A review of the stand structure of mature sessile oak stands in northeastern Serbia before planned regeneration

Abstract

The paper shows the stand structure of well preserved monodominant, mature sessile oak stands of seedling origin (Quercetum petraeae Čer. et Jov. 1953., sub-association tilietosum (PSP-1) and sub-association typicum (PSP-2)) in the area of National park ''Đerdap'', before planned regeneration. The researchers are based on data collected in 1992 and 1995 on permanent sample plots (PSP) in the period of massive sessile oak decline that started in this area in 1982. The stands are around 150 years old with only sessile oak in the tree layer. In 1992, on permanent sample plot 1 (PSP-1), the tree canopy was estimated at 0.7-0.8, there were 275 trees per hectare with basal area of 35.98 m2·ha-1, stand volume of 470.55 m3·ha-1 and current volume increment of 5.62 m3·ha-1. The mean stand diameter is 40.8 cm and the mean stand height is 24.2 m. In the stand structure, 90.9% of the trees belong to the dominant crown class (CC-1), 57.5% of the trees have good stem quality (SQ-1), 11.3% the of trees have predominantly free isolation of the crown (IC-1), and 91.6% of the trees are healthy (A0). On permanent sample plot 2 (PSP-2), the tree canopy was estimated at 0.7, there were 192 trees per hectare with basal area of 31.38 m2·ha-1, stand volume of 389.06 m3·ha-1 and current volume increment of 4.16 m3·ha-1. The mean stand diameter is 45.6 cm and the mean stand height is 22.8 m. In the stand structure, 91.1% of the trees belong to the dominant crown class (CC-1), 49.5% of the trees have good stem quality (SQ-1), 20.8% of the trees have predominantly free isolation of the crown (IC-1), and 89.6% of the trees are healthy (A0). In 1995 on PSP-1 the ground cover was 0,5 m high on average and it was consisted of abundantly regenerated silver lime. Other tree species are regenerated at a lower population level and have less coverage in the ground cover. In one part of the area, sessile oak is very densely regenerated. On PSP-2 the ground cover was 1,3 m high on average and it was consisted of very densely regenerated sessile oak seedlings of good quality. Other tree species are regenerated at a lower population level and have less coverage in the ground cover. The data show that the stand structure of mature stands in different sub-associations of a monodominant sessile oak stand, that are the result of similar influences, demands a need of divergent silvicultural measures in further management in order to conserve the diversity of monodominant sessile oak stands.