Testacean amoebae in different types of mire following drainage and subsequent restoration
Abstract:Two different types of mire which had been subject to drainage for about 40 years before restoration of the water table have been studied. The abundance and distribution of testaceans were assessed in both mires before and after restoration. Human activities have changed the moisture conditions and surface chemistry of the mires. The occurrence of testate amoebae was related to the peat stratigraphy, plant remains and peat chemistry, and signs of the effects of these human activities were sought.
Testacean shells were abundant throughout the full depth of peat studied in the ombrotrophic bog, but were numerous only in the surface peat of minerotrophic fen. Deeper layers of the fen had only small numbers of testate amoebae. Decomposition of organic material is generally greater at the fen site and has been accelerated during the drainage phase in the bog site, presumably with effects on the occurrence of testacean shells.
Moisture conditions and peat composition were the main factors determining the occurrence of testaceans. In this study the pH of both mires was low and thus all the species were adapted to acidic conditions. Further, certain species showed correlation with mineral elements of the peat. The species that indicated dry conditions in the bog disappeared or their numbers decreased after the restoration. The effect of the moisture gradient was not as clear as before the restoration, and the testacean species seemed to be more dispersed according to the variation in mineral elements.
Document Type: Original Article
Affiliations: University of Helsinki, Department of Forest Ecology, PO Box 27, FIN-00014 University of Helsinki, Finland
Publication date: April 1, 2002