Pattern and process in south Swedish forests during the last 3000 years, sensed at stand and regional scales

Authors


Richard Bradshaw (fax 45 38142050; e-mail rhwb@geus.dk).

Summary

1 Two palaeoecological data sets were used to study forest development in the boreo-nemoral zone of southern Sweden during the last 3000 years. Maps of forest types present in 1250 bc, ad 500 and today were compiled from regional pollen data and these were compared with 16 stand-scale pollen analyses.

2 The forest type maps showed a transition from mixed deciduous forest to coniferous forest consisting chiefly of Picea and Pinus. The stand-scale studies recorded the same general development despite site-specific trends. A detrended correspondence analysis displayed the successional trends of the stand-scale sites. All stands moved away from the rich deciduous forest represented by Alnus, Corylus, Quercus and Tilia via Betula and Carpinus to Picea and Pinus forest or, in two stands, to Fagus forest.

3 A rate of change analysis covering the last 3000 years showed that the changes recorded from the last 150 years were the most rapid, but represented the culmination of a transformation that was initiated 850 years earlier. These recent changes completely overshadowed the previous record.

4 The regional maps recorded relatively high proportions of Pinus in the eastern part of the study area throughout the period under investigation. The stand-scale studies indicated that this area had a high fire frequency, while the relatively recent increase in Pinus in south-west Sweden was better explained by anthropogenic influences. The stand-scale data suggested that the regional role of Pinus had been overestimated in southern Sweden

5Corylus, Quercus and Tilia were the major species in the former forests, but began a slow decrease in importance around ad 700. The increasing cereal pollen record was related to the decline of the deciduous forest component, suggesting that anthropogenic activity has been the major driving force in its loss.

6 The combination of regional- and stand-scale studies has provided new insights into forest pattern and process. The local records capture the essential features of the regional record of vegetation history, record forest composition more faithfully than regional sites, and additionally yield insight into processes such as fires that have a regional significance.

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