Photosynthetic characteristics of Dahurian larch [Larix gmelinii], Scotch pine [Pinus sylvestris] and white birch [Betula platyphylla] seedlings native to eastern Siberia [Russian Federation] raised under elevated CO2
2000
Koike, T. (Hokkaido Univ., Sapporo (Japan). Faculty of Agriculture) | Yazaki, K. | Funada, R. | Kitao, M. | Maruyama, Y. | Takahashi, K. | Maximov, T.C. | Ivanov, B.I.
Growth pattern and biomass production of trees will be affected by increasing atmospheric CO2, which may change the vegetation pattern in eastern Siberian where continuous permafrost is present. In this phytotron experiment, effects of enriched CO2 on the shoot growth and photosynthetic parameters were examined to predict future regeneration capacity of major tree species in the permafrost region. The leader shoot of larch and white birch ceased to grow at 80-90 days after leaf unfolding, by contrast, Scotch pine stopped to shoot elongation at ca. 35 days. Growth cessation of seedlings raised under 70 PaCO2 (high CO2) was one week later as compared to seedlings grown under 36 PaCO2 (ambient CO2). Leaf area of white birch raised under high CO2 was smaller than that at ambient CO2, while there was no difference in needle size of larch and Scotch pine grown under both CO2 levels. Specific leaf area (SLA) deceased in all species raised under elevated CO2. There was no significant difference in the photosynthetic rate of the two conifers grown at high and ambient CO2 levels. The photosynthetic rate in white birch measured at the growth CO2 level showed almost the same value, which was considered as homeostatic adjustment. The apparent quantum yield and carboxylation efficiency of larch and white birch raised under high CO2 decreased, while those of Scotch pine showed no difference. Instantaneous value of water use and nitrogen use efficiency in all seedlings raised in enriched CO2 increased especially for Scotch pine. Based on these results, we infer that, in a future elevated CO2 condition, the larger increase in water use efficiency of Scotch pine could enhance its dominance the forest of eastern Siberia region.
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