Subproject W09
Prof. Dr. Elisabeth Kalko, Department of Experimental Ecology (Bio III), Albert-Einstein Allee 11, D - 89069 Ulm
The influence of local and regional factors on the diversity, structure, and function of West African bat communities (Chiroptera)
Introduction
Flying foxes (Megachiroptera) and bats (Microchiroptera) play key roles as seed
dispersal and pollination agents as well as predators of insects and small vertebrates
within African ecosystems. However, the extent of their impact on such fundamental
ecological processes (seed dispersal, pollination, and predation) are still
poorly understood. In particular, the influence of flying foxes on the formation
and regeneration of vegetation patches that are characteristic of and vital
for the highly diverse forest-savanna-mosaics of West Africa is unclear. Moreover,
the fine-grained structure, species richness and dynamics of (micro)chiropteran
assemblages throughout Africa have not yet been studied in sufficient detail.
Preliminary results suggest that flying foxes have major impacts on forest dynamics
as well as on reproductive and establishment potentials of plants. These include
economically important timber and crop trees such as Iroko (Milicia excelsa)
and Karité (Vitellaria paradoxa). Furthermore, first data from our studies
suggest that the diversity of Afrotropical bats has previously been strongly
underestimated. It is much higher than initially thought, probably even approaching
Neotropical levels which have been regarded as the most diverse areas in this
respect. Changes in our view of diversity patterns in West Africa are likely
to radically change our view on the diversity patterns of bats in general. They
also imply that in-depth studies are indispensable to assess the true impact
of this speciose group of mammals concerning regeneration and establishment
of plants as well as partitioning and control of (pest) insects. Additionally,
anthropogenic pressure increasingly affects habitat characteristics in West
Africa. This leads to drastic shifts in the ecological conditions for bats in
the affected areas followed by drastic changes in community structure. The short-
and long-term consequences of such fundamental changes in local and regional
species assemblages on the whole ecosystem are largely unknown.
Objectives:
In our subproject we study the functional importance of bats concerning the shaping and maintenance of biological diversity with special emphasis on vegetation dynamics and community structure of bats across several levels (local, regional and landscape scale). The project is subdivided into three main topics where different aspects of the ecological role of bats are being studied with a broad range of methods. Special emphasis is given to standardized sampling and observation design to allow direct and statistically powerful comparisons. Currently, the main study sites are in Taï and Comoé-National Park, both in Ivory Coast, including a newly established biodiversity observatory. Conceptually and in practice we have initiated tight and interdisciplinary cooperation with local counterparts and with other BIOTA-subprojects (modeling, remote sensing: W01; climate: W02; vegetation dynamics: W04; diversity pattern: W03+W08). Ultimately, the results achieved in our study and through our co-operations will be synthesized to form a comprehensive data base for an in-depth understanding of the impact of Chiroptera on (West) African ecosystems.
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Project part 1: Comparison of species composition
and guild structure of local chiropteran communities at different sites
using standardised sampling methods (ground- and canopy mistnetting, harp
traps, acoustic monitoring). The aim is to understand how vegetation structure
and habitat heterogeneity influences the community structure of bats, especially
their species richness and guild structure. The studies are conducted along
transects within different vegetation zones and precipitation gradients
in the Comoé- and Taï-National Park, Ivory Coast. Because the study sites
are considered to represent fairly pristine habitats, the results will serve
in the main phase as base-line data for the comparison with areas of varying
anthropogenic influence. |
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Project part 2: Predictive modeling of distribution
and large scale diversity patterns using a GIS approach. Already established
data bases on the historical and recent distribution of West African bats
are used to extrapolate the potential and future distribution patterns under
climatic change scenarios, based on biotic and abiotic habitat variables
derived from remote sensing and maps. |
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Project part 3: The role of flying foxes (Megachiroptera)
as keystone species in plant-animal interactions and their influence on
the spatial and seasonal vegetation patterns within the highly dynamic forest-savanna
mosaics of the Guinea Zone. |
The aim of the main phase will be to determine the effect of environmental influences, along an anthropogenically altered gradient, on the spatial and seasonal dynamics and structure of bat communities through the use of predictive models, as well as standardised and comparative experimental field studies. This allows for the development of effective management concepts that maintain the diversity and functionality of this group of animals, as well as the organisms and processes that rely on them. Because of their important ecological roles, Chiroptera are ideal model organisms as indicators for the status of ecosystems in Africa.
The research team:
Dipl. Biol. Jakob Fahr
Dipl. Biol. Njikoha Ebigbo
Prof. Dr. Elisabeth Kalko
Partners in Germany in addition to co-operations within BIOTA
Dr. D. Kock, Mammal Section, Senckenberg Museum Frankfurt/M.;
Prof. Dr. H.-U. Schnitzler, Dep. of Animal Physiology, Univ. of Tübingen
Partners in Ivory Coast:
Dr. J. Tondoh, Univ. Abobo-Adjame, Centre Recherche en Ecologie (CRE), Abidjan;
Prof. L. Ake-Assi & Dr. A. Kadjo Georges, Centre Nationale Floristique (CNF), Univ. Cocody-Abidjan;
H. Gensio Téré, Centre Suisse de Recherches Scientifiques (CSRS), Abidjan
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