Vegetation dynamics and Fire History in Färnebofjärden National Park, Central Sweden

Abstract

Palaeoecological studies can identify past trends in vegetation communities and processes over long time scales. Pollen, plant macrofossils and charcoal analyses are used to reconstruct vegetation over the last 6400 years and provide information about former human impact and disturbance regimes in Färnebofjärden National Park, Central Sweden. Three specific conservation planning topics were addressed: (1) the changing ratio of conifers to broadleaved trees; (2) the origin and history of the river meadows and the biodiverse Populus tremula meadows; (3) the role of fire in the maintenance of biological values. Early diverse mixed broadleaved forest assemblages with pine were followed by significant declines of the more thermophilic forest elements prior to the expansion of spruce in the Iron Age. The rise to dominance of spruce was a ‘natural’ process that has been exaggerated by anthropogenic disturbance to artificially high levels today. The initial river meadow communities were facilitated by fire and frequent flooding events, but subsequent dynamics have more definitely been supported by human activities. Rural abandonment during the last 100 years has led to woody successions. Fire has been a continual disturbance factor with an influence on conservation issues such as Picea abies dominance and the maintenance of diverse, non-forest communities. Present occurrence of fire is unusually low, but natural fire frequencies are increasing in the region.