Root Production of Fagus crenata Blume Saplings Grown in Two Soils and Exposed to Elevated CO2 Concentration: an 11-Year Free-Air-CO2 Enrichment (FACE) Experiment in Northern Japan

Agathokleous, Evgenios; Watanabe, Makoto; Eguchi, Norikazu; Nakaji, Tatsuro; Satoh, Fuyuki; Koike, Takayoshi

Root Production of Fagus crenata Blume Saplings Grown in Two Soils and Exposed to Elevated CO2 Concentration: an 11-Year Free-Air-CO2 Enrichment (FACE) Experiment in Northern Japan

2016

We examined the root production of a set of Fagus crenata (Siebold’s beech) saplings grown in an infertile immature volcanic ash soil (VA) and another set in a fertile brown forest soil (BF) with both sets exposed to elevated CO₂. After the saplings had been exposed to ambient (370–390 μmol mol⁻¹) or elevated (500 μmol mol⁻¹) CO₂, during the daytime, for 11 growing seasons, the root systems were excavated. Elevated CO₂ boosted the total root production of saplings grown in VA and abolished the negative effect of VA under ambient CO₂, but there was no significant effect of elevated CO₂ on saplings grown in BF. These results indicate the projected elevated CO₂ concentrations may have a different impact in regions with different soil fertility while in regions with VA, a higher net primary production is expected. In addition, we observed large elevated CO₂-induced fine-root production and extensive foraging strategy of saplings in both soils, a phenomenon that may partly (a) adjust the biogeochemical cycles of ecosystems, (b) form their response to global change, and (c) increase the size and/or biodiversity of soil fauna. We recommend that future researches consider testing a soil with a higher degree of infertility than the one we tested.

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