© 2007 Heron Publishing—Victoria, Canada
Effects of elevated atmospheric CO2 concentration on the nutrient uptake characteristics of Japanese larch (Larix kaempferi)
Takuro Shinano (1, 5), Takuya Yamamoto (2), Keitaro Tawaraya (3), Masaru Tadokoro (2), Takayoshi Koike (4) and Mitsuru Osaki (2)
1. Creative Research Initiative “Sousei,” Hokkaido University, Kita 21, Nishi 10, Kitaku, Sapporo, 001-0021, Japan / 2. Graduate School of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kitaku, Sapporo, 060-8589, Japan / 3. Faculty of Agriculture, Yamagata University, 1-23, Wakabamachi, Tsuruoka, 997-8555, Japan / 4. Hokkaido University Forest, Field Science Center for Northern Biosphere, Sapporo 060-0809, Japan / 5. Corresponding author (takuro@chem.agr.hokudai.ac.jp) / Received January 16, 2006; accepted April 5, 2006; published online October 2, 2006
Summary
We evaluated the response of Japanese larch (Larix kaempferi Sieb. & Zucc.) to elevated atmospheric CO2 concentration ([CO2]) (689 ± 75 ppm in 2002 and 697 ± 90 ppm in 2003) over 2 years in a field experiment with open-top chambers. Root activity
was assessed as nitrogen, phosphorus and potassium uptake rates estimated from successive measurements of absorbed amounts.
Dry matter production of whole plants was unaffected by elevated [CO2] in the first year of treatment, but increased significantly in response to elevated [CO2] in the second year. In contrast, elevated [CO2] increased the root to shoot ratio and fine root dry mass in the first year, but not in the second year. Elevated [CO2] had no effect on tissue N, P and K concentrations. Uptake rates of N, P and K correlated with whole-plant relative growth
rates, but were unaffected by growth [CO2], as was ectomycorrhizal colonization, a factor assumed to be important for nutrient uptake in trees. We conclude that improved
growth of Larix kaempferi in response to elevated [CO2] is accompanied by increased root biomass, but not by increased root activity.
Keywords:
ectomycorrhizal colonization, nutrient uptake rate, root growth, root:shoot ratio.
