Stopień uszkodzenia drzewostanów jodłowych Gór Świętokrzyskich

The study assesses the damage to silver fir from the canopy layer in the stands of the Świętokrzyskie Mountains (central Poland) using three methods. The suitability of these methods was also analysed by calculating the correlation between increment of the diameter at breast height (DBH) and the level of damage. In total we investigated 240 trees. The first analysed method involves tree defoliation. The mean defoliation of sample accounts for 47.8%, while majority of the trees were found to be within 2nd damage class (fig. 1). Absolute and relative DBH increment does not correlate with tree defoliation strongly (tab.). The next method is based on the assessment of the average tree damage index W that takes into account defoliation, top condition and vitality. In general, analysed trees were found to have reduced height growth and both branching in the top (fig. 2) and central (fig. 3) section of the crown. Inclusion of the secondary crown in the assessment of tree damage resulted in an increase in the vitality of the whole crown (fig. 3). The assessment of damage based on index W showed that largest proportion of trees was within moderate damage and the value of the damage index was lower than in method based exclusively on defoliation. The last method (morphological−incremental) combines the method based on damage index W with DBH increment (index Wz, formula 3). In the period 1971−1985, most of the fir trees reacted negatively to the environment changes (growth reduction), while the proportion of trees with positive responses decreased. In the period 1976−2000, the proportion of trees with negative response decreased, while the proportion of firs with positive and neutral responses increased (fig. 5). The period 2001−2015 faced the dominance of trees showing neutral growth responses, the proportion of trees with positive responses was fairly high, while the proportion of trees with negative responses was the smallest. The highest value of the correlation coefficient (r=–0.661) was found for the correlation between the relative 10−years DBH growth and damage index Wz2(tab.). Of the three discussed damage assessment methods, this method is therefore considered the most accurate.