Abstract ID: 3.13814 | Accepted as Poster | Poster | TBA | TBA

In the present study, the rate of mid-year spruce growth was analysed at a dozen measurement sites representing diverse topo-climatic conditions in the Western Sudetes (medium-sized mountain barrier straddling the border between Poland and the Czech Republic). For three consecutive growing seasons (2022-2024), air temperature and humidity, atmospheric precipitation, soil moisture, changes in trunk circumference were measured using electronic band dendrometers and cambium dynamics by collecting micro-core at two-week intervals (methodology according to Trephor). The spatial variability of topo-climatic conditions in the Western Sudetes is greatest in the lower subalpine forest (700-900 m a.s.l.). The averaged date of the last spring frost in the Western Sudetes varies from the end of April at sites located on slopes to the end of June in the region of flat-bottomed basins. Closed depressions create optimum conditions for the formation of nocturnal radiation inversions (cold air stagnation), which translates into high frequency and depth of frosts. These can occur even in the optimum summer and cause serious forest damage in the form of freezing of fresh annual growth of trees. Following this, dendrometric measurements and micro-core analysis showed significant differences in the mid-year growth rate of trees between sites. The extreme differences in annual ring width were more than fivefold. The topo-climatic variation was compounded by the specific weather conditions observed in the following three growing seasons. All growing seasons were characterised by a positive temperature anomaly (from +0.8 to +2.3 C) and a negative precipitation anomaly (from -7 to -23% of normal). During periods of spring and summer drought, spruce trees showed premature growth stop or reduced growth rates in all elevation floors. However, the lowest radial growth during dry and warm growing periods was observed in the foothills floor and the highest in the upper forest zone. In summary, the climate-growth correlations highlighted the inter-seasonal influence of climatic conditions, particularly rainfall deficit and soil moisture, on the short-term responses of trees. Thus, in line with the projected increasing frequency of drought in the growing seasons, the forest ecosystems of the Western Sudetes are expected to show lower growth performance.