Fine-root respiration in a loblolly pine (Pinus taeda L.) forest exposed to elevated CO₂ and N fertilization
Forest ecosystems release large amounts of carbon to the atmosphere from fine-root respiration (Rr), but the control of this flux and its temperature sensitivity (Q₁₀) are poorly understood. We attempted to: (1) identify the factors limiting this flux using additions of glucose and an electron trans...
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Published in | Plant, cell and environment Vol. 31; no. 11; pp. 1663 - 1672 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Oxford, UK : Blackwell Publishing Ltd
01.11.2008
Blackwell Publishing Ltd Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | Forest ecosystems release large amounts of carbon to the atmosphere from fine-root respiration (Rr), but the control of this flux and its temperature sensitivity (Q₁₀) 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 Rr by directly measuring its Q₁₀in situ using temperature-controlled cuvettes buried around intact, attached roots. The proximal limits of Rr of loblolly pine (Pinus taeda L.) trees exposed to free-air CO₂ enrichment (FACE) and N fertilization were seasonally variable; enzyme capacity limited Rr in the winter, and a combination of substrate supply and adenylate availability limited Rr in summer months. The limiting factors of Rr were not affected by elevated CO₂ or N fertilization. Elevated CO₂ increased annual stand-level Rr by 34% whereas the combination of elevated CO₂ and N fertilization reduced Rr by 40%. Measurements of in situ Rr 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 Rr is coupled to daily canopy photosynthesis and increases with carbon allocation below ground. |
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Bibliography: | http://dx.doi.org/10.1111/j.1365-3040.2008.01869.x ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0140-7791 1365-3040 |
DOI: | 10.1111/j.1365-3040.2008.01869.x |