Search

André Aubréville was a remarkable figure in the field of forestry. In the 1920s, after training at the Nancy School of Forestry, he joined the colonial forestry service. His books reflect an encyclopaedic mind, clarity of thought and a visionary talent, and still serve as reference works. Realising that the future of tropical forests was under severe threat from human activities, he established forestry bodies that would work to ensure what is known today as sustainable forest production. In 1939, he was appointed Inspector-General of Water and Forests in French Equatorial Africa, but had already achieved renown as a botanist specialising in Sapotaceae and in biogeography. At the age of 60, he was appointed as a Professor at the National Museum of Natural History in Paris, and entered the Academy of Sciences of the Institut de France. He was an indefatigable worker who considered botany as a means to reach a better understanding of the complexity of tropical forests. He vigorously opposed ill-founded generalisations, showing how climate, past and present, determines the contours and the local composition of African forest flora, which was being severely harmed by wildfires whose devastating and long-lasting effects he was well aware of. He pioneered the “tropicalisation” of forestry techniques and was the first to demonstrate the inadequacy of the “primary” forests concept and to point to the potential of “secondary” forests. He had no doubt that timber would maintain its value against competing materials in the fifty years to come, and that the most sought-after tree species would remain so for their superior technical properties. In all of his work, he advocated a type of interventionism designed to prevent any form of over-exploitation of tropical for¬est resources. Some may discern an overly colonialist mindset, but in the sheer scope of his proposals in favour of forest protection, it is also possible to see a pioneering and visionary mind at work in the field

In the forested countries around the Gulf of Guinea, enrichment planting in dense forests with few naturally occurring commercial species began in the 1920s. It is clearly necessary to offset forest losses from logging by conducting silvicultural operations to reconstitute a forest's initial composition using suitable species. Such a strategy, which is sometimes strongly opposed but would convert wild forests into forests with greater potential value, can only be applied with a view to the long term. And this is only possible if the means provided to foresters are guaranteed over the long term. Enrichment planting is justified by the small number of commercial forest species, which will still be the same species in fifty years' time because they have the best technical properties. A for¬est enriched with okoumé, limbo and niangon to produce 50 or 60 commercially valuable trees per hectare will therefore always have more value than a wild for¬est. Enrichment is also justified by the increasing rarity of the most sought-after species, which cannot regenerate under dense cover. For example, we know that the abundance of okoumé in certain areas is the result of early human settlements that have since disappeared. Enrichment is also justified as a means of preventing logging from encroaching into the entire forest and gradually destroying it. Sawmills often decimate the forest surrounding them, and forest roads contribute to its fragmentation until crop fields take over the soil entirely. With no listing of protected forests and no silviculture, within just a few decades there would be no more economically viable forestry and no more forest industries manufacturing timber products for export. Abstract adapted by the editorial team.

Until 1935, tracts of virgin forest could still be seen when travelling along the roads of Côte d'Ivoire. Since then, with the un¬bridled expansion of coffee and rain-fed rice crops, runaway forest clearing has been the rule. Farmers fleeing the depre¬dations of the agouti, or of parasitic fam¬ily members, move away to clear more distant forests. By 1957, an expedition was needed to search for primary forests. A new road would destroy a forest within ten years, and loggers would only come through once. With the disappearance of Africa's dense humid forests, the dry sea¬son in its Sudano-Sahelian regions has grown longer. It is also important to map the areas of primary forest before they disappear altogether. The study presented here aimed to classify the vegetation of Côte d'Ivoire's forests on the basis of 12 transects in dense humid forests, since the phytosociological approach is not robust enough to produce such an analysis. Two groups characterised by specific botani¬cal families were identified: “dense humid semi-deciduous forests with Malvaceae and Ulmaceae”, and “dense humid forests with evergreen leguminous species”. How¬ever, some species with high dispersal po-tential, which are abundant in secondary forests, especially Triplochiton and Termi¬nalia, do not fit into this classification. The fact that the areas of distribution of cer¬tain species are discontinuous may be ac¬counted for by seed dispersal, but also by the palaeohistory of the flora and climate. Similarly, the ecological area concept can¬not be applied to rare or locally endemic species. This study also discusses sev¬eral indigenous invasive species, such as Scaphopetalum amoemum and Chidlowia sanguinea, whose growth prevents forest regeneration. Finally, it discusses the pres¬ence within humid forests of patches of sa¬vannah, which are always of edaphic and not anthropic origin. Abstract adapted by the editorial team.

