Oberhoehendefinition im gleichaltrigen Mischwald.
1996
Sterba H.
The exact definition of Assmann's top height is "the height of the mean basal area stem of the 100 largest (dhb) trees per hectare". In mixed stands there are two possibilities to define this top height. First the 100 largest stems per ha are selected irrespectively of the tree species, and among these 100 stems the height of the mean basal area stem is calculated separately for each species. Second the proportion of tree species by area is calculated, and then for each species the 100 largest trees per ha occupied by this species are selected for top height calculation. The latter method needs an iteration procedure because the proportion of species by area is usually calculated by yield tables which in turn need top height to determine site index. Using the data of 14 plots in mixed Norway spruce (Picea abies L. Karst) and Scots pine (Pinus sylvestris L.) stands show that the calculation of top height from the area occupied by each species results in a population of top height spruce trees, the height diameter ratio of which indicate a poorer sociological position than for pine. Thus site class estimation of spruce would not be a mere expression of site quality but also of competition. Therefore, the definition "largest 100 stems per ha, irrespectively of tree species" should be given preference.
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