Growth duration is a better predictor of stem increment than carbon supply in a Mediterranean oak forest: implications for assessing forest productivity under climate change.
Understanding whether tree growth is limited by carbon gain (source limitation) or by the direct effect of environmental factors such as water deficit or temperature (sink limitation) is crucial for improving projections of the effects of climate change on forest productivity. We studied the relationships between tree basal area (BA) variations, eddy covariance carbon fluxes, predawn water potential (Ψpd ) and temperature at different timescales using an 8-yr dataset and a rainfall exclusion experiment in a Quercus ilex Mediterranean coppice. At the daily timescale, during periods of low temperature (< 5°C) and high water deficit (< -1.1 MPa), gross primary productivity and net ecosystem productivity remained positive whereas the stem increment was nil. Thus, stem increment appeared limited by drought and temperature rather than by carbon input. Annual growth was accurately predicted by the duration of BA increment during spring (Δtt0-t1 ). The onset of growth (t0 ) was related to winter temperatures and the summer interruption of growth (t1 ) to a threshold Ψpd value of -1.1 MPa. We suggest that using environmental drivers (i.e. drought and temperature) to predict stem growth phenology can contribute to an improvement in vegetation models and may change the current projections of Mediterranean forest productivity under climate change scenarios.
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 5, France.|Agence de l'Environnement et de la Maîtrise de l'Energie, 20, Avenue du Grésillé - BP 90406, 49004, Angers Cedex 01, France.
Morine
M
Lempereur
Ecologie des Forêts Méditerranéennes, INRA, UR629, F-84914, Avignon, France.
Nicolas K
NK
Martin-StPaul
Laboratoire Ecologie, Systématique et Evolution (ESE), CNRS AgroParisTech-UMR 8079, Bâtiment 362, Université de Paris-Sud, 91405 Orsay Cedex, France.
Claire
C
Damesin
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 5, France.
Richard
R
Joffre
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 5, France.
Jean-Marc
JM
Ourcival
IRD, CEFE, UMR 5175, 1919 Route de Mende, F-34293, Montpellier Cedex 5, France.
Alain
A
Rocheteau
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 5, France.|Departamento de Biologia, Universidade Federal de Lavras, CP 3037, CEP 37200-000, Lavras, MG, Brazil.
Serge
S
Rambal
D002244:Carbon / Q000494:pharmacology*; D057231:Climate Change; D065928:Forests; D019083:Mediterranean Region; D010788:Photosynthesis / Q000187:drug effects; D018547:Plant Stems / Q000254:growth & development*; D011156:Population Density; D029963:Quercus / Q000187:drug effects / Q000254:growth & development*; D011891:Rain; D012621:Seasons; D013997:Time Factors; D014197:Trees / Q000033:anatomy & histology; D014867:Water
D014867:Water; D002244:Carbon
Quercus ilex; carbon partitioning; climate change; drought; extreme event; tree water relation; vegetation models; water deficit