Environmental effects on physiological index of black alder (Alnus glutinosa [L.] Gaertn.) dominant trees in central Bosnia

Alnus glutinosa (L.) Gaertn. appears naturally as stands, fragments, patches or river lines mainly around rivers and streams in central Bosnia. Considering spatial frame (mountainous on the headwaters and hilly valley afterward) arises the question of how A. glutinosa responds to exposed climate, hydrology and site conditions. We identified twenty tree temporary sample plots on five sites and conducted measurements of tree dominant trees per plot related to tree structural characteristics (diameter et breast height, height, crown projection) and registered the chlorophyll content index (CCI) in leaves of dominant trees monthly in season 2022. To examine structural, climate, hydrology and site effects on CCI quantity and dynamic we used descriptive statistics, analysis of variance and Kruskal – Wallis test. Obtained results indicated that dominant trees of A. glutinosa reach similar tree dimensions but physiologically responded differently depending on climate factors (mean annual temperature and maximal precipitation) and water (mean annual water flow and water level) fluctuations pointing out site-dependent responses. We notified increase in CCI on the sites exposed to reduced maximal precipitation and shortage of water at the second half of season. Our results confirmed A. glutinosa ability to resist climate challenges and contribute to ecological services on different sites in central Bosnia.