A POWERFUL INDICATOR FOR QUANTITATIVE RECONSTRUCTION OF OMBROTROPHIC MIRES PALAEOHYDROLOGY:ADVANCES IN THE STUDY OF FOSSIL TESTATE AMOEBAE

According to chemical conditions,peatlands usually have three types:minerotrophic,ombrotrophic and transition.Nutrients of ombrotrophic mires mainly come from precipitation.Because surface water in the mires moves quite slowly,most of deposits remain their formative sets.There are a number of testate amoebae on ombrotrophic mires,which are single-celled organisms in which the cytoplasm is enclosed within an external shell.Studies of their ecology show that assemblages are principally determined by moisture status but are also influenced by nutrient status,especially by pH levels.Testate amoebae provide an additional technique and have ability to quantitatively reconstruct water table depths.The paper introduces the method and steps of building up a large quality modern dataset of surface sediment samples and associated environmental variables on ombrotrophic mires,which is precondition of reconstruction of palaeohydrology,and then reviews existing and recently developed application of testate amoebae analysis to reconstruct palaeohydrology of ombrotrophic mires.In Europe and North America,many researches have found that the records of water table levels on ombrotrophic mires based on testate amoebae analysis well agree with bog surface wetness(BSW)from plant macrofossils and humification analysis,and are also correlated with the ice rafted debris(IRD)record in the North Atlantic Ocean and cosmogenic isotope flux.The results indicate that testate amoebae are sensitive indicators for paleohydrology,and water table reconstructions from testate amoebae can provide a new source of palaeoclimate data for temperate oceanic regions with ombrotrophic mires.In China,little progress has been made now in the utilization of testate amoebae for reconstruction of palaeohydrology.Obviously,there are potentials to use testate amoebae in the peatlands of China as an indicator for environment,and the researches are useful scientific guidance for the ecological management and the exploitation of the peatlands in China.