At the Rio Summit of 1990 two major problems threatening humanity were identified: climate change and loss of biodiversity. The latter has largely remained an academic topic although the former has been given huge amounts of attention and action is being taken to address its effects. Even so, scientists agree that biodiversity is a key requisite for sustaining life on earth.
In the domain of agriculture, IITA was among the first within CGIAR to look into biodiversity for increasing and stabilizing crop yields, particularly through its work on the biocontrol of pests and diseases.
In the last 20 years, IITA has been researching well-defined beneficial taxa, not only for use in insect and weed control but, in particular, to conserve local biodiversity for basic studies. For example, the secondary forest within the IITA campus in Ibadan, Nigeria, has recently been upgraded with the goal of making it a prime research site for biodiversity. Three years ago, IITA became the recipient of 14 ha of long-time fallow land that lies in a disjointed belt of rainforest in Drabo, southern Bénin. This paved the way for the Institute to carry out a project to rehabilitate this patch of rainforest and to document and conserve the threatened biodiversity found within.
Rehabilitating a forest, or a patch of it
The Drabo Rainforest Rehabilitation is an initiative led by IITA in collaboration with the National Herbarium of the University of AbomeyCalavi and other partners. It aims to protect the highly threatened fauna and flora of the historically separated patches of rainforest in southern Bénin, most of which today are sacred forests with difficult access. These forests harbor species of Lower Guinean/Congolese origin that invaded Bénin from Central Africa after the ice Age, while those of Upper Guinean origin sought refuge from the Ice Age in today’s Côte d’Ivoire and Liberia.
In Drabo, inhabitants of adjacent villages used to see the forest merely as a source of fuelwood, medicinal plants, or wild game for food. This highly extractive perception of the forest among the people living near it is what IITA first wants to change by showing the advantages of living with the forest rather than living from it.
Secondly, IITA wants to observe the transformation of agricultural land, from young fallow to secondary forest, looking at changes in the flora and fauna, particularly insects, as well as physico-chemical factors of soil and water resources.
Until now, these activities have been the outcome of private initiatives and not of a structured IITA program. They relate, however, very well with IITA Bénin’s vision of linking biodiversity with bio-risk management under a climate–change scenario. The forest in Drabo houses a field station and is linked with the renowned IITA insect collection—the biggest and best curated in the whole of West and Central Africa—that backs the Institute’s entire plant protection program and serves the whole region.
The project will help to enhance and protect biodiversity within this patch of rainforest for the benefit of the local farming communities. It supports local NGOs active in environmental education, contributes to the research of the Béninois National Herbarium, and provides field sites for research on insects, plants, and monkeys. Yes, monkeys! In the course of 20 years, two free-living groups (about 20–25 individuals) of the critically endangered, endemic red-bellied monkey, Cercopithecus erythrogaster, have come to call this forest— Sanctuaire des Singes de Drabo Gbo—their home.
Being used to humans observing them, these red-bellied monkeys are arguably the easiest to see as the remaining 500 or so documented animals live in small groups in remnants of forests in other parts of Bénin where they are being hunted and are therefore very reclusive. IITA considers studying these monkeys as significant because they are key indicators of the sustainability of forests with an impact on related agroecosystems. Additionally, through this initiative, we partnered with many nature NGOs and conservationists, resulting in the production of a book on nature conservation in Bénin (Neuenschwander et al. 2011) that is now standard reading in universities and high schools across the country.
The Journey so far
One of the more obvious results of a study of four rainforest sites in Nigeria and southern Bénin is that threatened plants and animals have found refuge. The long-term prospects looked better the farther away the forest was from population centers, if land ownership was secure, and a conservation “champion” was at hand as well as a rare animal or plant inhabitant to make the forest attractive for conservation and ecotourism. Protection by local communities was beneficial, but unfortunately not sufficient in the long term.
Additionally, because of this project, the forest continues to grow, with the adjacent communities accepting responsibility, with IITA, for the forest’s protection. The resident red-bellied monkeys are commonly admired when they curiously follow meetings at the communal central square. The forest gives many people, particularly children, a special feeling of living in a pristine environment.
Scientifically, this project culminated in the 20-year floristic study on the rehabilitation of this 14-ha forest reserve (Neuenschwander & Adomou, submitted). Forest regrowth was encouraged by managing the natural growth of the local fallow vegetation and by bringing in seeds and other propagules from forest islands of Bénin in close collaboration with specialists of the National Herbarium.
The succession to shade-tolerant woody forest species of Guineo– Congolian origin at the expense of extra-regional herbs, the coexistence of species with slightly different requirements and the fate of exotic trees in this natural forest were studied. A quantitative assessment of a homogeneous lot indicated 397 trees/ha, 43.7% of them with stems below 20 cm, and a rich undergrowth of 72,600 smaller plants/ha, proof Caption here IITA. of active rejuvenation. Only 4.2% of all plants resulted from the 1041 introduction events of 222 plant species that were new to Drabo.
A total of 635 species were recorded. In June 2016, the total of 581 surviving species included 224 trees. Among all plants, 244 hailed from the Guineo–Congolian zone and 113 from the three savanna zones; 224 were of extraregional origin. Altogether, 72.8% of all woody plants were of forest and tree–savanna origin, whereas 70.4% of all herbs came from regions outside forested West Africa. Only 70% of all species from the forest zone were in decline but the farther away the origin of the plants, the larger the decline in numbers and vigor. In particular, pan-tropical herbs became ever rarer, with 80% of them declining and remaining confined to the few remaining open spaces along paths.
The forest harbors 52 threatened species out of the 73 IUCN-listed species that could possibly survive in Drabo, with threat categories ranging from extinct in the wild, critically endangered, or endangered, to vulnerable on the Red List of Bénin. Some of these species occur in only one or two other locations in Bénin, making Drabo a sanctuary not only for monkeys but also for plants.
The richness in biodiversity of the rehabilitated forests of Drabo now rivals that of the remnant natural rainforests that dot the region, making it a prime site for research in biodiversity and related topics. As the surrounding landscape becomes increasingly impoverished because of high human population, the maintenance of such islands of biodiversity becomes even more critical for the survival of plant and animal species.
By establishing a protective area that will enable rare and endangered species to establish and propagate themselves, we can help compensate for the impact of human intrusion and the resulting loss of species in the highly fragmented forest landscape of Bénin.
Neuenschwander P, Sinsin B, Goergen G. 2011. Protection de la nature en Afrique de l’Ouest : Une Liste Rouge pour le Bénin. Nature Conservation in West Africa: Red List for Benin. IITA, Ibadan, Nigeria, 365 pp.
Neuenschwander P, Bown D, Hèdégbètan GC, Adomou A. 2015. Long-term conservation and rehabilitation of threatened rain forest patches under different human population pressures in West Africa. Nature Conservation 13: 21–46.
Neuenschwander P, Adomou A (submitted) Reconstituting a rainforest patch in southern Bénin for the protection of threatened plants. Nature Conservation.