Abstract

1For thousands of years, Man has exploited resources and to some extent controlled the rate of their renewal for activities such as crop and livestock production. However, human intervention remains limited in many areas where resource renewal depends on extraction pressure and natural bio-ecological processes, for example, in the case of fishing, water or plant resources. This publication explores the limitations and conditions that effect natural resource renewal in intertropical regions. The first part of the publication examines these limitations which depend primarily on Man's impact, which can be voluntary or involuntary, direct or indirect.

2Tropical forests provide good examples for analysing the temporal limitations of renewable resources. The rate of renewal is compatible with the rate of exploitation for some but not all resources. Some species seem to be nonrenewable (or at least not renewed), whereas the forest, in its entirety, should be considered as either renewable or nonrenewable depending on the real definition of the term forest. Thus, extractive operations in the Amazonian forest should not be considered as synonymous with the exploitation and plundering of resources nor as an intrinsically appropriate means of reconciling conservation and forest development. Everything depends on the bio-ecological and demographic characteristics of the species being exploited which, although essential, are largely unknown parameters. This does not just apply to tropical forest resources. These parameters determine not only the productive capacity of different species but also how they are exploited and, therefore, whether or not development models are relevant. Here, emphasis is put on the diversity of the Systems for exploiting forest resources and the multiplicity of socioeconomic Systems that this diversity allows.

3There is an analysis of several Indonesian examples where ecosystems are manipulated and forest species domesticated. It shows that different social groups perceive things differently and how politicians use this disparity in the context of forestry.

4A case study of indigenous agroforestry management illustrates how farmers have successfully adapted forestry resources to agricultural Systems, and above all, actually transferred forest structures from "nature" to agriculture. The transfer process is presented as an original strategy to appropriate from nature. It combines classic plant domestication techniques and an attempt to domesticate an entire ecosystem. Using this example, it is possible to re-evaluate the academic distinction made between natural, modified by Man, and artificial in the general context of relationships between societies and environments. This is far removed from the linear concept of the domestication process which goes from a wild species to a cloned tree and from a "natural" ecosystem to a controlled orchard monoculture.

5Tropical forests are seen either as an unproductive "green hell" or biodiversity's paradise lost. In the case of mangrove forests, these Manichean perceptions can be added to the equally distinct perceptions of wetlands.

6In general, mangroves are considered to be fragile ecosystems that appear to be irreversibly affected by human activity. Statistics suggest that mangroves are receding on a global level. However, different conclusions can be drawn from a comparison of the State of mangroves at different periods. Our appraisal shows that the situation varies from one country to another depending on the disciplines concerned (natural or social sciences). Even the definition of mangrove is problematic. The opposing notions of fragility and robustness, stability and instability are examined in the context of mangroves. The analysis of processes of change, the identification of stakeholders, the consideration of contradictory political, economic, and social interests show the need for a pluridisciplinary approach to understanding the dynamics of mangroves. In this way, the interactions between mangroves and society can be considered on different temporal and spatial scales.

7In savannah regions, the rhythm of contrasting seasons is reminiscent of environments with a rapid "turn-over". However, a careful examination of plant resources shows that this is not the case and that the management constraints that exist in savannah regions are in fact no different from those in forest areas. Here again, the diversity of use and human activities are determining factors in terms of the capacities of resource renewal.

8In African savannah regions—which supported the world's richest communities of large mammals despite being renowned for their poor soils—there are many species of Gramineae with characteristics and properties of varying importance and use.

9In western Burkina Faso, the perennial grass Andropogon gayanus is a remarkable indicator of the impact of the intensification of human activities. According to different observers, it is a forage plant (herdsman), an indicator of fallow land ready for recultivating (farmer), a raw material for making straw objects (various inhabitants), and an indicator of a "natural" environment (the passer-by). The scientist shows that its presence is the result of a modification of the natural environment linked to successions that follow cultivation. The species reaches its peak between 10-20 years after land has been abandoned. Thus, it benefits from first degree modification which makes it distinct from natural flora (Andropogon chinensis) that declines in a modified environment. It is only when the cropfallow cycle accelerates (second degree modification) that A. gayanus' continued presence is threatened. Further modification, with an even shorter cycle (third degree), encourages some people (mainly West African migrants) to behave in a protective way which could be described as artificialization.

10The evolution of agrarian Systems in Burkina Faso shows that the environment is now being transformed rapidly because agriculture has become part of the market economy. The main production objective is no longer self-sufficiency but clearing saleable produce. In this new context, the most important part of System management eludes the farmer.

