The Resistance of European Beech (Fagus sylvatica) From the Eastern Natural Limit of Species to Climate Change

Abstract

In this study, different approaches were used to investigate the vulnerability of beech forests, located at the eastern limit of their natural range, to climate change. To accomplish this, six 2500 m 2 plots were sampled in four European beech forest genetic resources, located in Romania at different altitudinal levels, varying from 230 to 580 m in the Bacău hills and between 650 and 1300 m in the Curvature Carpathian (Braşov region). The analysis of trees phenotypic traits, their radial growth, and the regeneration, did not indicate a vulnerability of the sampled stands to the fluctuations of the environmental factors from the 1950-2014 period. The growth indices of all three populations of Bacău hills are negatively correlated with both June air temperature of current year and September of the previous year. The precipitation amount of September previous year positively influenced the growth indices. The radial growth of plots in Braşov region is slightly linked to the climate. The temperature during the growing season represents a limiting factor for stands that are located outside of the optimal altitudinal species distribution (600-1200 m, in Romania), especially at low altitudes. Our results indicated that a rise of the temperature accompanied by a possible reduction of the precipitations (as is predicted for the coming years) could increase the sensibility of beech forests at lower altitude.

Functional Response Trait Analysis Improves Climate Sensitivity Estimation in Beech Forests at a Trailing Edge

“…Previous and current studies suggest that precipitation-related bioclimatic composites are suitable as an indicator for adaptation and sensitivity at the xeric limit of distribution [19,21,23]. In our study, an extremely high level of the exclusion function was presented by Precipitation seasonality (BIO15, see Table 2), that seems to be an independent and appropriate measure for climatic sensitivity.…”

“…The unfavorable effects of decreasing summer precipitation can also be mitigated by a flexible adaptation as it was concluded from the results of three precipitation variables referring to the hottest months of the year (SDS, BIO16 and BIO19). In our study, Ellenberg's Quotient, the most widely used composite index in relation with climate adaptation and sensitivity (e.g., [15,16,20,22,23]), did not proved to have a powerful sensitivity indication power due to the low ratio of decay function (Table 2). This conclusion is consistent with the findings that EQ ranked 35th of 44 climatic predictors of European forest distribution [11].…”

The Impact of Adverse Weather and Climate on the Width of European Beech (Fagus sylvatica L.) Tree Rings in Southeastern Europe

“…For example, in southwestern Europe, the air temperature in May and the precipitation in the summer and winter months are the main initiators of tree diameter growth. High increment values are observed in rainy years [35]. A study of the responses of beech forests in southeastern Europe [46] found that in June and July, there was no correlation between the growth of trees and air temperature or between the growth of trees and the amount of precipitation.…”

“…Diebacks occur in different biomes and in forests with different climate conditions [34]. The heat wave recorded in 2003 affected central Europe and caused a decrease in the growth and productivity of forests in this part of Europe [35].…”

“…The effect of high temperatures on the width of growth rings is more noticeable at lower altitudes. Reduced rainfall during the growing season is a limiting factor to the growth of beech forests at lower altitudes [35].…”