A palaeoecological study of a hummock-hollow complex from engbertsdijksveen, in the Netherlands

Abstract

From a peat-face in the Engbertsdijksveen (Prov. of Overijssel, The Netherlands), three sections have been sampled, for reconstruction of the regional and local vegetation history of the area around the raised bog and of the bog itself. A detailed discussion is provided of the interval of c. 1000 B.C. to c. 960 AD, comprising the period of the Late Bronze Age to the Early Middle Ages. Different pollen-accumulation rates were correlated with fluctuating human activity in the subsequent periods, being high during the Migration Period (10512 pollen cm −2 yr −1) and lower during the Iron Age (6344 pollen cm −2 yr −1) and Early Middle Ages (6204 pollen cm −2 yr −1). A careful study of the development of the local vegetation is presented, based on the analysis of macrofossils, fungal remains, invertebrates and unknown objects (Types) as well as rhizopods. Humidity indexes were calculated based on the occurring Sphagnum and rhizopod species. The curves showed a good correlation and proved to be important in the interpretation of other aspects like mean peat accumulation rates and the development of the vegetation. Using radiocarbon dates and pollen-concentration on the one hand and bulk-density values, ash contents, fine and coarse fractions and humic acids on the other, mean peat accumulation rates of the various zones could be calculated and compared with other processes taking place during peat formation. The mean peat accumulation rate both in mass and height proved to be high in drier plant communities, dominated by Sphagnum imbricatum (62–73 g cm −2 yr −1 and 1.03–1.59 mm yr −1), which resulted in higher ash contents, while the reverse was true for wetter types, dominated by Sphagnum cuspidatum, with a lower accumulation rate (20–28 g cm −2 yr −1 and 0.36–0.47 mm yr −1). An existing model was used to estimate the production and decomposition rates in the catotelm, and an input of 72.3 g cm −2 yr −1 and a decay rate of 0.00084 yr −1 were observed. A spatial reconstruction of the entire hummock-hollow complex is presented and compared with estimated depths of the watertable and moisture contents.