Antoine Cabon, Patrick Fonti, Georg von Arx, Franco Biondi, J Julio Camarero, Filipe Campelo, Marco Carrer, Katarina Čufar, Henri Cuny, Annie Deslauriers, Marek Fajstavr, Marina Fonti, David Frank, Alessio Giovannelli, Andreas Gruber, Jožica Gričar, Vladimír Gryc, Aylin Güney, Minhui He, Petr Horáček, Jianguo Huang, Malcolm Hughes, Yuan Jiang, Hans-Peter Kahle, Gregory King, Alexander V Kirdyanov, Elena Larysch, Xiaoxia Li, Eryuan Liang, Martín de Luis, Harri Mäkinen, Edurne Martínez Del Castillo, Sergei Mikhailov, Tobias Walter Miller, Kiyomi Morino, Cristina Nabais, Walter Oberhuber, Momchil Panayotov, Richard L Peters, Peter Prislan, Sergio Rossi, Seyedehmasoumeh Saderi, Antonio Saracino, Luigi Saulino, Roberto Silvestro, Thomas Seifert, Anne Sophie Sergent, Dominik Florian Stangler, Marko Stojanović, Vaclav Treml, Hanuš Vavrčík, Joana Vieira, Wenjin Wang, Gerhard Wieser, Bao Yang, Yiping Zhang, Emanuele Ziaco, Cyrille B K Rathgeber
Climate warming lengthens the productive season in extratropical forests. Yet there is inconclusive evidence on whether this in turn elicits enhanced tree growth and forest carbon sequestration. In this study, we used cellular observations of conifer wood formation spanning boreal to semiarid forests to quantify the relative importance of cambial growth rate versus season length in driving annual cell production, the key process underlying woody growth. We found that rate is the primary driver of annual cell production. Furthermore, whereas the growing season lengthens with annual temperature, growth rate exhibited an optimum at ~6°C, beyond which increasingly dry conditions compromise wood production gains. The negative impact of warming on intra-annual growth dynamics can thus largely offset the benefit of longer growing season on future forest carbon storage.