How long has the ‘hotspot’ been ‘hot’? Past stand-scale structures at Siggaboda nature reserve in southern Sweden

Fossil pollen and plant macrofossils over the last 2000 years are documented from three small forest hollows in Southern Sweden. One of the sites is inside a 5 ha highly prized old growth mixed Fagus sylvatica and Picea abies forest of high biodiversity which has been protected since 1940. The other two hollows are located 400 and 700 m away in an outlying buffer zone established in 1995 which is mainly coniferous plantation forest. The results show that the area has been forested for at least 2000 years, but that forest composition has been under continuous change, most rapid over the last 200 years. The reduction of deciduous tree pollen particularly Quercus, Tilia, Alnus and Corylus, and the immigration of Fagus and Picea can be observed at all three sites. However, the temperate deciduous trees (Quercus or Fagus) have been much more common in the ‘hotspot’ than in the surrounding forests over the last c. 200 years, and significantly more common at least 2000 years before that. Even though the vegetation has been dynamic through time, the lower human intervention in the ‘hotspot’ area compared with the surrounding matrix forests has facilitated the longevity of deciduous trees and the many rare species which are associated with them. The palaeoecological record of key species and information on past use of the wider forest area revealed in this study, indicates how future management will require flexibility to maintain conservation ‘hotspots’.