Humic- and fulvic-acid stratigraphy of the holocene sediments from a small lake in Finnish Lapland

Holocene sediments from a small lake (Hirvaslompolo) in eastern Finnish Lapland have been analysed for their content of humic substances. The amount and proportion of humic and fulvic acids were found to be subject to significant changes with time through the Holocene. The humus stratigraphy shows a good correlation with lithe-and biostratigraphical indicators of environmental change at and around the site. The main vegetational changes were the replacement of the early-Holocene birch woods by pine about 7500 yr BP and the retreat southwards of the pine limit since 4000-5000 yr BP. The latter change is associated with climatic cooling and an increase in effective humidity, resulting in the spread of peatlands and a lake-level rise. The present results are preliminary bur nevertheless demonstrate the potential of humus analysis for providing palaeoenvironmental information.