system may adversely affect the breeding populations of the slower-growing species if the number of mature reproductive individuals which are present before the subsequent felling cycle is severely reduced. Repeated, intensive logging at short intervals may eliminate species characteristic of late-stage mature-phase and climax forest and is liable to produce a combination of fast-growing pioneer species of low timber value with masses of climber tangles and areas of bare soil. Such a mosaic of cleared areas and low perennial weed growth may be invaded by fire, particularly in semi-deciduous and monsoon forests, with catastrophic effects on the regeneration of most timber species and their genetic variation.
The constraints on investment in forest management referred to earlier have led to increasing reliance on the logging operation as the principal means of influencing forest composition, structure and development, rather than the (expensive) thinning and refinement operations of the more complex silvicultural systems. Even when silvicultural operations are carried out after logging their effectiveness is determined largely by the state of the canopy, soil and regeneration left by the exploitation. Skilful and responsible harvesting, undertaken with understanding of ecological principles in forest dynamics, can itself serve silvicultural and conservation objectives. However all too often such aspects are entirely disregarded by logging personnel paid on a task or output basis and concerned to maximise rates of extraction regardless of the effect on the forest and the site. Further damage may be done by repeated harvesting without allowing sufficient time for recovery and regeneration. This has happened where market demand has arisen for species considered uneconomic at the time of the initial selective logging, and concessionaires have been allowed to re-enter the forest, regardless of the impact on the regrowth.
Failure to adjust the harvesting operation to meet long-term management and silvicultural objectives is the greatest and most dangerous weakness in existing attempts at tropical forest management (FAO 1989c). Conversely the development of a productive partnership between the timber operators and the forest managers is the most essential component of a management and conservation strategy. Without this the possibilities for the conservation of genetic resources in production forests must be severely limited and restricted to accidental residual populations.
Recent studies (Kerruish 1983; Jonkers 1987; FAO 1989b; FAO 1989c; FAO 1992a: Jonsson and Lindgren 1990) show that much of the damage caused during exploitation could be readily avoided at little if any additional cost. Although the choice of equipment is important, as powerful tractors and cable extraction systems can both cause severe damage, it is above all the lack of planning, training, supervision and appropriate incentives to the proper use of equipment which are responsible for most damage. Some studies in Sarawak have shown that the introduction of orderly logging reduced the area of forest severely damaged by 44% and at the same time effected a saving of 20% in the logging costs. Similarly in Surinam damage from skidding operations was reduced by 40% in properly controlled logging, while overall productivity was improved by 20% (Jonsson and Lindgren 1990).
The amount of damage is broadly related to the number of trees felled rather than the total volume of timber extracted (Whitmore 1990). Insofar as the effect on the advance regeneration is accidental it tends to be distributed over all tree species in an essentially random way, so that in terms of impact on the genetic resources it is unselective (Johns 1988). However the impact on species already rare and subject to selective logging will be potentially severe, if the future breeding populations are thereby further reduced. The seedlings of shade tolerant species, which depend for successful regeneration on survival for long periods under the forest canopy rather than rapid colonisation of gaps or sprouting from seed banks dormant in the soil, are particularly vulnerable to damage by heavy logging equipment. This compounds the adverse impacts on such species from extensive and sudden canopy opening. Since it is the heavy-seeded climax species which are most often dependent on animal seed dispersal the extent to which logging disrupts animal populations may also further affect these timber species. Stock mapping, timber marking, regeneration surveys and operator training, allied to careful planning of road making and logging operations, could be designed to conserve selected species and populations. Some studies have also indicated that quite small areas of logged forest within or adjoining logging concessions may be critically important to the survival within the area of keystone animal species (Johns 1989).
Although the determination of the influence of different logging practices and intensities on the species composition and genetic resources in the forest requires ecological and autecological research there is no doubt that the degree of care exercised in the harvesting operation has the most profound influence on the future options open to management and conservation actions. The nature of the changes needed to control and provide incentives for responsible logging is clear in terms of the length and nature of timber concession agreements, levels of stumpage fees and so forth. Equally important is the interest and involvement of local communities in and around the forest, whose activities in the wake of logging operations providing increased access to the forest can strongly affect subsequent regeneration.
The importance of the many non-timber forest products extracted from natural tropical forests is now widely recognised. The term now current for such products, NTFP, generally embraces all materials of a biological origin excepting timber which is being extracted on an industrial scale. The range of products includes foods, spices, medicines, fodder, essential oils, resins, gums, latexes, tannins, dyes, rattan, bamboo, fibres, a great variety of animal products and ornamental plants. Food and fodder sources in the natural forest are particularly important as dietary supplements, to reinforce seasonally dependent agricultural systems, and in times of drought or other emergency conditions (FAO 1989d). They often represent the highest evidence of value of the forest as forest in the eyes of the local people, and are therefore an important factor in the conservation of the total resources of the forest, including its genetic diversity.
