The influence of former land-use on vegetation and biodiversity in the boreo-nemoral zone of Sweden

Abstract

Pollen analyses were carried out at two sites with contrasting land-use histories (in-field and out-land) within a single estate. The aim was to distinguish the relative importance of natural processes and cultural influence on the development of vegetation and biodiversity. The estate lies in the boreo-nemoral zone of southern Sweden, and attention is focused on the distribution of coniferous and deciduous trees. The in-fields, which lie close to the estate buildings, are currently dominated by deciduous trees, and have a documented history as fields and hay meadows. The more distant out-lands were primarily used as grazing land in the past, and support coniferous forest at present. The study covers the last 4000 yr. 2000-1000 BC: the out-lands site supported natural, dense forests consisting of Quercus, Betula, Tilia, Alnus and Corylus. 1000 BC-AD 1100: several events are best interpreted as an increased cultural activity in the area. Agriculture was based on animal husbandry and the recorded cereals probably originate from a kind of shifting cultivation. AD 1000-1800: agriculture intensified on the in-fields with cereal cultivation of increased importance, while the out-fields were used for slash-and-burn agriculture and forest grazing. The forests became more open in structure but the composition remained unchanged. An increase in Calluna was a possible consequence of over-exploitation. AD 1800 onwards: the out-field deciduous forests were rapidly replaced by Picea-Pinus coniferous forests during the 1800's. The in-fields retained deciduous forest with a continuity of Quercus and other species. There is a close, positive relationship between floristic diversity and cultural influence during the last 4000 yr. A comparison is made with a similar investigation on another estate in the region, revealing small differences between the estates, but striking similarities in the effects of land-use types on the development of vegetation. The significance of former in-fields for nature conservation is discussed, particularly as a potential source for increasing the deciduous component in commercial forestry practice.