Health condition parameters for deciduous trees in the forest stands of Trostyanetske Forest Enterprise

Abstract

The aim of research was to evaluate the variability and relations with forest health condition its main parameters (defoliation, dieback and epicormic shoots occurrence) in seven tree species: Norway maple (Acer platanoides L.), black alder (Alnus glutinosa L.), silver birch (Betula pendula Roth.), European ash (Fraxinus excelsior L.), English oak (Quercus robur L.), small-leaved lime (Tilia cordata Mill.), and white elm (Ulmus laevis Pall). Research was carried out in 2018 in Trostyanetske Forest Enterprise (Left-bank Forest Steppe; Sumy region). Diameter (DBH), Kraft class, and category of health condition were assessed for each tree. Defoliation, dieback and epicormic shoots occurrence were evaluated as proportion of trees with respective symptoms. Severity of each parameter of tree health condition was estimated using respective scores. No tree species is defoliated over 50%. A birch is characterized by the lowest health condition index (1.6) for living trees, dieback (10%), epicormic shoots occurrence (15.9%) and recently died trees proportion (0.7%), but high proportion of trees died over year ago (10.7%). An oak is characterized by the highest health condition index (2.1), proportion of trees with dieback (45.4%) and epicormic shoots (21.7%). Proportion of trees with dieback is 21.5 to 25% for alder, lime and maple, a bit higher for elm and ash (30.9 and 31.3% respectively). DBH, Kraft class, and health condition index significantly correlate with health condition parameters of analyzed tree species, but the most of correlations are very slight and slight. Correlation between health condition index and defoliation score is significant, positive and high for all tree species (from 0.78 for alder to 0.9 for birch). Correlation between health condition index and dieback score is positive and significant for all tree species, is slight for ash, birch, lime, and alder, and moderate for maple, oak and elm. Correlation between health condition index and epicormic shoots occurrence is significant and positive for all tree species except birch, but is very slight in all cases except elm, where it is slight.