Diagnosis and decision-making criteria to attenuate the effect of global change on biodiversity in the Congo Basin forests

Lead Research Organisation: University of Aberdeen
Department Name: Inst of Biological and Environmental Sci


The CoForChange project will gather for 4 years a unique interdisciplinary team of researchers and forest engineers: (i) from 8 public and private institutions and 4 European countries, (ii) associated to 6 national and international institutions, to explain and predict the possible fate of tropical moist forests (TMF) of the Congo Basin. Those TMF, of world importance for their biodiversity and their major ecosystem services, are experiencing past and ongoing effects of climate and anthropogenic changes. How, why and where will tree species survive a drying trend and an increase in resource use in this region is a challenging issue for Europe - both consumer and producer of African timber - , most involved in policy-making on biodiversity conservation, forest management and carbon stocks issues. The core hypothesis of CoForChange is that: 'water and/or light availability, driven by climate and anthropogenic change, are the predominant factors shaping TMFs characteristics. They filter species depending on their drought tolerance and light requirement. To test this hypothesis, and fulfill our objectives, we will organize our work into five thematic and one integrative workpackages aiming at: (1) mapping and characterizing tree communities and environmental factors; (2) mapping soil water availability and its sensitivity to rainfall pattern; (3) Analysing past changes in vegetation, disturbance and environmental changes; (4) Characterising drought tolerance, light requirements and associated functional traits of tree species (5) Evaluating the ongoing evolution of tree communities and (6) integrating results to provide diagnostic and decision-making tools to attenuate the effects of global change. Our project will mobilize specialists of remote-sensing, populations and communities ecology, functional ecology, hydrology/climatology, pedology, paleoecology and anthropology, both from the north and the south. We will use existing data, in particular extensive pools of satellite imagery and a unique database on forest inventories, acquire new paleoecological data on sediment cores and soil profiles, analyse new archaeological sites and implement controlled drought and light experiments on the main tree species of the Congo Basin region. We will link information on spatial and temporal variation of tree communities composition, spatial and temporal variation of environmental factors, and species functional traits in order to provide European administratives, national forest administrations, private companies and NGOs with operational tools: (i) thematic maps identifying the oldest, less resilient, faster-evolving or more biodiverse communities; (ii) maps outlining the possible impacts of various scenarios of climate change and anthropogenic change (socio-economic drivers) on future tree species distributions and thus TMFs characteristics; (iii) databases on important species environmental requirements, and (iv) identification of endangered species or groups of species. Those tools will address decision-makers needs to reason, on a sound basis, conservation strategies and sustainable management of forests - comprising timber logging rules - and to adapt their related territories and forest management policies.


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Description The objectives were to screen African tree species for their responses to drought and light so that predictions could be made for the fate of moist African forests subjected to a drying climate.

Multivariate analysis of tree species characteristics indicated two contrasting species groups: those with high light demand, rapid growth and low wood density (Pioneers) and shade-tolerant species with slower growth and higher wood density (non-Pioneers). Because the allocation of species to Pioneer or Non-Pioneer groups has been based on subjective field observation, shadehouse experiments were used to grow tree seedlings in moderate light in order to provide an objective quantification of species responses to light.

Field experiments in the Republic of Congo compared the survival of tree species seedlings in irrigated and droughted plots and measured species traits that were relevant to drought tolerance. It was found that, in general, Pioneer species were more sensitive to drought. A subset of Pioneers, however, were less sensitive, notably those with a distribution in Africa biased to drier climates. Evolution has evidently found different routes in response to drought. The complexity of species traits and their relationship to light and drought are complex, making predictions for the fate of African forests difficult.

Ancillary research assembled tree species lists for 459 forest samples across tropical Africa. Analyses included 1175 species which were arranged along a compositional gradient that was closely correlated with mean annual rainfall and the length of the annual dry seasons. The position of each species on the gradient provides a preliminary indication of species ability to tolerate drought. Species that were experimentally more drought-sensitive were biased in distribution to higher rainfall climates. The same data were also used to propose a pan-African classification of forests and a means to identify new samples to their appropriate class. Seven forest types were defined based on species composition, three for East Africa, two for Central Africa and two for West Africa.
Exploitation Route As part of the overall Biodiversa project, the results will help timber companies and forest authorities in central Africa develop appropriate management plans for their forest resources. The results of the project should find application in the selection of tree species for plantations by avoiding, for example, the use of drought-sensitive species in drier climates. It also indicates that further research is needed to better understand the different natures of species within the two main ecological groups.
Sectors Environment

URL http://www.coforchange.eu
Description informal collaboration with University of Liege at Gembloux 
Organisation University College London
Country United Kingdom 
Sector Academic/University 
PI Contribution Collation and analysis of 459 forest samples from across tropical Africa. Paper submitted to J Biogeogr.
Description informal collaboration with University of Liege at Gembloux 
Organisation University of Wageningen
Country Netherlands 
Sector Academic/University 
PI Contribution Collation and analysis of 459 forest samples from across tropical Africa. Paper submitted to J Biogeogr.