The NTFP may also represent a major source of economic benefit in the national economy. Because those products which are used locally, very often the major component of NTFP, do not enter the market in which traded values are recorded, it is difficult to quantify properly their actual or potential value and therefore this is certainly greatly underrated. The potential value of future products which it may be assumed remain to be identified in tropical rain forests, for example possible pharmaceutical or cosmetic products, is often invoked in the context of the option values of biological diversity. However even without allowing for such possible future additional benefits the actual quantified value of NTFP is very significant. Southeast Asian sources probably account for most of the several billion dollars in annual world trade in NTFP (de Beer and McDermott 1989). Available estimates of export values indicate that the total figure for Indonesia alone in 1987 was at least US$238 million. Probably US$100 million of this figure relates to rattan, of which Indonesia supplies 90% of the world demand. However deforestation and forest exploitation are eroding the resource base and it has been estimated that about one third of the rattan species in Malaysia and Indonesia are under threat of extinction (Dransfield 1987).
Characteristic attributes of NTFP include their great variety and relatively high value per unit weight or volume, as compared with most tropical timber. Their harvesting is more labour-intensive and requires relatively little capital investment. Although the yield per unit area of forest is usually low it can be, in the case of some such products, harvested annually on a sustainable basis, with little or no disturbance to the soil or ecological functioning of the forest. Often the maintenance of a forest canopy is a necessary condition for the production of NTFP and therefore the possibilities exist for the simultaneous development of both timber and non-timber resources, with the latter providing an earlier economic return and a continuous source of income for local populations while the timber crop is coming to maturity. Selective logging can have a positive effect on some NTFP, such as rattan and edible fungi. Rattan grows best in gaps in the canopy, which can result from selective timber extraction.
Insofar as the conservation of biological diversity and genetic resources of the tropical forests is dependent on systems of management that mimic as closely as possible the natural ecological conditions and processes, rather than drastic alteration of the forest condition through intensive timber exploitation or clear-felling, the simultaneous harvesting of NTFP may therefore be important in bearing the costs of conservation within production reserves. However it will be essential to undertake adequate inventories of the non-timber resources, in association with normal forest inventories, and to specify precise objectives in the management of each area of forest. The degree of precision needed in assessing the NTFP resources may be determined by the level and methods of harvesting proposed. If the products are to be gathered by local people freely and informally the level of information needed will relate principally to the regeneration and sustainability of the resource and qualitative assessments may be sufficient (see also Ghana case study).
The interest in NTFP in the context of in situ conservation of forest genetic resources is therefore twofold - for their contribution to the feasibility of the conservation and management of forest resources; and for their genetic resources and their intrinsic value as components of the genetic diversity of the ecosystem. This implies the need to develop systems of multiple-use management of the forest (FAO 1984; FAO 1985a). Forest trees producing edible fruits or other products are frequently distributed widely but at low density per hectare and special attention may be needed to maintain viable breeding populations. Moreover they are likely to be involved in food-web systems, whereby seed dispersers or pollinators of other tree species may be dependent on food supplies from the fruit-bearing species. Conversely important fruit trees, such as the Brazil nut (Bertholettia excelsa) have known dependencies for their satisfactory pollination on certain large nectar-gathering bees which in turn are dependent for successful mating behaviour on wild orchid species. The loss or scarcity of orchids thus threatens the fruit production of Brazil nut trees (Prance 1985).
Management for timber production as the primary objective should be planned to be compatible to the greatest extent possible with the production of NTFP (FAO 1989b). This implies not only a wider information base from broadly based forest inventories but also much more complete understanding of the forest dynamics. High hopes have been raised for the future of so-called Extractive Management Reserves in the Brazilian Amazon, based on a range of NTFP resources, of which the best established are rubber and Brazil nuts. The range of products already identified is certainly large and some studies have indicated a-high commercial potential (Peters et al 1989). However there are considerable uncertainties over the replicability and sustainability of extractive management systems and some recent studies indicate that careful selective extraction of timber is likely to be a necessary component of overall management to secure sufficient levels of income from the forest. While the development of NTFP resources may have positive impacts on the conservation of genetic resources in a wider sense, the production of NTFP and of timber is not necessarily always fully compatible. Favouring NTFP can, at times, lead to a marked decrease in levels of timber harvesting, at least in the short term, since many timber trees are also sources of fruits or other extractives; the cultivation of some high value products such as cardamom (Elettaria cardamom) in the forest may hinder the establishment of regeneration of timber species in these areas (FAO 1984); etc.
Nevertheless the possibilities for different systems of multiple use of natural forests are of undoubtedly high potential in terms of their contribution to conservation of ecosystems and the in situ conservation of genetic resources of a variety of species. While it may be difficult and, in some cases at least, impossible to combine the different management objectives on the same limited area of forest, with the same intensity of timber harvest, canopy opening and population refinement, different working circles within the same forest may be used to maintain a mosaic of different ecological stages or conditions. In some cases working circles may overlap and in others they must be kept geographically separate. Such zonation is also compatible with the development of “buffer zones” around the forest, and “core zones” devoted to strict protection. This is dependent on high levels and intensity of management (see also the India case study in Part II).
