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
Species may appear deceptively resilient to climate change
24.11.2017 | University of California - Davis
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences