Development of phytocoenoses and of above ground production of red oak (Quercus rubra L.) and black walnut (Juglans nigra L.) stands on the PRP series Ivanka pri Nitre

There was studied the influence of moderate crown thinning on development of phytocoenoses and above ground dendromass production in pure and mixed stands of introduced species Quercus rubra L. and Juglans nigra L. Owing to succession process during more than 40 years the other 17 autochthonous tree species, 7 of them (41%) shrubs, have been penetrated in studied stands. The phytocoenoses contain 56 herb species including abundant indicators of the wetted edaphic-hydric order of geobiocoens manifesting that the water regime of soils has not been substantially disturbed by hydro-melioration of surrounding land and the Nitra riverbed regulation. Geobiocoenoses in which the series of permanent research plots has been established belong to the nitrophilous order of geobiocoens, group of forest types Ulmeto-Fraxinetum carpineum and forest type 954 Dry elm-ash forest with hornbeam. The highest reserve of above ground dendromass (686.81 cubic m per ha, 486.501 per ha) and highest mean periodic annual increment (20.58 cubic m per ha year sup(-1), 14.18 t per ha year sup(-1)) were found in the 48-year-old non-tended stand of red oak (80%) and black walnut (20%). The highest growth index of standing volume (414.30%) and the highest percentage of mean periodic annual increment (12.57%) were observed in the tended stand of black walnut (20%) and small-leaved linden (80%), while the highest growth index of dry weight reserve (526.85%) and highest mean periodic annual increment (17.07%) were found in the tended stand of black walnut (80%) and red oak (20%). The highest volume reserve of final-crop trees (299.57 cubic m per ha) was also found in the non-tended mixed stand of black walnut (80%) and red oak (20%), while the highest weight reserve (230.98 t per ha) and the highest mean periodic annual increment (11.27 cubic m per ha year sup(-1), 10.68 t per ha year sup(-1)) were in the tended stand of red oak (80%) and black walnut (20%).