Subproject W04

Prof. Dr. Stefan Porembski, Universitaet Rostock, Institut für Biodiversitaetsforschung,
Allgemeine und Spezielle Botanik, Wismarsche Strasse 8, D-18057 Rostock, Germany

Phytodiversity and dynamics of habitat fragments in the Ivory Coast: spatial and temporal patterns of biodiversity changes, edge effects, and their functional consequences in natural and disturbed ecosystem mosaics

Introduction
The major causes of global biodiversity loss are fragmentation and destruction of ecosystems. The functional consequences of these processes have not been understood yet. There is urgent need to gain detailed insight into functional aspects and factors influencing diversity in natural and disturbed ecosystem mosaics to develop reliable prognoses about future developments.
The Comoé National Park and adjacent areas in the northeastern Ivory Coast were chosen as study areas. They comprise a complex system of quasi-natural and fire-influenced grazed ecosystems in a dynamic forest-savanna mosaic, also including gallery forests of the Comoé river system.
Within this ecosystem complex, annual savanna burning ensures that grazing areas do not become reforested and the remaining forests stay more or less fragmented. Thus, the study area is well-suited for descriptively and experimentally analyzing the relationship between anthropogenic habitat fragmentation and concomitant changes in diversity.
Throughout the entire region, fragmentation of forest ecosystems has been accompanied by a decrease in precipitation during the last decades. The consequences of this decrease on the vegetation are being analyzed by our team in the IMPETUS research project, also funded by the German Federal Ministry of Education and Research (BMBF).

Objectives
The subproject W04 focuses on the spatial and temporal analysis of fragment patterns in the Comoé National Park and of adjacent cultivated land. The analysis of remote sensing data from the past four decades should reveal underlying dynamics of fragment patterns. The present situation is being documented in a GIS-based vegetational map for the purpose of combining biodiversity and geodiversity patterns. This will also serve the other subprojects as a reference and data base.
Recent shifts in diversity are periodically being monitored in the observatories and along sampling transects from closed forests to open savanna. Edge effects along forest-savanna ecotones form a focus of interest, as they increase when fragmentation proceeds. Experimental studies on seed germination and establishment of woody species should unveil crucial processes controlling population dynamics in the field.
Relationships between diversity and dynamics of tropical ecosystems are to be elucidated against the background of current intensification of land use. For this purpose, the effects of human impact on fragment patterns and concomitant changes in diversity are being investigated in consideration of socio-economical aspects by comparing protected and cultivated ecosystems.

Thematic background
Habitat fragmentation in space and time has a profound impact on local and regional diversity patterns in particular, and abiotic and biotic processes are also affected. The major spatial effects of fragmentation are i) a decrease of the area of uninterrupted habitats and ii) an increase in marginal zones. Scientists agree that the latter process has the strongest effect in small fragments. In tropical environments, consequences of fragmentation have been analyzed in natural remnants of rain forests and in artificially established forest islands, cf. "Biological Dynamics of Forest Fragments Project". The consequences were documented for several groups of animals and plants (the latter ones much scarcer!), whereby Africa was strongly neglected.
In the peripheral zones of forest fragments, edge effects become apparent. They influence different abiotic and biotic functional cycles. In general, three types of edge effects can be distinguished:

Cooperation within BIOTA:

The research team:

Prof. Dr. Stefan Porembski, University of Rostock: project leader
Dr. Dethardt Goetze (Postdoc), University of Rostock: coordination, fragment analysis in space and time, biodiversity analysis of fragment patterns in relation to landscape management and structure, vegetation dynamics, plant functional types, GIS vegetation map
Klaus Hennenberg (PhD candidate), University of Rostock: structure of forest-savanna ecotones, analysis and modelling of forest edge effects, regeneration potential of woody species, plant functional types
Annick Koulibaly (PhD candidate), Botanical Laboratories, University of Abidjan-Cocody, Ivory Coast: biodiversity and structure analysis of fragment patterns in settled and cultivated areas, analysis of the utilization regime and the socio-economical conditions, maintenance of biodiversity through sustainable land management, regeneration potential of woody species, plant functional types
Rudolf Pivarci (scientific employee), University of Rostock: support in GIS analyses

External partners of cooperation:

Prof. Dr. Traoré Dossahoua, Laboratoire de Botanique, Université d'Abidjan-Cocody (Ivory Coast)
Centre National Floristique, Université d'Abidjan-Cocody (Ivory Coast)
Centre de Recherche en Ecologie, Université d'Abobo-Adjamé (Ivory Coast)
Conservatoire & Jardin Botanique de la Ville de Genève (Switzerland)
Department of Plant Taxonomy, Wageningen Agricultural University (The Netherlands)
Laboratoire de Botanique, Systématique et de Phytosociologie, Université Libre de Bruxelles (Belgium)
Muséum National d'Histoire Naturelle, Paris (France)
Royal Botanic Gardens, Kew (England)
Université Nationale du Bénin, Faculté des Sciences Agronomiques, Cotonou (Benin)