The Ntumu (the Beti-Fang), live in the equatorial forest in southern Cameroon, in the north of Gabon and of Equatorial Guinea. They practice a semi-nomadic slash-and-burn form of agriculture. Their farming is highly diversified, mainly of food crops (such as cassava, plantain banana, sweet potato, yam and taro) but they also produce cash crops (cacao, groundnuts). When they clear a plot (1 ha on average), the Ntumu systematically spare certain trees, generally about 15 whatever cutting methods or implements they use: chainsaw or axe. Thus, contrary to what is often stated, selective felling is conducted not because the workforce is insufficient or for lack of time. Nor is determined by the hardness of the timber or the exhausting nature of the task. On the contrary, it is a deliberate traditional practice which requires a sophisticated knowledge of the environment and the different types of forest trees. It demands a long learning period.
Why do the Ntumu spare these trees, “orphans of the forest”, as they call them? Investigation of the species preserved reveals that they have a high social, cultural, agronomic and even ecological value in the long term. They are varieties that can provide food or medicinal resources (fruit and seeds), firewood or construction timber or represent prized hunting grounds. Some species, such as the kapok tree also contribute to the habitat’s fertility; their presence improves food production thanks to the humus generated by falling leaves, flowers and fruit as well as the shade they offer for crops. The three species – Ceiba pentandia, Triplochiton scleroxylon and Terminalia superba – which most particularly play this fertilizing role have a high cultural value and hence together represent a third of all protected trees left in the fields.
The orphan trees have, other than their immediate utility in the Ntumu’s subsistence economy, a driving role in forest regeneration when the fields return to fallow. These trees constitute highly attractive sites for seed-dispersing animals (birds, bats, monkeys) which use them to perch or as shelter against predators and sometimes find abundant food in them. In addition, under their crown, the seed density and diversity (over 100 different species1 have been recorded) are clearly higher than for those observed where no such trees remain. Most of these seeds belong to ligneous species (97% as against 60% in open fields)2. The trees isolated in the fields also create a microclimate which favours, or even accelerates, regrowth of forest species. They supply an input of nutrients (leaves, fruit, animal excreta) and increased soil humidity thanks to the shade under the crown. This shade encourages long-life forest tree species. In contrast, in some areas of the open plots, more short-life heliophile pioneer species are found. These species, most often herbaceous, are sometimes invasive. Forest regrowth thus develops more rapidly and intensively under the orphan trees: they act as the nuclei of regeneration which, when they coalesce will contribute to the rapid reconstitution of the forest cover.
Marie-Lise Sabrie | alfa
Scientists on the road to discovering impact of urban road dust
18.01.2018 | University of Alberta
Gran Chaco: Biodiversity at High Risk
17.01.2018 | Humboldt-Universität zu Berlin
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy