Paleoecology, interdisciplinary science aimed on making a comprehensive reconstruction of past environments and investigating mechanisms and correlations which determine ecological changes on a local, regional and global scale. It is possible to recognize the structure and function of past ecosystems by analysing fossil plant and animal remains and determining the physical parameters of deposits of known age using paleobotanical, paleozoological and geochemical methods.
The object of study are accumulations of remains formed through the deposition of residue of defunct organisms in lake and peat bog sediments and other geological deposits. The survival of these remains is decided by e.g., anaerobic conditions prevailing in the sediments and their favourable chemistry.
Elements of past terrestrial and aquatic ecosystems, climatic change and various forms of human activity are reconstructed using bioindicator properties of plants and other groups of organisms some of which (specialist species) can thrive only in a narrow range of environmental conditions and are not tolerant of change in parameters of physical factors (temperature, humidity, water reservoir depth), chemical factors (oxygenation and salinity of water) or food supply (trophic levels of a water reservoir or a plant community). In interpreting the fossil record the assumption is made that factors responsible the past for the distribution of organisms are approximately the same as today and had similar effects; only their configuration was subject to change, causing transformation within ecosystems.
The main method of p. is pollen analysis which makes possible reconstruction of the history of vegetation in different scales of time and space and supplies crucial data for the reconstruction of past climatic change. Other methods of paleobotany include analysis of plant macrofossils, xylological and anthracological analyses, phytolith and diatom analyses. P. also encompasses the study of remains of all animal groups, ranging from protozoa (Rhizopoda, Foraminifera, Radiolaria), through crustaceans (Cladocera and Ostracoda), insects (Coleoptera – beetles and Diptera – flies, including Chironomidae) and molluscs, to vertebrates. Findings from the analysis of these groups of organisms are used to reconstruct change in climate, water level, trophic status of water reservoirs and peatbogs etc. Another source of information on past environments are geochemical analyses of sediments which help us recognize the conditions of sedimentation, erosion processes, changes in trophic status, productivity and salinity of water reservoirs, contamination of the environment by heavy metals, and climatic change. DNA analyses are used increasingly often to secure evidence on the presence of taxa of some organisms which cannot be identified using microscopy methods.
Findings obtained with p. methods are used to trace long-term changes of the environment in the past. They also serve as input for assessing potential changes of the environment in future, e.g., in climate, sea levels and biotic elements of the environment, under impact from both natural and anthropogenic factors.
ML, JŚM, AP, MZ
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