Phytometric assessment of alder seedling establishment in fen and bog: implications for forest expansion mechanisms in mire ecosystems
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Rapid forest expansion as a result of anthropogenic activities has been observed in many mires. However, it is unclear which environmental factors are driving this expansion because there have been no systematic investigations into mire-specific tree seedling establishment. This study investigated factors affecting the establishment of common alder (Alnus japonica) in a mire.
We performed seed sowing and seedling transplantation field experiments to examine the factors influencing germination rate, seedling survival, and seedling growth of A. japonica.
Germination rate and seedling survival period decreased with increasing water level, and seedling dry weight was reduced at pH <6.0. Germination rate was also lower in the fen, whereas seedling dry weight was lower in the bog, which could be reasonably explained by the higher water level in the fen and the lower pH in the bog.
Our results showed that germination and seedling growth in the fen and bog were each inhibited by different mire-specific conditions: high water level and low pH, respectively. Therefore, seedling establishment could be improved by either lowering the water level in fens, to increase germination rate and survival, or raising the pH in bogs, to increase growth.
KeywordsSeedling establishment Seed sowing Seedling transplantation Water level pH
We are grateful to Eri Takada and Syunya Sakai for field and laboratory assistance. We also thank the staff of Kankyo Consultants Corporation and Yuria Momose from the International Crane Foundation for helping with our field study. This study was conducted as part of the Nature Restoration Project in Kushiro Mire in conjunction with the Ministry of the Environment of Japan, and was financially supported by Grants-in-Aid for Scientific Survey (No. 17380100) from the Japan Ministry of Education, Science and Culture.
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