Search

European beech Fagus sylvatica and Sessile oak Quercus petraea are reaching the north-eastern limits of their natural ranges in northern Poland. According to the projected changes in potential ranges in this region, climatic conditions for both species until 2080 will remain stable. On the other hand, a decrease in the vitality of mature trees and a reduction in their radial growth are currently observed. To understand these contradictory findings, we monitored the cambial activity in both species during two vegetation seasons. 2015 was characterized by a negative water balance, while 2017 was wet. This provided an opportunity to compare how the xylogenesis proceeds in diffuse-porous beech and ring-porous oak during contrasting in the summer precipitation seasons. The forming annual increments were sampled with Presler borer at variable time intervals depending on the leaf phenological phases. The cores were prepared using a sledge microtome and double-stained with safranin and astra blue. Observations of the phases of wood formation and measurements of the width of the forming increments were analysed on the microslide digital images. Differences in the dates of the phenological phases were analysed using Two-Way ANOVA, while the dynamics of the formation of annual increments were fitted to the Single and Double Gompertz function for beech and oak, respectively. The beginning of vessel formation started earlier in both seasons compared to previous studies. Inter-seasonal differences in the duration of spring phenological phases were insignificant for both species, while inter-species differences were significant due to physiological diversity between diffuse-porous beech and ring-porous oak. In dry 2015, cambial activity ceased sooner in both species than in 2017. Differences between oak and beech were insignificant in both years, but statistically significant disparities existed within each species due to varying in precipitation seasons. Rainfall significantly elongated the duration of cambial activity and caused wider tree-rings. According to our study, despite predicted maintaining their climatic niche, both species, situated at the north-eastern cooler range boundary, are expected to produce wood at a lower rate due to the projected warmer central European climate with increased heatwaves and summer droughts. [ABSTRACT FROM AUTHOR]

• Native and non-native pines react uniformly to drought. • Local site conditions diminished interspecific variation. • No evidence that alien pines are better adapted to climate change than native pines. Two European pine species, Pinus sylvestris and Pinus nigra , are experiencing dieback as a result of the increasing frequency and intensity of extreme climatic events. Recent species distribution models predicted shrinkage of ecological niches in the near future and shifted their habitat range towards the northeast. Consequently, P. sylvestris may contract its range and P. nigra may expand in Central Europe. To test whether native pine species have an advantage over introduced pine species in acclimation to a novel climate in Central Europe, we investigated the climate sensitivity and vitality of P. sylvestris, P. nigra and P. rigida. We sampled mature stands of each pine species at three sites in Central Europe, for which we determined climate–growth relationships: temporal stability of temperature and precipitation correlations with tree-ring width and resilience indices. Based on remote sensing data, we assessed differences in surface reflectance and photosynthetic activity obtained from the normalised difference vegetation index (NDVI). Our analyses revealed that the climate sensitivity and surface reflectance of pines are not due to their nativeness in Central Europe but better explained by local site conditions. The specificity and variability of drought events may determine both the homogeneous and diverse susceptibility of species to a negative water balance. Therefore, the character of future climatic extremes seems to be the key to understanding the acclimation of native and non-native pine species in Central Europe. Because our study do not provide evidence of the superiority of non-native pine species over P. sylvestris , and the potential impacts of introduced species on local habitats seem poorly understood in the face of climate change, we urge particular caution in introducing species with unrecognized invasive potential. [ABSTRACT FROM AUTHOR]