“Secondary” forests are very different to “primary”, “noble” forests with their tall trees. Their exuberant, inextricable vegetation, with more lianas and small shrubs than trees, grows on formerly forested lands cleared for agriculture. In inhabited regions, they generally sur¬round villages and grow along roadsides, pushing the primary forest back to rocky hillsides and swamps. In Equatorial Af¬rica, “secondary” forests account today for 50 to 75% of all forested areas. These forests form in three stages: (i) seedlings appear of fast-growing sun-loving species (Musanga sp., Vernonia sp., Anthocleista sp.), which are not the same as primary forest species and which disperse their seeds over long distances; (ii) formation of an understorey, made up of the same shrub species as in “primary” forests but mixed in this case with a second group of banal sun-loving species characteristic of “secondary” forests, which quickly grow as high as the first group and sometimes higher; (iii) gradual reconstitution of “pri¬mary” forest with abundant Sapotaceae, Guttiferae and hard-wooded legu-minous species that are capable of regenerating in the undergrowth and through which some very tall trees eventually grow through the canopy. Okoumé (Aucoumea klaineana), a valuable species typical of “secondary” forests, is common in the so-called “primary” forests of Gabon, which in fact are on formerly cleared forest land. Today, the high potential of these “sec¬ondary” forests must not be allowed to “go up in smoke”. Quite the reverse: we must learn to guide their development to hasten the establishment of commercially valuable species. Abstract adapted by the editorial team.

A dispute has erupted in Madagascar between naturalists and the Water and Forests Service, on the subject of reforestation with eucalyptus. The matter specifically concerns the 3,000 hectares of plantations established since 1908 at Périnet, in a highly degraded forest invaded by bamboos, to supply fuelwood for railway engines. Yet this aversion for eucalyptus trees seems unwarranted given the convincing results of the trial plantations at Anamalazaotra, but also outside Madagascar, in Brazil, Kenya, Morocco and Ethiopia for example. Madagascar's capital, Tananarive, and its surroundings are now wooded thanks to the eucalyptus plantations (E. robusta, E. maculata) and their vigorous stump shoots that provide the local population with wood for cooking and construction. Eucalyptus plantations could also halt the erosion which is becoming widespread in Madagascar, particularly on the barren lavaka-scarred slopes of the Lake Alaotra basin. Madagascar's tree species are slow-growing, and eucalyptus has no equal for wood production. The use of eucalyptus can only be rejected for the purely sentimental reason that the species does not belong to the indigenous forest. Furthermore, in Madagascar's eastern forests, the climate is humid enough for an under-storey to develop and thus prevent erosion. Finally, it is to be deplored that naturalist societies should wish to challenge the one colonial service that is directly acting against for¬est destruction by listing certain areas for protection, fighting wildfires, protecting useful species and carrying out rehabilitation work. Attempting to discredit the forests service is ultimately harmful to the conservation of Madagascar's forests. Abstract adapted by the editorial team.

Although surface erosion and gullying are insignificant under dense tropical forest cover, severe erosion can occur locally as a result of land slippage in saturated soils. Examples may be observed in Madagascar, in the forests of Anamalazoatra and Marojejy. Another documented case of widespread erosion under forest cover may be found in the Peruvian Amazon, on a steeply sloping mountainside near the village of Merced. These are exceptions, however. During geological periods of tectonic transformation, intense erosion could have occurred under dense forest cover, forming a jagged relief or what are referred to as “badlands”. But in all these cases, erosion under forest cover could only have occurred when the level of riverbeds rose in relation to the level of the sea, as during the Quaternary glaciations. In places where the forest cover has disappeared, the soil is sometimes spectacularly eroded. The same is true of previously forested areas that have recently been severely thinned. Extreme cases may be found in Madagascar, Congo, Gabon, Brazil and the temperate regions of the United States, particularly in the Tennessee copper basin. These examples clearly confirm the anti-erosive value of forests. Once erosion begins, it can only be halted at great cost and over limited areas. Forests are therefore a means to prevent erosion naturally, cheaply and over large areas. Abstract adapted by the editorial team.

During the Bukavu Conference on flora and fauna conservation (26-31 October 1953), a French delegation submitted a recommendation, which was unanimously adopted, calling for an overall policy for nature protection in Africa. The 1933 London Convention, which only addressed the “conservation of fauna and flora in their natural state”, no longer seems adequate: the conservation of a few animal or plant species and the creation of national parks and nature reserves only address particular areas of nature conservation, which need to be extended to protect the whole environment in which African people live. This includes spontaneous vegetation, which protects water and soils and forms not only forests but also indeterminate “bush”. A specific convention for Africa is justified because nature in Africa is different and more seriously endangered than elsewhere. It is in danger because of the extreme climate, but also from bush fires and slash-and-burn agriculture that cannot sustain the undernourished population. Savannah encroachment, soil erosion and impoverishment and desertification are gaining ground. A common policy for all African territories has become essential to ensure their protection, and also to fight epidemics. Africa's nature forms a whole that has no boundaries, but natural regions that interact climatically. Over and above a Charter for nature protection in Africa, the issue is that of protecting Africa's populations, but without subjecting them to scientific planning that disregards their customary practices. Abstract adapted by the editorial team.