The main aim of any sustainable forest management plan should be to produce a plan for resource use that is acceptable to all affected stakeholders (including taking into account the interests of future generations) and avoids irreversible choices. In theory, the production of a forest management plan includes the following three key stages:
_ Analysis of the forest and its environment: including: the legislative and regulatory context (e.g. land use planning and regulations); historical and human situation (e.g. social needs and cultural aspects); socio-economic assessment (e.g. economic needs, infrastructure requirements and market developments); assessment of the natural environment (e.g. fauna and flora in forest stands); and the technical options envisaged (e.g. family/community felling, intensity of harvesting and replanting activities).
_ Production of a clear statement of management priorities and activities: including: a hierarchy of production objectives; suggested forest zonation; approved choice of technical options; statement of planned treatments (e.g. schedule of harvesting and silvicultural activities); and a social, economic and environmental justification for the decisions taken.
_ Establishment of a follow-up assessment and monitoring mechanism: that will measure performance against each of the objectives set in the plan and allow the periodic revision or updating of the management plan if necessary.
The design of a forest management plan should integrate at least four types of information in its content: social, political and cultural factors; physical, biological and ecological factors; financial and economic factors; and technical elements (e.g. possibilities for silviculture, harvesting and processing). In order to ensure forest survival, forest management should also satisfy local people's requirements for land and forest products. Knowledge of the forest ecosystem, its evolution, potential and development options will be useless without an in-depth analysis of related agricultural, political and social factors.
It must always be borne in mind that tropical forests are complex and still relatively unknown ecosystems located in areas that are very diverse in terms of their socio-economic structures. Attempts to try and simplify the complex relationships within these ecosystems and between these ecosystems and surrounding human populations, have largely failed in the past. It is important therefore, to be realistic and adopt a flexible approach to forest management that is suitable at the many different levels of management (i.e. local, regional and national) and to realise that there is unlikely to be any universal methodology that can be applied in all cases.
To be sustainable, forest planning and management should aim for appropriate development of all natural resources (including: water; soil; plantlife and wildlife) while, at the same time, maintaining the health and vitality of forest ecosystems.
With the right management, forests can produce a range of services and products (wood and non-wood forest products) in a way that is sustainable. Conservation and improvement of the protection functions of forests should also be encouraged in a forest management plan.
Periodic assessment of the status and condition of forest resources should be ensured in a permanent and continuous manner. This should take into account both biotic and abiotic factors that can have an impact on the vitality of forest ecosystems (e.g. parasites, overgrazing, fire, climate change and pollution). Management plans should consider all resources, users and ownership rights and should be periodically updated. They should define the resources and methods needed to minimise the risk of forest degradation and should seek to rehabilitate previously degraded ecosystems. They should be based on consultation and exchange of information among all the various stakeholders affected by the plan.
Activities should aim for a quantitative and qualitative balance in growth and extraction by minimising direct and indirect damage to the resource. Regeneration, harvesting and maintenance activities should be programmed in space and time in order not to reduce the site's productive capacity. Infrastructure should be planned so that it minimises negative impacts on the environment. Silvicultural treatments should promote structural diversity in forest stands and encourage natural regeneration. Afforestation of fallow or deforested land should be considered a priority each time there is a possibility to increase economic, ecological, social and cultural values from such activities. Afforestation should rely on species and silvicultural methods that are appropriate for each site. Appropriate measures should be taken to balance the pressures of livestock herds and grazing on forest regeneration and growth, as well as on biodiversity.
Tropical forest research has come in for criticism because it is (or has been perceived in the past as being) remote from reality. Nevertheless, many experimental activities have been pursued in the tropics, particularly in the very practical area of the evolution and dynamics of forest stands subject to human intervention (usually after harvesting). Yet much remains to be done. For example, the growth characteristics of high value species, such as Meliacea, Swietenia macrophylla and Cedrela odorata in tropical South and Central America, are still largely unknown. This makes it difficult to manage them sustainably, because of a lack of information about how to obtain sufficient regeneration.
A lack of staff trained to produce and implement sustainable forest management plans is also part of the problem. To find a way around this obstacle, field researchers are convinced that the best training for forest managers of the future can be obtained if they spend some time working in forest research.
