Climatic sensitivity and the growth prospects of Silver fir and European larch in the Carpathians in the light of observed climate changes

One consequence of climate change is the rapid extinction of spruce monocultures in the Carpathians. Therefore, the need has arisen to replace spruce with other highly productive species that ensure the stability and biodiversity of mountain forests, such as the Abies alba and Larix decidua. These co-occurring conifers show different successional and phenological characteristics: L. decidua is a light-demanding species that dominates in the early successional stages, while A. alba is a shade-tolerant tree. This study attempts to identify climatic factors that determine the tree-ring width of fir and larch in order to assess the growth prospects of these species in the context of the ongoing climate change. As a measure of the vitality of trees, tree-ring widths of 42 sub-populations of fir and 36 of larch from the area of the Western Carpathians were used. Regional growth patterns for each species were used to estimate the relationship between temperature/precipitation and radial growth. Linear correlation analyses and nonlinear Random Forest models were used. Fir growth was significantly positively influenced by the high temperature of January–March and July and the high precipitation of February and July of the year of tree-ring formation. Larch growth was positively affected by the high temperature of May and the low precipitation of April and September of the year of tracheid formation. Unlike larch, fir growth increased if May and June of the preceding year were warm. The dominant climatic factor influencing fir growth was February temperature, whereas for larch growth, it was the May temperature of the year of tree-ring formation. Most of the recently observed changes in climatic factors that are important for the growth of both species are favorable. Thus, increasing their share in the Carpathian forests seems fully justified, as this will contribute to the stability, productivity, and biodiversity of the region’s forests.