Volume 38, Issue 6 p. 740-752
SPECIAL FEATURE

Stand dynamics over 15 years including an outlying population of Fagus crenata at the northern margin of its distribution range in Hokkaido, Japan

Shin-Ichiro Aiba

Corresponding Author

Shin-Ichiro Aiba

Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan

Correspondence

Shin-Ichiro Aiba, Faculty of Environmental Earth Science, Hokkaido University, N10W5, Kita-ku, Sapporo 060-0810, Japan.

Email: [email protected]

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Kanji Namikawa

Kanji Namikawa

Biological Laboratory, Sapporo Campus, Hokkaido University of Education, Sapporo, Japan

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Tetsuya Matsui

Tetsuya Matsui

Forestry and Forest Products Research Institute, Ibaraki, Japan

Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan

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Eri Abo

Eri Abo

Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan

Japan Forest Technology Association, Tokyo, Japan

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Seiji Miyazaki

Seiji Miyazaki

Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan

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Yoichi Tsuzuki

Yoichi Tsuzuki

Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan

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Demidkhorloo Bayarsaikhan

Demidkhorloo Bayarsaikhan

Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan

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First published: 26 October 2022
Citations: 2

Abstract

Fagus crenata, a dominant tree species in cool-temperate deciduous broad-leaved forest of Japan, is continuously distributed northward to the Kuromatsunai lowland of Hokkaido, beyond which its distribution is patchy and isolated. We analyzed stand dynamics over 15 years (2006–2021) in a plot (0.75 ha) including one such outlying population of F. crenata. At the stand level over 15 years, stem density decreased, but aboveground biomass increased. The dominance of F. crenata consistently increased in stem density and aboveground biomass. Change in the relationship between stem density and mean stem mass indicated a successional nature of the stand undergoing self-thinning. Increasing F. crenata dominance and the associated compositional shift was due to the higher growth rates and lower mortality of F. crenata compared to other tree species. Judging from tree-ring analysis, the oldest F. crenata tree in the plot established in 1821, but the density of F. crenata remained low till ca. 1895. The stand started to be affected by persistent disturbance since ca. 1895, with the waves of tree establishment and growth release both peaking at ca. 1930–1960. The F. crenata population mirrored the pattern of the stand, with more pronounced increases during these waves. We suggest that the long-lasting episode of tree establishment and growth release over ca. 1930–1960 was caused by human disturbance, most likely selective logging for fuelwood. The results support the “northward expansion” hypothesis, implying that F. crenata potentially can become dominant beyond the current northern limit of continuous distribution and that disturbance facilitates the range expansion.

CONFLICT OF INTEREST

The authors declare no conflicts of interest.