Certain forest management tools still need to be refined, including: field inventory techniques; tele-detection and geographical information systems; the use of sample plots to monitor forest stands; and activities that increase the quality and value of standing wood. Finally, it is important to have easily useable and updated forest resource databases to enable rational resource management decisions to be taken.
Forest harvesting plans should be produced at least one year before field operations in order to avoid tractors rambling in search of trees to fell. Production of these should include inventory operations to single out trees to be harvested and planning of main and secondary road and skid trail networks. Compliance with the plan should form an essential part of monitoring by the forest authorities. Maintenance and drainage work on roads, respect for maximum slope gradients for skidding tracks and stocking and transport areas, should be obligatory. While difficult to enforce, another essential measure is to employ suitably sized cutting machinery (oversized machinery leads to many problems such as soil compaction). Strips of forest along riverbanks should be kept in good condition in order to maintain water quality and to provide habitats for plants and wildlife.
The vitality of natural regeneration affects the way that harvested stands renew themselves and harvesting disturbances can have a negative effect on the rest of the stand. In the first place, the stand is destabilised by the increased mortality of young trees. If more than one third of the stand is opened up, short-lived and invasive pioneer species may also become established to the detriment of species with structural, biological and/or commercial value. In some cases, after two to three years mortality may drop, but it generally remains higher than in untouched stands.
Recruitment of young trees and the growth of medium-sized trees (i.e. the next commercial crop) are stimulated over periods of, for example, ten years. It is suggested that the cutting cycle should generally be proportional to the extraction intensity (e.g. 20 years for a harvesting intensity of 5 m3/ha to 15 m3/ha, but 50 years or more for harvesting in excess of 25 m3/ha.
Regeneration should preferably be promoted through the application of traditional silvicultural treatments. Short rotation (20 to 30 years) selection systems can only be applied within stands rich in species and under conditions where overabundant large-sized and/or less valuable trees are also removed as non-commercial thinnings. Otherwise, longer cutting cycles (e.g. about 50 years) should be employed. The lowest acceptable limit for harvesting diameter will depend on forest structure and composition (as well as other factors such as markets or processing possibilities) and no standard recommendation is valid. In all instances, not more than 30% of the total forest area should be affected by harvesting operations, in order to avoid irreversible stand destruction.
The systematic improvement of forest stands by non-commercial thinning of less valuable tree species can be justified within homogeneous and rich forests, but should be avoided in poorer stands where treatments cannot be economically justified because of their high costs. In the latter case, it may be best to envisage only selective clearing confined to the areas right next to the trees to be promoted. Treatments must be planned with the intention of helping to conserve biological diversity. Moreover, it should be emphasised that, in the framework of management, clearing work should preferably not be entrusted to a concessionaire but instead to a "practising professional" forest service.
This silvicultural treatment is usually applied to natural stands that are poor in commercial species. Enrichment planting entails complementing the stocking of currently commercial species by planting seedlings (usually 3-4 metres apart) of valuable species, adaptable to the site, in parallel rows (20-30-metre apart) in the forest. This method has been used all over the world (sometimes successfully) over relatively modest but well monitored areas. Enrichment has the merit of preserving the natural forest intact without disturbing it too much but there are also inconvenient aspects to this approach, including: the difficulty of controlling such activities; the long-term planning required for such treatments, and the high labour and other costs of continuously carrying-out such activities.
This activity involves felling and replanting degraded forest stands of low productivity. Methods vary in intensity in line with the availability of resources and management objectives. The following aspects of such activities have to be taken into consideration: the suitability of the site and the reforestation technique that will be used; the utilisation of high-performance plant material; the maintenance of young plantations; the behaviour of artificial stands (e.g. the need for clearing and pruning); protection and plant health issues; and the technical quality of the wood that will be produced. In an attempt to reduce the destruction of standing and remaining vegetation, one version of this approach is to open two to three metre wide strips or transects in the forest in parallel rows several meters apart (depending on the species). As the planted seedlings grow in response to the need for more direct sunlight, the canopy is then opened progressively until the plantation exceeds the height of the remaining surrounding vegetation.
