Vegetational response to tephra deposition and land-use change in Iceland: a modern analogue and multiple working hypothesis approach to tephropalynology

摘要

Evidence is provided from the joint application of tephrochronology and palynology in two Icelandic locations - the island of Papey off the east coast and Seljaland in the south. The Papey study relates to vegetation change around the time of volcanic ash deposition from the eruption of Katla in 1755. This produced various hypotheses concerning volcanic impacts and land-use activities, including changes in nutrient inputs, grazing activity, and climate. Similar data have been obtained from Seljaland, where a group of farms was affected by fall-out from the 1947 eruption of Hekla. The patterns of pollen-based vegetational change were similar at both locations, enabling a fuller exploration of floristic and anthropogenic responses to ash deposition. The Seljaland data are influenced by the known removal of livestock in order to guard against the effects of fluorosis. The resultant cessation of grazing was probably responsible for much of the vegetational change apparent in the pollen record, and this represents a credible recent analogue for processes that may have taken place in Papey in 1755.