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Canopy CO 2 enrichment permits tracing the fate of recently assimilated carbon in a mature deciduous forest
Author(s) -
Keel Sonja G.,
Siegwolf Rolf T. W.,
Körner Christian
Publication year - 2006
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2006.01831.x
Subject(s) - canopy , deciduous , tree canopy , environmental science , carbon fibers , botany , isotopes of carbon , carbon cycle , biology , ecology , ecosystem , total organic carbon , materials science , composite number , composite material
Summary• How rapidly newly assimilated carbon (C) is invested into recalcitrant structures of forests, and how closely C pools and fluxes are tied to photosynthesis, is largely unknown. • A crane and a purpose‐built free‐air CO 2 enrichment (FACE) system permitted us to label the canopy of a mature deciduous forest with 13 C‐depleted CO 2 for 4 yr and continuously trace the flow of recent C through the forest without disturbance. Potted C 4 grasses in the canopy (‘isometers’) served as a reference for the C‐isotope input signal. • After four growing seasons, leaves were completely labelled, while newly formed wood (tree rings) still contained 9% old C. Distinct labels were found in fine roots (38%) and sporocarps of mycorrhizal fungi (62%). Soil particles attached to fine roots contained 9% new C, whereas no measurable signal was detected in bulk soil. Soil‐air CO 2 consisted of 35% new C, indicating that considerable amounts of assimilates were rapidly returned back to the atmosphere. • These data illustrate a relatively slow dilution of old mobile C pools in trees, but a pronounced allocation of very recent assimilates to C pools of short residence times.