Wood is the main terrestrial biotic reservoir for long-term carbon sequestration(1), and its formation in trees consumes around 15% of anthropogenic carbon dioxide emissions each year(2). However, the seasonal dynamics of woody biomass production cannot be quantified from eddy covariance or satellite observations. As such, our understanding of this key carbon cycle component, and its sensitivity to climate, remains limited. Here, we present high-resolution cellular based measurements of wood formation dynamics in three coniferous forest sites in northeastern France, performed over a period of 3 years. We show that stem woody biomass production lags behind stem-girth increase by over 1 month. We also analyse more general phenological observations of xylem tissue formation in Northern Hemisphere forests and find similar time lags in boreal, temperate, subalpine and Mediterranean forests. These time lags question the extension of the equivalence between stem size increase and woody biomass production to intra-annual time scales(3, 4, 5, 6). They also suggest that these two growth processes exhibit differential sensitivities to local environmental conditions. Indeed, in the well-watered French sites the seasonal dynamics of stem-girth increase matched the photoperiod cycle, whereas those of woody biomass production closely followed the seasonal course of temperature. We suggest that forecasted changes in the annual cycle of climatic factors(7) may shift the phase timing of stem size increase and woody biomass production in the future.

5 N Sukachev Institute of Forest SB RAS Krasnoyarsk 660036 Russia

AgroParisTech UMR 1092 LERFOB Nancy F 54000 France

Biotechnical Faculty University of Ljubljana Jamnikarjeva 101 Ljubljana 1000 Slovenia

Centre for Functional Ecology Department of Life Sciences University of Coimbra Calçada Martim de Freitas Coimbra 3000 456 Portugal

Department of Geography and Regional Planning Environmental Science Institute University of Zaragoza C Pedro Cerbuna 12 Zaragoza 50009 Spain

Department of Geography Queen's University Kingston Canada

Faculty of Forestry and Wood Technology Department of Wood Science Mendel University in Brno Zemědělská 3 Brno 613 00 Czech Republic

Faculty of Science Charles University Prague Prague CZ 12843 Czech Republic

INRA UMR 1092 LERFOB Champenoux F 54280 France

Instituto Pirenaico de Ecología Avda Montañana 1005 Zaragoza 50192 Spain

Key Laboratory of Tibetan Environment Changes and Land Surface Processes and Key Laboratory of Alpine Ecology and Biodiversity Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China

Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems Provincial Key Laboratory of Applied Botany South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China

Natural Resources Institute Finland PO Box 18 Vantaa 01301 Finland

Oeschger Centre for Climate Change Research Bern CH 3012 Switzerland

Siberian Federal University 660041 Krasnoyarsk Russia

Slovenian Forestry Institute Vecna pot 2 Ljubljana 1000 Slovenia

Swiss Federal Research Institute WSL Birmensdorf CH 8903 Switzerland

Université du Québec à Chicoutimi Chicoutimi QC G7H 2B1 Canada

University of Innsbruck Institute of Botany Sternwartestrasse 15 Innsbruck 6020 Austria

Citace poskytuje Crossref.org

Partial asynchrony of coniferous forest carbon sources and sinks at the intra-annual time scale

Dendrometers challenge the 'moon wood concept' by elucidating the absence of lunar cycles in tree stem radius oscillation

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Forward Modeling Reveals Multidecadal Trends in Cambial Kinetics and Phenology at Treeline

Reply to Elmendorf and Ettinger: Photoperiod plays a dominant and irreplaceable role in triggering secondary growth resumption

Photoperiod and temperature as dominant environmental drivers triggering secondary growth resumption in Northern Hemisphere conifers

Axial changes in wood functional traits have limited net effects on stem biomass increment in European beech (Fagus sylvatica)