Tree species do not respond uniformly to the observed climate change, which may affect the biodiversity and stability of mountain ecosystems. Using tree-ring growth of fir ( Abies alba ), beech ( Fagus sylvatica ), and larch ( Larix decidua ) from the Sudetes and the Carpathians, we combined principal-component analysis with linear and nonlinear models, supported by explainable artificial intelligence, to quantify the climate–growth relationship. In the Sudetes: fir benefits from warmer winters, yet it is constrained by water deficits not only in summer but also in spring. Hot and dry summers have a negative effect on the beech growth. Larch benefits mainly from warmer May but suffers under low summer precipitation. In the Carpathians: fir responds positively to warm winters, but spring and summer water shortages inhibit its growth; beech growth is limited by cold winters and, to some extend, hot and dry summers; larch benefits from higher temperatures in May and, unexpectedly, from lower April precipitation. The most important climatic predictors of growth were identified: for fir, it is the temperature of February; for beech, it is the temperature of July in the year prior to growth; and for larch, it is the temperature of May. The nonlinear nature of the relationship between tree-ring growth and the main climatic predictors, as well as thresholds of predictor values that regulate the growth, were revealed. Currently, it seems that global warming favours fir, moderately benefits larch, but poses an increasingly serious threat to beech. However, water shortages, mainly in summer but also in spring, are becoming a significant constraint for all three species. It seems that the observed and predicted climate changes pose a greater threat to beech and, in general, to the stability of forests in the Sudetes, where summer heat and water shortages are more pronounced.
Danek et al. (Thu,) studied this question.