Community and ecosystem diversity A. Priority research themes: The following themes were considered as important directions for future research due to the limited knowledge in Central Africa and their pertinence for understanding the dynamics of biodiversity and address conservation issues: 1. Address the organization of community diversity with an evolutionary and functional perspective. Biological inventories are necessary but not sufficient to understand the dynamics of natural communities. Adding phylogenetic and species trait information help assess how the functional roles of the species in the ecosystem, the evolutionary relationships among species and the biogeographic history of species affect species assembly. Hence, hypotheses regarding for example competition, habitat filtering or community neutrality can be tested by integrating trait and/or phylogenetic information into the analysis of community structure (e.g. Webb et al. 2002; Hardy & Senterre 2007; Emerson & Gillespie 2008; Cavender-‐Bares et al. 2009, Schaefer et al. 2011). Conducting such analyses requires species phylogenies and databases for species traits and niche characteristics in addition to standardized species inventories with environmental information. Forest tree communities are among the best inventoried communities in Central Africa due to efforts of botanists (e.g. 1 ha plots) and the inventories conducted by forest companies for management and exploitation plans (the interest of such data to address ecological questions is illustrated by e.g. Parmentier et al. 2011, Rejou-‐Méchain et al. 2011). As phylogenies of tree species are under construction using DNA barcodes, community phylogenetic analysis can easily be applied on tree communities (e.g. Hardy & Senterre 2007). Short term research efforts requires compiling/standardizing datasets (logging companies + botanical inventories), creating functional trait databases (expert knowledge from field botanist) and developing further statistical tools for characterizing the phylogenetic and functional structure of communities. Similar studies should also be conducted on animal communities. However, it is first necessary to identify key sites and taxa with adequate data (e.g. invertebrates, fishes, canopy studies, terrestrial vertebrates). 2. Impact of habitat fragmentation and hunting on key animal species (hornbills, gorillas,…) for plant species regeneration. Many African plants depend on medium-‐sized to large animals for their dispersal and regeneration. Hunting and habitat fragmentation could therefore have profound consequences on the vegetation by changing the relative success of plant species according to their regeneration and dispersal syndromes (e.g. Muller-‐Landau 2007, Stoner et al. 2007, Wang et al. 2007, Wright et al. 2007). However, few quantitative assessments of the impact of hunting and fragmentation on future vegetation changes have been performed in Central Africa (e.g. Blake et al. 2009, Vanthomme et al. 2010). The relatively intact fauna in some preserved areas of Central Africa offer the opportunity to bridge this gap. Research projects should be developed to: -‐
compare plant regeneration in hunted versus intact forests harboring similar flora
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understand the relationship between forest size and community structure in anciently or recently fragmented landscapes and non-‐fragmented landscapes
3. Paleo-‐environment reconstruction A good description of paleo-‐environments is essential to infer the impact of past climate changes and/or human activities on ecosystems (e.g. Adams & Faure 1997). It also permits to scale the rate of change of ecosystems and their resilience to disturbance, providing parameters to model their dynamic. For example, palynological data from sediments proved very informative to document the vegetation history during the Holocene. However, most data in Central Africa come from coastal sites (e.g. Maley & Brenac 1998; Bonnefille 2007, Ngomanda et al. 2007). It is therefore important identify new sites suitable for pollen analyses within the Congo basin (cf. CoForChange project: http://www.coforchange.eu). While paleo-‐environment studies have mostly focused on vegetation, biogeographic and phylogeographic analyses of freshwater species (fishes,…) should provide new insights on the history of hydrological basins (e.g. Bermingham & Martin 1998). This largely neglected subject in Central Africa should be investigated because changes in the delimitation of hydrological basins might reveal major climatic changes related to the amount and distribution of precipitations. At the frontier of scientific progresses, the ongoing development of technologies to study DNA offer new perspectives to study past communities using ancient DNA (de Bruyn et al. 2011). Such approaches proved successful in boreal and temperate areas (e.g. Sønstebø et al. 2010). Although warm tropical regions are much less favorable for DNA preservation, pilot studies should be conducted to assess whether paleo-‐botanical and zoological communities could be inferred from DNA in soil sediments using next-‐generation sequencers. 4. Consequences on communities of biological invasions Biological invasions constitute a major threat to the native biodiversity, especially for isolated ecosystems (e.g. islands; e.g. Mooney & Cleland 2001). In Central Africa this occurs in particular in river and lake ecosystems where introduced fish species can cause substantial disturbances (Balirwa et al. 2003) which are not much documented (García-‐Berthou 2007). Research projects must be developed on the impact of aquaculture on invasive fishes and the resulting changes on native fish species, water turbidity and the invertebrate communities. While continental tropical forest ecosystems are relatively resistant towards invasive species, there are exceptions. One of these is a small stinging invasive ant, Wassmania auropunctata, that currently spreads into African forests where it affects both vertebrate (Walsh et al. 2004) and invertebrate communities (Kendra 2006). However, there is still little knowledge on its impact on for example soil communities (e.g. Le Breton et al. 2003). Hence, studies comparing invaded and non-‐invaded sites should be started.
B. Pertinence for conservation: The following scientific questions are particularly relevant for conservation: -‐
What are the most diverse / original communities for different taxonomic groups?
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What are the environmental / historical determinants of biodiversity patterns?
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What is the resistance and resilience of communities with respect to perturbations (climate changes, fragmentation, unsustainable exploitation, invasive species,…)?
C. Short-‐term / long-‐term activities: 1. Identification of existing inventory datasets and resources, including paleo-‐data 2. Identification/prioritization of new sites [select range of habitats and levels of diversities] 3. Conduct pilot studies and experiments [perturbations; past community reconstruction from DNA] 4. Given pilot studies results, construct large integrative projects to test resistance and resilience across the Congo basin on many taxonomic components and with a strong focus on functional ecology (interactions among guilds). 5. Construct and parameterize predictive models (e.g. climate, population dynamics) D. Strategies for future collaborations (finance, outreach, collaborations, evaluation) 1. Solicit interest from participants at the conference via list serve 2. List funding agencies/programs (with deadlines for applications) E. Facilities available / needed Need for well resolved environmental layers (cf. Michelle Lee). Assess and develop existing networks of paleosites. Develop a high density network of climate monitoring stations (take contact with telephone companies for partnerships using their antennas). Develop a network of hydrological stations in Central Africa analogous to the one developed by IRD in West Africa. Extend standardized monitoring programs on diverse taxonomic groups throughout Central Africa (focus on National parks).
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