Agriculture is a main driver in the reduction of rain forest areas in central Africa. Other threats include illegal timber exploitation, game hunting as well as mining. © CC0

Situated around the Equator, the Congo Basin in Central Africa extends across several countries. It is home to the second-largest uninterrupted rain forest area on Earth after the Amazon region. While it is still sparsely populated at 6 to 30 inhabitants per square kilometre, one already sees developments that might have a lasting impact on the countryside. “Population growth has accelerated immensely in southern Cameroon. Most people there are under 25”, reports Stephan Pietsch from the International Institute for Applied Systems Analysis (IIASA) in Laxenburg near Vienna. The biologist was part of an international research team supported by more than 20 partners which developed scenarios for the future of the Congo Basin and its unique biodiversity. In a project funded by the Austrian Science Fund FWF, the IIASA experts adapted their GLOBIOM model for the Congo Basin on the basis of land use and demographic, economic and biological data relating to climate change so as to describe the landscape changes to be expected in the next 50 to 100 years.

Agriculture as main driver of deforestation

One of the central results is the fact that in the coming decades deforestation in the Congo Basin will reach a level comparable to what is seen today in the rain forests of Brazil. According to the experts’ calculations, deforestation will rise by at least 55 and possibly by up to 140 percent in the decade between 2020 and 2030, compared to the period from 2000 to 2010. The areas most affected are the centre of Cameroon and the east of the Democratic Republic of Congo. The surge in population and economic growth bring in their wake an increase in the agricultural use of forestland. One factor is the need to produce food locally, the main crops being manioc and maize as staple foods, as well as peanuts. A second factor is the production of palm oil in the Congo Basin. The cultivation areas for this popular but controversial export product are expected to double by 2030. In terms of greenhouse gas emissions this means the release of 66 to 105 giga tonnes (Gt) of carbon dioxide between 2010 and 2030. Other threats for the forests in the Congo Basin include illegal timber exploitation and game hunting as well as mining.

Predicted loss of forest surface by 2030 (in 1000 ha). Simulation using GLOBIOM. © IIASA

Future scenarios for the preservation of biodiversity

Given that agriculture is a main driver in the reduction of rain forest areas, the Austrian research team also used the BGC-MAN eco-system management model to simulate different land-management scenarios on the basis of varying soil qualities, including regeneration phases for the forest. Traditional shifting cultivation is increasingly being replaced by permanent land use. This shortens the rest periods for the forest which leads to a decline in crop yield. Irrespective of the soil quality – in the Congo Basin fertiliser is hardly ever used for reasons of cost – the forest soil ideally needs at least ten years for regeneration in order to preserve the agricultural production level. In these regeneration phases, the newly growing young trees capture more carbon from the atmosphere than unused forests could. According to calculations from the IIASA team, this reduces the CO2 emissions caused by this type of land use by 16 to 25 percent. In reality, however, the forest fallows are maintained during only three or four years for regeneration.

Recognising changes and understanding processes

“As of yet, biodiversity in the Congo Basin is still high”, emphasises Stephan Pietsch from IIASA, who has been doing research in this area since 2002. Moreover, one could hardly prohibit the population from using their own ecosystems, notes the biologist. “We have done that in Europe with the result that we have no more megafauna”, explains Pietsch. The megafauna of the Congo Basin is well worth preserving. Apart from 10,000 plant species, the forest also offers a home to chimpanzees, gorillas and elephants. “The challenge is to both promote economic development and make sure that development occurs in the right regions”, states Pietsch. This would include keeping large areas under protection. Currently, about 10 percent of the entire Congo Basin is protected. There is also a need for managing access to certain areas in order to prevent illegal hunting or tree felling. Some mechanisms of this kind exist, receiving support from the EU among others. The models developed in this basic research project will enable scientists to recognise changes in the ecosystem early on and to chart the underlying processes. In order to translate these mechanisms into practice, the international research teams also developed process-based role-playing games designed to enable political decision-makers and the general population to develop their scenarios for the preservation of biodiversity and, thus, their own livelihood. “We used role-playing games, for instance, in villages where they can generate social capital and trust”, reports Pietsch. At the regional level they work as instruments of negotiation in order to shape the future development of the region’s forestland.

Personal details Stephan Pietsch holds a research position at the Institute for Applied Systems Analysis IIASA in Laxenburg near Vienna. Pietsch’s expertise lies in the interdisciplinary field of modelling ecosystems, initially focusing on Europe and later extended to tropical regions. The international five-year CoForTips project was carried out until 2017 with the support of the Austrian Science Fund FWF.

Publications and contributions

Bustier B, Ngoy A, Pietsch S, & Mosnier A: Implications of changes in tropical shifting cultivation intensification on land productivity and GHG-related biogeochemistry. In: European Geosciences Union (EGU) General Assembly 2017, Vienna, Austria
Pietsch S, Bednar JE, Mosnier A, & Obersteiner M: Probabilistic Spatial and Temporal Resilience Landscapes for the Congo Basin. In: Systems Analysis 2015 - A Conference in Celebration of Howard Raiffa, 11 -13 November 2015, Laxenburg, Austria
Mosnier A, Tonga P, Mant R, Pirker J, Pietsch S, Bocqueho G, Bodin B, Gillet P, et al.: CoForTips Congo basin forests: tipping points for biodiversity conservation and resilience. Final Report (La modélisation des changements d’utilisation des terres dans les pays d’Afrique Centrale 2000-2030). IIASA Contract No. 13-102, 2017, Laxenburg, Austria
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