The effects of nickel in the soil of a deserted asbestos mine on the germination of Betula platyphylla var. japonica and Alnus hirsute
2017
Hirabayashi, K. (Ecosystem Conservation Society (Japan).) | Kimura, N. | Kamoda, S. | Kusumoto, D.
There are deserted asbestos mines in the University of Tokyo Hokkaido Forest. It is hard for plants to survive in these mines because of nickel contained in the soil. With the aim of promoting the restoration of vegetation, we selected Betula platyphylla as a candidate tree species for revegetation at these mines and Alnus hirsuta as a control tree species based on a plant survey carried out in the past. We analyzed exchangeable nickel levels in mine soils and experimentally determined the effects of this amount of exchangeable nickel on B. platyphylla and A. hirsuta in the germination stage. B. platyphylla and A. hirsuta germination rates showed only a small response up to 10 ppm exchangeable nickel stress as the nickel amount in the mine soil. Although the initial growth of B. platyphylla was reduced by these nickel levels, more seedlings of B. platyphylla exposed and extended their roots away from the high-nickel growth medium than did seedlings of A. hirsuta. In 10ppm nickel concentration, more than 60% of A. hirsuta blackened their root tips and seemed to be dying prematurely. When extending its root immediately after germination, B. platyphylla shows sensitivity to nickel levels and avoids highly-concentrated nickel.
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