Compensatory mechanisms mitigate the effect of warming and drought on wood formation

Abstract

Because of global warming, high‐latitude ecosystems are expected to experience increases in temperature and drought events. Wood formation will have to adjust to these new climatic constraints to maintain tree mechanical stability and long‐distance water transport. The aim of this study is to understand the dynamic processes involved in wood formation under warming and drought. Xylogenesis, gas exchange, water relations and wood anatomy of black spruce [Picea mariana (Mill.) B.S.P.] saplings were monitored during a greenhouse experiment where temperature was increased during daytime or night‐time (+6 °C) combined with a drought period. The kinetics of tracheid development expressed as rate and duration of the xylogenesis sub‐processes were quantified using generalized additive models. Drought and warming had a strong influence on cell production, but little effect on wood anatomy. The increase in cell production rate under warmer temperatures, and especially during the night‐time warming at the end of the growing season, resulted in wider tree‐rings. However, the strong compensation between rates and durations of cell differentiation processes mitigates warming and drought effects on tree‐ring structure. Our results allowed quantification of how wood formation kinetics is regulated when water and heat stress increase, allowing trees to adapt to future environmental conditions.

Couplings in cell differentiation kinetics mitigate air temperature influence on conifer wood anatomy

“…Concerning the control of the kinetics of cell differentiation processes, the rate and the duration have usually been considered separately. On the one hand, the control of the rate has been associated with a direct influence of temperature on metabolism (Balducci et al, ; Cuny et al, ; Cuny & Rathgeber, ; Mellerowicz et al, ; Proseus, Ortega, & Boyer, ; Proseus, Zhu, & Boyer, ). Cell enlargement implies numerous enzyme reactions (e.g., cutting chemical bonds to loosen the wall, synthesizing, transporting, delivering, and inserting new wall polymers) with high activation energies and thus likely being very sensitive to temperature (Proseus et al, ; Proseus et al, ), whereas the processes involved in wall thickening (e.g., cellulose and lignin biosynthesis, transport, and deposition) are inhibited at temperatures still favourable for photosynthesis (Körner, ; Körner, ; Simard et al, ).…”

Xylogenesis: Coniferous Trees of Temperate Forests Are Listening to the Climate Tale during the Growing Season But Only Remember the Last Words!

“…We found a tight coupling between the duration and the rate of wall deposition (Wodzicki, 1971;Doley, 1979;Stasova, 1993, 1997), and we highlighted its crucial involvement in terms of the response of trees to their environment (Balducci et al, 2016) as well as its consequences in terms of tree-ring structure. Throughout the growing season, increasing durations of wall thickening counterbalanced decreasing wall deposition rates, except at the end of the season, during the formation of the last latewood cells (Fig.…”

“…For that, we quantified the cell development kinetics and the resulting cell dimensions along the tree rings of three coniferous species: silver fir (Abies alba), Norway spruce (Picea abies), and Scots pine (Pinus sylvestris). We then capitalized upon recently published works linking cell differentiation kinetics with tree ring structure (Cuny et al, 2014;Balducci et al, 2016) in order to relate the kinetics (duration and rate) and final result (cell radial diameter and wall cross area) of each differentiation process (cell enlargement and cell wall thickening) to the environmental factors occurring during the corresponding time window. Based on the knowledge reported previously, we hypothesize that the soil water balance directly drives the seasonal changes in cell enlargement kinetics and the resulting cell size, while seasonal changes in wall thickening kinetics and the resulting cell weights are directly constrained by temperature.…”

Water potential control of turgor‐driven tracheid enlargement in Scots pine at its xeric distribution edge

“…Patterns of conduit dimension variations are known to be influenced by environmental cues such as temperature, photoperiod and water availability (Fonti et al ., ; Begum et al ., ; Ziaco et al ., ; Castagneri et al ., ; Pacheco et al ., ), as well as internal factors, such as hormonal signaling or sugar availability (Larson, ; Funada et al ., ; Uggla et al ., ; Winkler & Oberhuber, ). More specifically, temperature and water availability have been shown to affect the kinetics of cell differentiation, the interaction of differentiation rates and durations of enlargement, ultimately leading to final tracheid dimensions and cell wall thickness (Balducci et al ., ; Cuny & Rathgeber, ).…”