11In Burkina Faso, land occupied by farmers of West African origin tends to be in the form of agroforestry plots, where Butyrospermum paradoxum is the dominant species. Once established, B. paradoxum benefits indirectly from cultivation practices, ie from certain factors related to the modification of the natural environment. This is not contradictory with the overall ageing of the B. paradoxum population. The actual frequency of this tree—which is rare in natural dry forest areas—is due to the disappearance of traditional practices and to a marked preference over other species including Faidherbia albida, which is favoured by other farming communities.

12A parallel can be drawn with plots of F. albida which also age and decline in different circumstances. There is an examination of the socioeconomic causes and the ecological impact of this scarceness of tree resources.

13An agronomic interpretation of types of environmental modification and artificialization is useful for plant resource management. The study of species used in the Sudan-type savannahs of West Africa—which are a threatened resource, eg. B. paradoxum and A. gayanus—reveals that there is a hierarchy in the control or "degree of artificialization" of the resource. The analysis is based on the observed practices and objectives. Several degrees of artificialization of the resource species can be identified: regulated exploitation, assistance/protection, elementary crop, and semi-natural crop. This type of classification—which complements the classic concepts of natural and cultivated conditions and puts them into perspective—should be incorporated in the design of development support programmes and environmental management plans. We show that local biological resource management does not use nature's full potential. "Native resource species", which have the advantage of being ecologically and culturally integrated, could be developed. This would provide better protection for them than laws or nature reserves.

14The second part of the publication covers the social management of renewable resources on a local level.

15The way researchers view the relationships between societies and renewable resources has changed considerably over the years. Initially, the social context was considered to be one of many factors influencing resource use. Social practices were seen, above all, in terms of how they were adapted to resource dynamics, which were perceived as the central problem. Social factors were then considered in relation to other aspects, for example modification/artificialization and decisionmaking, while the issues concerning resource management were linked to how these societies function. In some ways, the social organization of resource use leads to wider topical discussions about development.

16In Madagascar, research into deforestation is a priority. For the last few years, the different approaches to the environment—ranging from a naturalist approach to one that takes account of economies and societies—have been called into question. In the southwestern part of the island, a social approach to the phenomena of deforestation has been adopted because it makes it possible to identify situation types—that emerge on a regional level despite the diversity of local situations—and to evaluate the role of migrants and indigenous populations, respectively.

17Migration is not a new phenomenon in Madagascar but began in the 1920s. Nonetheless, migratory dynamics and patterns, the way migrant populations settle and how long for have changed considerably. The combination of social, historical and climatic factors has meant that migrant populations have gradually become communities which are permanent, in some cases. The main consequence of these modifications has been the emergence of social and land-related conflicts between indigenous and migrant populations. These are increasingly serious and cause almost irreversible damage to the forest environment. There seem to be two causes for this. Firstly, local power is being eroded in most regions while migrant solidarity is growing. Secondly, the means used by migrants to settle are more and more inaccessible to local groups who have lost ceremonial control of access to the forest. In many parts of southwestern Madagascar, migrants are now organizing migrations for their parents or relatives (as well as for different ethnic groups) and it is they who control access to the forest to some extent.

18In the ancient sakalava society of the west coast of Madagascar, where population density was extremely low, access to natural resources was arbitrated by "land masters" (tompontany) who screened new arrivals and ensured that resources were used moderately. Throughout the 20^th century, migrations to Menabe meant that indigenous people from the west coast became a minority and gradually lost their status as tompontany. Extensive cattle rearing, once the main production System, was forced to make way for permanent cropland.

19The use and destruction of the forests in Menabe used to be moderate and brutal in turns. However, it has recently exceeded a critical threshold across vast tracts of land. The forest is burnt for maize cultivation which has become by far the most profitable way of farming. In addition, local production Systems have been jeopardized because population density puts too much pressure on land. The only way of maintaining them is to use the remaining forest. Today, it is no longer just the migrants—seeking to build up cattle numbers quickly because of their social status—who are responsible for deforestation. Now, the indigenous people from the west coast are also directly contributing to this ecological disaster. The internal crisis affecting their society has meant that they adopt "egotistic" strategies in the interest of the few and to the detriment of the group.

20The problems facing African forest resources are similar although slightly less extreme because of the current State of human pressure.

21In Kouilou (Southwest of the Democratic Republic of the Congo), the Vili people traditionally considered natural resources to be inexhaustible. However, their abundance depended on the State of the relationship between people and spirits. For the last few decades, people living in rural areas (the Vili and migrants from other regions) no longer just take resources for their own use but also to supply the town Pointe-Noire, which is constantly growing. The Vili people have noticed a decline in renewable resources, particularly fishing and hunting. They put this down to Man's environmental impact and the fact that the spirits are angry. However, since the political changes that occurred between 1989 and 1990, these beliefs set them apart from the migrants who have settled on their land.

