Solovieva, Nadezhda; (2000) A palaeoecological study of Holocene environmental change in a small upland lake from the Kola Peninsula, Russia. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

A multiproxy study of Holocene environmental and climate change using sediments of an upland lake in the Kola Peninsula is presented. The potential of diatoms as indirect qualitative indicators of climate change in freshwater lakes is assessed. Since climate can indirectly affect water chemistry parameters which in turn influence diatom distribution, the training set of 25 lakes was generated and diatom-water chemistry relationship was examined using multivariate statistics. pH which may be responsive to climate change was also identified as the most influential variable and a diatom-pH model was developed. Predictive abilities of the KOLA pH model were then compared to the SWAP and AL:PE models and the AL:PE model was found to be the most appropriate for reconstructing past pH of Chuna Lake A sediment core from the lake Chuna was analysed for diatoms, pollen, sediment chemistry, and magnetic properties. Changes in the past lake pH indicate slow acidification but no correlation with climate change. The environmental history of Chuna Lake was divided into two major periods. The first period (9,000 - 4,200 cal BP) is characterised by slow natural acidification and major changes in diatom flora, the shift in the treeline, changes in erosion, sediment organic content and DOC. During this time the changes in diatom composition, species richness and diatom-inferred DOC are largely synchronous with the regional pollen changes, the shift of the treeline and fluctuations of catchment erosion. During the second period (the last 4,200 years) diatom-based proxies show no clear response to pollen and erosion changes. Apparently, autochthonous ecological processes became more important than external climate influence during the late Holocene. Overall, the results suggest that Holocene climate variability can be studied using diatom sediment record. In Chuna Lake the best diatom-based climate proxies are DOC and species richness.

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