Very little tropical forest is truly virgin forest in the sense of never having been inhabited by man (Webb 1982). Most areas have been subject to forest clearance and cultivation and are now composed of a mosaic of patches in varying stages of development towards the “climax” condition. A Nigerian forest described by Jones (1955–56) had apparently not reached a steady state after about 250 years (Whitmore 1991). In some areas, particularly where clearance was very extensive and prolonged by repeated fires, the species composition of the vegetation has suffered a major change, for example to a derived savanna woodland, or even grassland, possibly maintained by grazing and browsing as well as occasional burning. However in the absence of such repeated destruction of the regeneration, tropical forests show considerable resilience in recovery after clearance. On the other hand, unless given areas are allowed to remain as, and return to, the mature-phase (climax) forest, the genetic resources of species characteristic of this phase may become threatened due to the long timescale needed to reach it. The establishment of forest reserves to be managed for timber production, to the exclusion of traditional shifting cultivation, was initially a safeguard against such a danger. This has been compromised by the increased intensity of timber exploitation and the widespread failure to apply adequate harvesting controls and lack of subsequent management interventions to ensure effective regeneration in harvested forests. At the same time increasing encroachment or illegal logging which have reduced at least parts of the forest in many (most) tropical countries to a very degraded condition. As the increasing human populations put more pressure on the scarce resources of fertile land the threat to the remaining forests has continued to increase (see also India case study).
Recent reviews of forest management recognise that activities must take full account of the needs of the rural communities and that no attempted management system can be sustainable without the broad approval of local people in both planning and implementation (FAO 1989b; FAO 1989c; FAO 1992a). Such approval is unlikely to be achieved without the provision of some tangible benefits in the short as well as the longer term. As long as the perceived benefits of logging are that it allows access to the forest for illegal farming and theft of timber, particularly the undersized stems and advance growth of valuable species left as a result of selection felling to girth or diameter limits, the combined effects of the legal exploitation and subsequent depredations must be increasingly damaging to the genetic resources of valuable species. However the incorporation of extractive management of NTFP, together with the development of small scale rural enterprises based on the selective extraction of timber, could provide local employment and income. Increased participation of local people, combined with less intensive logging regimes, could then help to conserve a wider spectrum of genetic diversity in situ. However the fundamental requirement is the full endorsement by the local population that the land should remain permanently under forest.
Such theoretical models of the positive involvement of local communities in fully participatory management of production forests on a sustainable basis are still at only a planning or pilot stage in a few countries. The OEPF (Organisation de Ejidos Productores Forestales) project in Quintana Roo, on the Yucatan peninsular in Mexico, has been cited as an example of the involvement of local communities in the management of timber production forests, formerly under concessions to logging companies. Here the communities (ejidos) are directly involved in all aspects of forest management and share in the profits generated through the sale of forest products. A high level of local support for the forest management is reported, related to the provision of employment and income (WWF 1991). However technical problems related to the regeneration and other silvicultural aspects of the project are also reported to require substantial external assistance (WRI 1991).
Following earlier reviews of possible approaches to multiple-use forest management in India and in Ghana (FAO 1985a) new initiatives are now under way in both countries, including elements of both the involvement of local people and the conservation of biological diversity and genetic resources. In the Western Ghat forests in southern India draft proposals for multiple-use management are based on the zonation of the forest and surrounding land into five management zones, of which the central zone (Zone I) is to be dedicated principally to the conservation of biological diversity and genetic resources. This approach reflects principles recognised in the “buffer zone” concept (Sayer 1991) as well as the participatory approach of social and community forestry schemes.
Another example of ways in which local people, particularly those long settled or indigenous to the area, can have positive impacts in the conservation of the forest and its genetic resources is through the use of local knowledge in taxonomic, ecological and phenological studies. Such studies are essential to the adequate understanding of forest dynamics for conservation objectives. With appropriate orientation to the lines of scientific research needed and some training in the categories of information required, the intimate knowledge of the forest and of many of the species which is often held by local people provides a valuable basis for taxonomic and ecological studies. Many tropical botanists can testify to the skill and value of local “tree finders” in taxonomic and ecological studies in all tropical regions.
The scale of the data collection needed, even for a small selection of the many thousand species present in most tropical forests, is out of all proportion to the scientific manpower and financial resources available within each country and internationally. An interesting example is the use of so-called “para-taxonomists” in the current programme for a national inventory of biological diversity in Costa Rica. This is under the overall direction of the Costa Rican National Biodiversity Institute (INBIO) which initiated the programme in 1989 with the joint objectives of conservation and the exploration of potentially valuable organisms. Data from new collections is brought together with earlier information in a computerised database which can provide information on important aspects of a species' biology and autecology linked to taxonomic identifications. The mounting of intensive short courses in “para-taxonomy” has transformed the rate of collection and subsequent specialist identification of arthropod species. In addition to the value of the information and material collected this approach can provide an important link between the local communities and the forest managers (Tangley 1990). In the programme in Costa Rica, in contrast to the situation in many African and Asian countries, the local population is not indigenous to the region and lacks the long history of forest use still found in most other areas in Central and South America. The involvement of the para-taxonomists provides a link between the communities and the better understanding of the natural resources of the country. Since the most damaging impacts on the natural forests came from immigrant populations and technologies this improved understanding through involvement in gathering data on the biological diversity has both direct and indirect benefits.