22The fourth case study examines the role of water—a key resource vital for all human societies—in the extreme context of the Atacama Desert, Chile.

23The Acatama Desert is very rich in minerals and has several oases where small farming communities have developed survival techniques over generations. Throughout its 15 000-year history, Acatama society has had to cope with an extremely hostile geographical environment and a multitude of sociocultural attacks. The question is how has it succeeded in conserving its environment and cultural identity to this day? The answer can be found by examining: archaeology, history, the social function of modem communities, and an updated analysis of the main economic indicators of production. This gives a reasonably optimistic view of the future of the ethnic group's identity. The rural exodus does not seem to have been caused directly by a drop in the availability of water for agricultural use. It can be explained by a desire to be part of the modem world temporarily in order to benefit from the advantages offered by civilization. This is coupled with a sort of "hibernation", whereby land is entrusted to the elders for a short time. Now, some production Systems have been carefully adapted to urban markets in the region and there is real evidence to show that numerous customary rites have been preserved. Lastly, young people are returning to the land to improve the use of productive areas, all of which are further proof of an exceptional capacity to adapt.

24Deserts are rarely the focus of international concern despite the unique adaptive capacities of the species that inhabit them. On the other hand, tropical forests, and particularly the Amazon Basin, receive constant attention even though little importance is given to the complex practices used by forest communities to exploit resources.

25A case study of the management System for a specific forestry resource— damar resins in Sumatra, Indonesia—illustrates the changes that have occurred over the last 50 years. The study shows how complex the relationships are between the Systems of ownership, local economic structures, and social relationships on one hand and the ecological conditions and Systems of representation on the other. First, the study shows how the combination of specific economic and ecological factors has led to a total reorganization of the countryside and production Systems. Despite this evolution, the resources and ecosystem have remained more or less unchanged. There is then a description of the revolutionary impact that this reorganization has had on local institutional Systems. As a result of which a novel strategy for appropriating land/resources was implemented, granting individuals the right to manage the "resin" resource as part of an agroforestry System with a commercial objective. This has strengthened the collective institutions and helped preserve the common resources.

26The dynamics of domestication and the privatization of land and forestry resources do not seem to follow any logical pattern. The development of classic privatization laws can be seen in several examples where the forest has been transformed by agriculture. However, the forest resources or structures are integrated into the new farming Systems that are set up, which also adds a new dimension to collective rights.

27Natural resource management models which claim to be models for sustainable development are examined and discussed with reference to the creation of extractive reserves in Brazil. Thus, the extractive operations practised in the Amazonian forest can not be presented as an activity that is synonymous with the plundering of resources nor as a panacea that reconciles conservation with forest development. Extractive operations are multifaceted and depend as much on the economic pressure on resources as on the bioecological and demographic characteristics of the species being extracted. Taking account of these parameters and where they fit in terms of temporal and spatial scales is essential if there is to be an accurate environmental impact assessment of extraction and if development models are to be built. This contribution underlines the diversity of the Systems for exploiting forestry resources and the consequent multiplicity of socioeconomic activities.

28The problem of the social management of renewable natural resources is put in the context of the democratization of the institutions in Mali.

29In the central delta of Niger, the specific features of small-scale fishing—directly linked to the characteristics of the river water System—are manifest in terms of temporary and spatial organization. The sustainability of the production System depends on respecting these characteristics. This is illustrated by the production crises and the social disorganization observed in the 1970s and 1980s, when management decisions concerning resources were centralized and local producers were dispossessed. This overshadowed the benefits of previous local management.

30The current move to decentralize power has meant that farmers in rural areas (organized into districts) are being given back the power to manage their own resources. The agricultural model used is little adapted to production sectors that exploit renewable natural aquatic resources. Of course, it is based on the concept of local responsibility which has encouraged a spontaneous reorganization of the fishing industry. However, it does not take the ecological, social and territorial specificities of fishing nor the interactions between fishing and other production sectors—dependent on the same natural System—into account any more than the previous centralized policies. Fishermen still have limited jurisdiction over their fishing grounds and not enough consideration is given to safeguarding their interests.

31The third and final part of the publication is entitled "science, decisions and strategies for development". The question of decisions incorporates the different points of view held by all those involved in resource management. Thus, the representation of the State of the resource (and the definition of the resource itself) refers explicitly to the nature of the decisionmakers.

32"Social demand" influences the orientation of scientific research. In return, researchers transform the questions that are put to them. Scientists, therefore, have an important role in providing knowledge that governs the relationships between societies and their environment. They control and, therefore, are responsible for the choice of data (and the assessment of information). They record information in the form of databases and make it available through the use of models that are designed to formulate and test hypotheses and even to propose recommendations.

