Recent climate hiatus revealed dual control by temperature and drought on the stem growth of Mediterranean Quercus ilex.
A better understanding of stem growth phenology and its climate drivers would improve projections of the impact of climate change on forest productivity. Under a Mediterranean climate, tree growth is primarily limited by soil water availability during summer, but cold temperatures in winter also prevent tree growth in evergreen forests. In the widespread Mediterranean evergreen tree species Quercus ilex, the duration of stem growth has been shown to predict annual stem increment, and to be limited by winter temperatures on the one hand, and by the summer drought onset on the other hand. We tested how these climatic controls of Q. ilex growth varied with recent climate change by correlating a 40-year tree ring record and a 30-year annual diameter inventory against winter temperature, spring precipitation, and simulated growth duration. Our results showed that growth duration was the best predictor of annual tree growth. We predicted that recent climate changes have resulted in earlier growth onset (-10 days) due to winter warming and earlier growth cessation (-26 days) due to earlier drought onset. These climatic trends partly offset one another, as we observed no significant trend of change in tree growth between 1968 and 2008. A moving-window correlation analysis revealed that in the past, Q. ilex growth was only correlated with water availability, but that since the 2000s, growth suddenly became correlated with winter temperature in addition to spring drought. This change in the climate-growth correlations matches the start of the recent atmospheric warming pause also known as the 'climate hiatus'. The duration of growth of Q. ilex is thus shortened because winter warming has stopped compensating for increasing drought in the last decade. Decoupled trends in precipitation and temperature, a neglected aspect of climate change, might reduce forest productivity through phenological constraints and have more consequences than climate warming alone.
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919 Route de Mende, Montpellier, 34293, France.|Agence de l'Environnement et de la Maîtrise de l'Energie, 20, Avenue du Grésillé- BP 90406, Angers, 49004, France.
Morine
M
Lempereur
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919 Route de Mende, Montpellier, 34293, France.
Jean-Marc
JM
Limousin
Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale (IMBE), UMR 7263 CNRS, Aix-Marseille Université - IRD - Avignon Université, Europôle de l'Arbois, BP 8013545, Aix-en-Provence, France.
Frédéric
F
Guibal
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919 Route de Mende, Montpellier, 34293, France.
Jean-Marc
JM
Ourcival
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919 Route de Mende, Montpellier, 34293, France.|Departamento de Biologia, Universidade Federal de Lavras, CP 3037, CEP 37200-000, Lavras, MG, Brazil.
Serge
S
Rambal
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919 Route de Mende, Montpellier, 34293, France.|Irstea, UR REVOVER, 3275 Route Cézanne, CS 40061, Aix-en-Provence, 13182, France.|CEREGE UMR 7330, CNRS - Aix-Marseille Université, Europôle de l'Arbois, BP 8013545, Aix-en-Provence, France.
Julien
J
Ruffault
Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE - IRD, 1919 Route de Mende, Montpellier, 34293, France.
Florent
F
Mouillot
D002980:Climate; D057231:Climate Change; D055864:Droughts; D018547:Plant Stems; D029963:Quercus / Q000254:growth & development*; D012621:Seasons; D013696:Temperature; D014867:Water
D014867:Water

Quercus ilex
; basal area increment; climate change; climate hiatus; climate-growth response; drought; growth duration; growth phenology