Recent human impact on vegetation in Takkobu, northern Japan, reconstructed from fossil pollen in lake sediments |
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| Authors: | Yuri Kumagai Young Sang Ahn Futoshi Nakamura |
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| Institution: | (1) Imperial College London at the Silwood Park Campus, Ascot, Berkshire, UK;(2) Department of Forest Science, Graduate School of Agriculture, Hokkaido University, Sapporo Hokkaido, 060-8589, Japan |
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| Abstract: | The vegetation of Takkobu, northern Japan, has been significantly altered by land-use development following Japanese settlement
at the end of the 19th century. In order to assess the impact of human activity on vegetation dynamics in Takkobu, changes
in the vegetation composition over the last 300 years were reconstructed from fossil pollen in the sediments of Lake Takkobu.
The pollen assemblage represented broadleaved forests on the surrounding hills and alder forests found on the margin of the
wetland bordering the lake. Prior to Japanese settlement, the hillside forests consisted predominantly of oak. However, with
the onset of land-use development, a significant decline in oak relative to increasing birch was apparent, particularly after
the early 1960s. These results suggest that successive logging since the 1880s had gradually undermined the resilience of
oak. An increase of Artemisia and birch pollen also indicates an expansion of disturbed land. Since the 1960s, a large part of the broadleaved forests
in Takkobu has been converted to larch plantations, although this was not represented in the pollen data because of the underrepresentation
of larch pollen. The results of the pollen analysis have implications for forest restoration in Takkobu. The use of long-term
data allows the determination of the baseline (natural) vegetation to be restored, and also illustrates the factors affecting
present-day vegetation and how it may change in the future. |
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| Keywords: | Forest restoration Human impact Lake Takkobu Pollen analysis Vegetation dynamics |
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