33In the case of fallow land, the soil is a renewable resource at the same time as being the support for forage and fuel resources (bushes). In the Aymara community of the Bolivian Altiplano (Central Andes), the use and management of these resources can not simply be interpreted in terms of how they adapt to the environmental constraints even though these are considerable. Resource use and management also depend on other factors, particularly socioeconomic ones, which are the result of constant and dynamic interactions between individual and collective practices. Therefore, using a holistic approach, the future of fallow land should be considered in the context of agropastoral Systems where a collective rotation on some communal land is integrated with individual rotations.

34The cycle of a collective rotation is remarkably stable in the long term. However, over the last few years, pressure has been such that two breaks normally spread over 2 successive years are combined each time. This occurred in 1990 but did not recur until the end of the period of observation (1996). The modifications made to collective land management are the resuit of negotiations between farmers who also cultivate land independently.

35The community authorities decide on how much flexibility there should be for crop succession and the calendar (tillage and harvesting). This is discussed at assemblies which also provide the opportunity to discuss or contest other issues. This flexibility means that farmers can fit their individual strategies around the cropping plans that have been defined and established. Lastly, there is reference to the fact that the stability of standard practices depends not only on "material" needs but also on a series of cosmological and historical factors.

36In the fishing industry, both industrial and small-scale fishing units use a similar strategy, involving mechanisms that attract and hold shoals of large migratory deep sea fish for a few hours or days. The scientific analysis of this practice shows how the efficiency of this mechanism is directly linked to how decisions are made. The introduction of these mechanisms has had an impact which is manifest on many different levels: societies, fisheries, resources, ecosystems, etc. Therefore, a pluridisciplinary approach is needed for conducting an impact assessment. There is a discussion with three different examples (the Falkland Islands, Réunion, and Vanuatu). A grid is used to analyze the changes linked to the fish concentration mechanisms and to the capacity of the fishing Systems to evolve and adapt to their introduction. The mechanisms are considered as the meeting point between the behaviour of a resource and the decisions taken by the fishermen concerning resource exploitation and management. Priority is then given to the capacity of organizational learning and to how the institutions function.

37The case of Vanuatu is a good example of a programme that failed because it clashed with the village communities' organization and social rules. In the Falkland Islands, the number of fish caught in the concentration mechanisms varies from island to island where only a small proportion of fishermen specialize in this type of fishing. In Réunion, these mechanisms have been successful. They are still in use because professionals are involved in installing and managing them.

38In the next contribution, there is a multifactorial analysis (technotope) of the practices used by small-scale fishing units that operate along the coast of Guinea. There is a description of the species caught, the fishing grounds and the groups of fishermen that use them. The characteristics of the fishing zones are then analyzed in relation to the main characteristics of the fishing units. These different explanatory factors were used to put together an analytical representation of the differentiated exploitation of the fishing grounds (technotopes).

39Small-scale fishing practices in Senegal were the object of another modelling experiment which examines the process for individual decisionmaking—objective, choice, various criteria and method—from a cybernetic point of view. The modelling approach was chosen in the light of observations and the associated decisionmaking process. The different decisionmaking models developed during the exercise are discussed. The efficiency of the decisionmaking process—when it is considered as one of the agents' adaptive functions—seems to be linked to the time and the context in which it was carried out.

40To fully understand the relationships between marine resources and the characteristics of the marine environment a database is required. The choice of information and how to access it are important considerations for potential users.

41The different stages involved in the construction of a database are described in the context of a research programme on global changes and marine resources. Ail the meteorological data on oceans collected by merchant vessels since 1854 (over 100 million observations) have been grouped together, corrected and validated in the Comprehensive Ocean-Atmosphere Dataset (COADS). A research programme on the dynamics of deep sea species in the upwelling zones has, in fact, shown that numerous developing countries did not have access to data relating to their own coasts because of the complexity of coding and because they did not have the necessary extracting and processing equipment. The designers of COADS sought to develop an accessible and user-friendly way of extracting information needed for research.

42Before the general conclusion, there is an analysis of a multiagent simulation model designed to study the dynamics of a fishing resource in a tropical flood plain System. The model takes into account the main biological and physical characteristics of the river Niger in Mali, including: the heterogeneity of the aquatic environment, how it fragments and connects, the scale of annual flooding, the range of fish species and their reproductive cycles. A series of simulation experiments was conducted to compare how the fish populations reacted to different fishing scenarios. The results show that the annual catch is very dependent on the severity of recent flooding whereas it is not very sensitive to the size of actual or previous catches. This can be explained by the fact that the catches are largely made up of young fish. Nevertheless, it seems important to regulate fishing activities to avoid the danger of over-investing and overfishing which can reduce profitability and cause social conflicts. It also seems important for the managers to ensure that the quality of the ecosystem's structures is conserved so that annual fish production can remain high.