7 resultados para Prediction of species potential distribution
em Publishing Network for Geoscientific
Resumo:
Understanding species distribution patterns and the corresponding environmental determinants is a crucial step in the development of effective strategies for the conservation and management of plant communities and ecosystems. Therefore, a central prerequisite is the biogeographical and macroecological analysis of factors and processes that determine contemporary, potential, as well as future geographic distribution of species. This thesis has been conducted in the framework of the BIOMAPS-BIOTA project at the Nees Institute of Biodiversity of Plants, which was funded by the German Federal Ministry of Education and Research (BMBF). The study investigated patterns of plants species richness and phytogeographic regions under contemporary environmental conditions and forecasted future climate change in the area of West Africa covering five countries: Benin, Burkina Faso, Côte d'Ivoire, Ghana and Togo. Firstly, geographic patterns of vascular plant species richness have been depicted at a relatively fine spatial resolution based on the potential distribution of 3,393 species. Species richness is closely related to the steep climatic gradient existing in the region with a high concentration of species in the most humid areas in the south and decreases towards the northern drier areas. The investigation of the effectiveness of the existing network of protected areas shows an overall good coverage of species in the study area. However, the proportion of covered species is considerably lower at national extent for some countries, thus calling for more protected areas in order to cover adequately a maximum number of plants species in these countries. Secondly, based on the potential distribution range of vascular plant species, seven phytogeographic regions have been delineated that broadly reflect the vegetation zones as defined by White (1983). However notable differences to the delineation of White (1983) occur at the margins of some regions. Corresponding to a general southward shifted of all regions. And expansion of the Sahel vegetation zone is observed in the north, while the rainforest zone is decreased in the very south.This is alarming since the rainforest shelters a high number of species and a high proportion of range-restricted or endemic species, despite their relatively small extent compared to the other regions. Finally, the evaluation of the potential impact of climate change on plant species richness in the study area, results in a severe loss of future suitable habitat for up to 50% of species per grid cell, particularly in the rainforest region. Moreover, the analysis of the possible shift of phytogeographic regions shows in general a strong deterioration of the West African rainforest. In contrast the drier areas are expanding continuously, although a slight gain in species number can be observed in some particular regions. The overall lesson to retain from the results of this study is that the West African rainforest should be fixed as a high priority area for the conservation of biodiversity of plants, since it is subject to severe contemporary and projected future threats.
Resumo:
Two lithological-stratigraphic intervals have been distinguished in the Morocco basin by a study of lithologic composition of bottom sediments as well as of planktic and bottom foraminifera present in them. Conditions, under which they developed, are discussed.
Resumo:
Samples of zooplankton were collected in the Barents Sea during cruise 11 of R/V Akademik Sergey Vavilov in September-October 1997. Three different sampling methods were used: 30 l bottle, Judey net, and BR net. More than 40 species of zooplankton were revealed. The greatest species diversity occurred in zones of junction of waters of different origin. Within the 100 m upper water layer zooplankton biomass was rather high: aver. 32 g/m**2. The highest biomass was observed in the northeastern part of the region under study and over the shelf of the Russkaya Gavan' Bay. The lowest biomass occurred in the southern part and in the region of the Gusinaya Banka. The average autumn value of zooplankton biomass in the 100 m upper layer (321 mg/m**3) slightly exceeded the multiannual average for the summer period (200 mg/m**3)