摘要 : Detailed spatial changes in forest structure in a central Swedish landscape were examined using geographic information system techniques. First, the influence of grazing and burning on forest density and structure in the 19th cent... 展开 Detailed spatial changes in forest structure in a central Swedish landscape were examined using geographic information system techniques. First, the influence of grazing and burning on forest density and structure in the 19th century landscape wereanalysed. Then, the development of the landscape during the 20th century, together with the impact of modern forest management methods on forest structure, were analysed using historical sources. In 1907, over 20% of the 2200-hectare study site was sparsely wooded (12 m3 ha-1) with old trees. These areas have been reforested with single-storied middle-aged and old pine stands (66 m3 ha-1 in 1989) during the 20th century. Fire suppression and changes in land use from subsistence to industrial forestry facilitated Norway spruce (Picea abies) regeneration as undergrowth in open Scots pine (Pinus sylvestris) stands after logging. This natural regeneration has, to a large extent, been cut down and replaced by pine afforestation (the exotic Pinus contorta was planted on about 20% of the clear felled area in the 1980s). During the second half of the 20th century, the standing timber volume has steadily increased, while the mean age of the forest has decreased. Today's young dense forests will result in higher timber values in the coming decades, but the forest has lost a range of ecological niches. 收起