Linked Life Data

20504776

Source:http://linkedlifedata.com/resource/pubmed/id/20504776

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
2010-6-23
pubmed:abstractText
The present study examines the impact of the C source (reserves vs current assimilates) on tree C isotope signals and stem growth, using experimental girdling to stop the supply of C from leaves to stem. Two-year-old sessile oaks (Quercus petraea) were girdled at three different phenological periods during the leafy period: during early wood growth (Girdling Period 1), during late wood growth (Girdling Period 2) and just after growth cessation (Girdling Period 3). The measured variables included stem respiration rates, stem radial increment, delta(13)C of respired CO(2) and contents of starch and water-soluble fraction in stems (below the girdle) and leaves. Girdling stopped growth, even early in the growing season, leading to a decrease in stem CO(2) efflux (CO(2R)). Shift in substrate use from recently fixed carbohydrate to reserves (i.e., starch) induced (13)C enrichment of CO(2) respired by stem. However, change in substrate type was insufficient to explain alone all the observed CO(2R) delta(13)C variations, especially at the period corresponding to large growth rate of control trees. The below-girdle mass balance suggested that, during girdling periods, stem C was invested in metabolic pathways other than respiration and stem growth. After Girdling Period 1, the girdle healed and the effects of girdling on stem respiration were reversed. Stem growth restarted and total radial increment was similar to the control one, indicating that growth can be delayed when a stress event occurs early in the growth period. Concerning tree ring, seasonal shift in substrate use from reserves (i.e., starch) to recently fixed carbohydrate is sufficient to explain the observed (13)C depletion of tree ring during the early wood growth. However, the inter-tree intra-ring delta(13)C variability needs to be resolved in order to improve the interpretation of intra-seasonal ring signals in terms of climatic or ecophysiological information. This study highlighted, via carbohydrate availability effects, the importance of the characterization of stem metabolic pathways for a complete understanding of the delta(13)C signals.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0829-318X
pubmed:author
pubmed:issnType
Print
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
818-30
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
Impact of carbohydrate supply on stem growth, wood and respired CO2 delta13C: assessment by experimental girdling.
pubmed:affiliation
Laboratoire Ecologie, Systématique et Evolution, UMR 8079, Université Paris-Sud XI, 91405 Orsay CEDEX, France. maunoury@univ-metz.fr
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't