A comparative study of peat proxies from two eastern central Swedish bogs and their relation to meteorological data

Abstract

Analyses of peat humification, testate amoebae, carbon and nitrogen content have been carried out on a peat sequence from Ältabergsmossen. At Gullbergbymossen testate amoebae and peat humification were analysed. Both bogs are located in eastern central Sweden. The longest sequence, Ältabergsmossen, covers the last 150 yr and the data from Gullbergbymossen covers the last 60 yr, both with a time resolution of ca. 2-4 yr cm-1. The different proxies were compared to each other and were also compared to instrumental meteorological data. Correlation between peat humification and C/N ratios is high whereas the correlation is low between these physical/ chemical parameters and reconstructed water tables inferred from the testate amoebae assemblages. High peat humification values and C/N ratios greater than 50 indicate aerobic decay and are thought to reflect the thickness of the acrotelm. High humification values and low C/N ratios are recorded in peat deposited between 1965 and 1980, whereas the dry period starts in the early 1970s according to instrumental meteorological data and inferred water-table depth. The difference in the timing of the onset of a dry-shift between the physical/chemical proxies and meteorological data and testate amoebae derived water table changes is interpreted as renewed decay of already deposited peat. The term secondary decomposition is used for this process. The secondary decomposition process has implications for interpreting physical/ chemical and biological parameters in peat as they may be out of phase during the beginning of a dry-shift. Copyright © 2005 John Wiley & Sons, Ltd.