Oaks in Götaland Changing dimensions - increasing volumes Johan Bergstedt, Lars Westerberg, Per Milberg IFM, Biology, Division of Ecology, Linköping Universit y , Sweden. Introduction
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Changing dimensions - increasing volumes
Johan Bergstedt, Lars Westerberg, Per Milberg
IFM, Biology, Division of Ecology, Linköping University, Sweden
Oak have, like other broadleaves, often been considered as an obstacle in forestry during the 20th century. To combat broadleaves foresters have used herbicides, axes and saws. At the same period of time oak-shaded meadows and grazing areas have diminished.
How have these changes affected the standing volume of oak?
The total volume of timber has increased substantially during the 20th century, but even more so the oak. Hence, there is no indication that the oak is being eliminated by modern land use management in Götaland.
During the last 50 years, it is larger oaks (≥35 cm ) in particular that has increased. In contrast, small oaks seems to have decreased somewhat.
What the reasons for these changes are and their relative contribution, is yet to be investigated. The following might be suggested: change in forestry management; cessation of cattle grazing the forests;increased populations of browsers (roedeer, moose); climate change.
Standing volume of oak in million m3 stem volume. All land use classes.
1: The volume
of oak increased
with 421% from the 1920s to 2002
2: The number of stems in the lowest diameter class (0-(9.9 cm) has decreased, while the diameter classes ≥ 35 cm have increased
Number of stems per hectare of oak. Forest land.
Bars indicates 95% confidence interval
≥35 cm in diameter
0-9.9 cm in diameter
1: Estimated standing volumes in Götaland was compiled from published reports issued by the National Forest Inventory of Sweden (NFI).
2: The estimated density of oaks in Götaland
(stems ha-1), in different diameter classes, were calculated from annual data 1953-2002 collected by the NFI. In total, there were 199,859 sample plots, and only trees with a height ≥ 1.3 m were considered.
This work had not been possible without the fieldwork by numerous persons in the NFI over the years. Thanks to Hans Toet, who helped with the extraction from the NFI database.
Financial support was provided by KSLA.