Cost considerations are important when choosing amongst all of the various plantation establishment options. For example, different methods can be used to convert degraded natural forests to plantations, such as: manual methods; mechanised methods; or a mix of reforestation and agricultural activities. However, the choice that is made has to consider ecological, economic, sociological and technical criteria. Manual methods usually imply having to utilise a considerably large labour force, which is not always available at the right moment. Therefore, the need to reforest large degraded forest areas often requires the use of mechanisation for certain tasks.
There are many problems associated with very large intensive monoculture plantations, which are especially difficult to manage in terms of their logistical requirements. Mixed species plantations also lead to more variability in the structure and composition of planted forests.
Half of the world's livestock (e.g. camels, goats, sheep and zebu) lives in dry zones. Management of forests in such areas should take this into account and the practice of agro-silvo-pastoral systems would, therefore, appear to be most appropriate for the sustainable management of these areas.
Measures to protect and restore the soil are essential, particularly in dryland areas prone to desertification. Forest production is only one aspect of agro-silvo-pastoral management, encompassing the production of wood, forage, fruit, etc.
Regulations to balance the utilisation of dryland forests by livestock with their productive capacity is essential and pasture management is a key element of integrated management of dryland forests. For example, there has to be equilibrium between tree and grass layers. Rangeland management should help to combat overgrowth and to maintain silvo-pastoral potential and livestock pressure should be adapted to forage stocks in both time and space.
Fire represents a key element in dryland forest management. Controlled burning at the beginning of the dry season is preferred to late seasonal fires, in order to promote the dynamics of wooded and grass vegetation. Given the context in which many of these forests are used (particularly in Africa), it is vital not to overlook the essential role of women in training and extension.
Silviculture should take into account the constraints placed on dryland forest management by physical, biological and social circumstances (e.g. the prevalence of drought and brush fires, extensive ranching, transhumance, etc.). Natural regeneration using techniques such as coppicing and/or the use of root suckers should be encouraged because the poor the water regime will lead to a natural advantage of vegetative reproduction over natural sexual reproduction. As a guide to which technique to employ, the forester should copy nature's examples and use sexual reproduction in favourable environmental conditions, or runners, coppicing and layering, in areas exposed to severe hydrological stress.
Enrichment is possible, and will have many of the same advantages as it does in humid tropical forests, but with one further drawback: it will increase potential vulnerability to fire passage even if fires are of a low intensity. Fire should be confined to open forest formations or tree or shrub savannahs, which are characterised by enough rainfall (at least 800 mm throughout the year) and where adequate maintenance and protection can be ensured.
Measures to protect fruit and forage species should be taken, such as control over pruning and stripping. In coppicing, the minimum-harvesting diameter should be between 6-8 cm, depending on the species. Rotation could be as short as 7 years to 14 years. The height at which trees can be harvested again will depend on the species. For industrial roundwood production, the minimum harvesting diameter will be between 30-35 cm, with rotations of about 20 years to 40 years or, in some cases, as much as between 50 years to 60 years.
Given their special nature, management of mangroves depends on the management of surrounding areas and, in particular, measures that affect and modify hydrological and coastal cycles and functions.
In view of this, the harvesting of forest products should be compatible with the other production functions of this ecosystem (e.g. game, fish, crustaceans, molluscs, apiculture and salt) and with protection functions (e.g. wildlife, plants and biodiversity). A minimum harvesting diameter of 15-18 cm should be used to maintain production and conservation functions in mangroves. The rotation period should be at least 10 years, but this will depend upon the species.
During harvesting, particular care should be taken in order to minimise damage to the soil and, at the same time, ensure natural regeneration. Seed bearing trees should be conserved if they are considered insufficient in the forest (i.e. less than 2,500 stems/ha of more than 30 cm in height). In the absence of natural regeneration, establishing plantations may be an appropriate option. Primary and secondary canals should be used to extract products and these should be carefully maintained. New canals should be less than 1.5 m in depth in order to limit soil degradation and erosion.
In protected areas, two main management activities should be given priority:
_ identifying and managing areas that represent a variety of different ecological zones; and
_ updating management plans on the one hand to achieve the objectives of maintaining biological diversity and on the other to best develop other uses of the resource, such as: hunting; wildlife viewing; ecotourism; and recreation.
