title: Effective use of high CO₂ efflux at the soil surface in a tropical understory plant.
abstract: Many terrestrial plants are C3 plants that evolved in the Mesozoic Era when atmospheric CO2 concentrations ([CO2]) were high. Given current conditions, C3 plants can no longer benefit from high ambient [CO2]. Kaempferia marginata Carey is a unique understory ginger plant in the tropical dry forests of Thailand. The plant has two large flat leaves that spread on the soil surface. We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol(-1)) and the atmosphere at 20 cm above ground level (412 µmol mol(-1)). This finding indicates that the plants capture CO2 efflux from the soil. Almost all of the stomata are located on the abaxial leaf surface. When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol(-1), net photosynthetic rates increased by 45 to 48% under near light-saturated conditions. No significant increase was observed under low light conditions. These data demonstrate that the unique leaf structure enhances carbon gain by trapping soil CO2 efflux at stomatal sites under relatively high light conditions, suggesting that ambient air [CO2] can serve as an important selective agent for terrestrial C3 plants.
authors.affiliation: Center for Ecological Research, Kyoto University, Shiga 520-2113, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ishida
authors.affiliation: Mount Fuji Research Institute, Yamanashi 403-0005, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Institute of Industrial Science, The University of Tokyo, Komaba, Tokyo 153-8505, Japan.
authors.forename: Minaco
authors.initials: M
authors.lastname: Adachi
authors.affiliation: Kansai Research Center, Forestry and Forest Products Research Institute, Kyoto 612-0855, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yoshimura
authors.affiliation: Tomakomai Experimental Forest, Field Center for Northern Biosphere, Hokkaido University, Tomakomai 053-0035, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Osada
authors.affiliation: National Park, Wildlife and Plant Conservation Department, Bangkok 10900, Thailand.
authors.forename: Phanumard
authors.initials: P
authors.lastname: Ladpala
authors.affiliation: Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Sapit
authors.initials: S
authors.lastname: Diloksumpun
authors.affiliation: Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Ladawan
authors.initials: L
authors.lastname: Puangchit
authors.affiliation: 1] Graduate School of Science and Technology, and Department of Mathematical and Systems Engineering, Shizuoka University, Shizuoka 432-8561, Japan [2] Department of Environmental Science and Forest Biology, State University of New York College of Environmental Science and Foestry, Syracuse, NY 13210, USA [3] Marine Biosystems Research Center, Chiba University, Kamogawa, Chiba 299-5502, Japan.
authors.forename: Jin
authors.initials: J
authors.lastname: Yoshimura
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D010944:Plants; D012987:Soil / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D012987:Soil; D002245:Carbon Dioxide