Fine-root respiration in a loblolly pine (Pinus taeda L.) forest exposed to elevated CO2 and N fertilization.

Journal Article (Journal Article)

Forest ecosystems release large amounts of carbon to the atmosphere from fine-root respiration (R(r)), but the control of this flux and its temperature sensitivity (Q(10)) are poorly understood. We attempted to: (1) identify the factors limiting this flux using additions of glucose and an electron transport uncoupler (carbonyl cyanide m-chlorophenylhydrazone); and (2) improve yearly estimates of R(r) by directly measuring its Q(10)in situ using temperature-controlled cuvettes buried around intact, attached roots. The proximal limits of R(r) of loblolly pine (Pinus taeda L.) trees exposed to free-air CO(2) enrichment (FACE) and N fertilization were seasonally variable; enzyme capacity limited R(r) in the winter, and a combination of substrate supply and adenylate availability limited R(r) in summer months. The limiting factors of R(r) were not affected by elevated CO(2) or N fertilization. Elevated CO(2 )increased annual stand-level R(r) by 34% whereas the combination of elevated CO(2) and N fertilization reduced R(r) by 40%. Measurements of in situ R(r) with high temporal resolution detected diel patterns that were correlated with canopy photosynthesis with a lag of 1 d or less as measured by eddy covariance, indicating a dynamic link between canopy photosynthesis and root respiration. These results suggest that R(r) is coupled to daily canopy photosynthesis and increases with carbon allocation below ground.

Full Text

Duke Authors

Cited Authors

  • Drake, JE; Stoy, PC; Jackson, RB; DeLucia, EH

Published Date

  • November 2008

Published In

Volume / Issue

  • 31 / 11

Start / End Page

  • 1663 - 1672

PubMed ID

  • 18684240

Electronic International Standard Serial Number (EISSN)

  • 1365-3040

International Standard Serial Number (ISSN)

  • 0140-7791

Digital Object Identifier (DOI)

  • 10.1111/j.1365-3040.2008.01869.x

Language

  • eng