Snow damage to birch stands in Northern Moravia

The condition and snow damage to stands dominated by birch were studied in the area of interest in Northern Moravia. Based on basal area, the share of birch ranged from 68 to 88%. The stands came to existence on fertile sites through natural regeneration and exhibited growth at a level of the best site classes for the Czech Republic. The most severe snow damage to the stands was recorded at the upper stand height of 8-15 m. The extent of damage in the analyzed stands amounted to 67-95% of all trees. The unambiguously predominant type of damage was bending while breakages were recorded only in up to 4% of trees. Slenderness ratios of intact trees differed according to the age (height) of stands. The highest values of about 180 were observed in the youngest, ca 5-years-old and about 5 m high stand. Slenderness ratio values of intact trees in a 17-m high stand ranged about 100. The analyzed stands did not show any differences in the slenderness ratio values between intact and damaged trees. Lower values of the ratio for solitary trees (ca 130) in a 5-years-old stand were accompanied by markedly longer crowns (80% of stem) as compared with trees growing in the stand (60% of stem). Differences in the root system architecture were revealed between intact and damaged trees within a stand of about 9 m in height.