Xylem anatomy of Robinia pseudoacacia L. and Quercus robur L. is differently affected by climate in a temperate alluvial forest

Abstract

& Key message Xylem hydraulic traits of native Quercus robur are more sensitive to previous-summer drought than those of alien Robinia pseudoacacia. The latter modulates vessel traits and ring porosity to cope with inter-annual climate variability, and is less affected by extreme events. This suggests that R. pseudoacacia might be more competitive under future drier conditions. & Context Forest management strategies require knowledge on how co-occurring native and alien species respond to unprecedented climate conditions, which can severely affect xylem conductivity and tree performance. & Aims We aimed at quantitatively comparing xylem anatomical traits of co-occurring native Quercus robur and alien Robinia pseudoacacia and assessing similarities and differences in their response to climate variability. & Methods We analyzed tree-ring anatomy and built chronologies of several parameters related to vessel number, size, and theoretical conductivity. Mean chronologies for each parameter were correlated to monthly temperature and precipitation data for the period 1954-2005 and within 30-year moving windows. We also assessed responses to extreme conditions in 2003. & Results Quercus robur showed typical ring-porous vessel distribution, while R. pseudoacacia modulated vessel size and number year by year, frequently showing semi-ring porous appearance. Previous rainy summers increased size of large vessels in Q. robur, and number of large vessels in R. pseudoacacia. In winter, R. pseudoacacia was sensitive to water excess. High temperature in March increased vessel size in Q. robur, but reduced it in R. pseudoacacia. The 2003 summer heatwave strongly reduced vessel size and number in the following year in Q. robur, but had much less effect on R. pseudoacacia. & Conclusion Quercus robur xylem traits are more influenced by both inter-annual climate variability and extreme events than those of R. pseudoacacia. Lower performance under dry conditions might reduce competitiveness of Q. robur in the future, slowing down the natural replacement of the invasive pioneer R. pseudoacacia by later-stage Q. robur.

Drought effects on tree growth, water use efficiency, vulnerability and canopy health of Quercus variabilis-Robinia pseudoacacia mixed plantation

“…In contrast, R. pseudoacacia has more conservative water use (Fan, 2010;Nadal-Sala et al, 2017), which partly reflects the differences in xylem structure. R. pseudoacacia produces more vessels, but its diameter appears to be smaller than that of oaks (Nola et al, 2020;Özden Keleşand Savaci, 2021). Greater resistance to water transportation and cavitation under drought conditions may be achieved with vessels of smaller diameters (Sperry et al, 2006), resulting in lower hydraulic conductivity and higher iWUE.…”

Towards Continuous Stem Water Content and Sap Flux Density Monitoring: IoT-Based Solution for Detecting Changes in Stem Water Dynamics

“…However, interspecies variability was more pronounced, especially for those samples collected from the northern sides of the stems. The observed differences in the slope (β 2 ) between the species can be explained by the differences between the species in terms of the area of living tissue, freely available water in the plant tissue, water molecular bounding condition, water potential, wood anatomical structure (small vs. larger vessels), etc., which is the objective of future research [65]. This result suggests that for the same range of frequency change, oak dries at a rate approximately two times greater or more in comparison with diffuse-porous beech under the same experimental condition.…”

How Tree Decline Varies the Anatomical Features in Quercus brantii

“…As a result, the growth of the tree stem diameter decreases. As noted by Nola et al [ 37 ], among angiosperms, the genus Quercus is more sensitive to drought than other species. This suggests that they may be less competitive under drier conditions in the future.…”