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Fine‐root respiration in a loblolly pine and sweetgum forest growing in elevated CO 2
Author(s) -
George K.,
Norby R. J.,
Hamilton J. G.,
DeLucia E. H.
Publication year - 2003
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 - 10.1046/j.1469-8137.2003.00911.x
Subject(s) - liquidambar styraciflua , respiration , soil respiration , loblolly pine , carbon dioxide , horticulture , botany , carbon fibers , carbon cycle , chemistry , agronomy , zoology , biology , pinus <genus> , ecosystem , ecology , materials science , composite number , composite material
Summary• The loss of carbon below‐ground through respiration of fine roots may be modified by global change. Here we tested the hypothesis that a reduction in N concentration of tree fine‐roots grown in an elevated atmospheric CO 2 concentration would reduce maintenance respiration and that more energy would be used for root growth and N uptake. We partitioned total fine‐root respiration ( R T ) between maintenance ( R M ), growth ( R G ), and N uptake respiration ( R N ) for loblolly pine ( Pinus taeda ) and sweetgum ( Liquidambar styraciflua ) forests exposed to elevated CO 2 . • A substantial increase in fine‐root production contributed to a 151% increase in R G for loblolly pine in elevated CO 2 . Root specific R M for pine was 24% lower under elevated CO 2 but when extrapolated to the entire forest, no treatment effect could be detected. • RG (< 10%) and R N (< 3%) were small components of R M in both forests. Maintenance respiration was the vast majority of R T , and contributed 92% and 86% of these totals at the pine and sweetgum forests, respectively. • The hypothesis was rejected because the majority of fine‐root respiration was used for maintenance and was not reduced by changes in root N concentration in elevated CO 2 . Because of its large contribution to R T and total soil CO 2 efflux, changes in R M caused by warming may greatly alter carbon losses from forests to the atmosphere.