Origin and maintenance of Western Amazon biodiversity: a multidisciplinary approach  Jukka Salo, University of Turku  The Amazon Basin is the worldís most important center of biodiversity, but major elements of this diversity are currently under threat due to deforestation and socioeconomic change. This development has caused an imminent need for a better understanding of the past and present biological processes which maintain and give rise to the high species richness of the area. Unfortunately the current scientific concepts applied in conservation biology of the Amazon Basin are largely handicapped due to poor understanding of the basic geological, climatic and ecological processes of the Amazon. Furthermore, lack of solid data on such components of biodiversity as biogeographic distributions, patterns of endemism, species richness and habitat diversity has lead to the present widely speculative nature of biodiversity studies in the Amazon. This is effectively hindering conservation planning and sustainable use of biodiversity in the Amazonian lowlands.  Recently, fundamentally new data have emerged on geological history, landscape ecology and forest variability in the region. It has been shown that in spite of their uniform appearance, the tropical rain forests of western Amazon consist of a mosaic of dozens or even hundreds of floristically differentiated forest types. The characteristics of the forests depend on the underlying soils, and the distribution of the different soils is under the control of the geological dynamics of the Andean foreland belt. These dynamics have resulted in a dramatic change in the landscape of the western Amazon since the Miocene: from a large Pebas embayment, the landscape has evolved through various stages, such as lacustrine phases, perimarine wide tidal flats and brackish phases to the current riverine ecosystem. This geological history has left its marks both in the edaphic heterogeneity of western Amazonia and in the distribution patterns of the Amazonian biota in ways not yet well understood.  The research program aims at (1) characterisation of Western Amazon geological setting, including tectonism, (2) biogeographic synthesis derived from the historical, edaphic, geological, geomorphical and climate data and (3) development of new land use and conservation models.  The program is a collaborative effort of Departments of Biology, Geography and Geology of the University of Turku and it involves ca. 10 other research institutions in South America and Europe.  Project title:  Origin and maintenance of Western Amazon biodiversity: a multidisciplinary approach  Project leader:  Jukka Salo  Department of Biology  University of Turku,  FIN-20014 Turku, Finland.  tel. +358-2-333 5777, Fax +358-2-333 5730,  e-mail jukka.salo(at) utu.fi