In the locality Zemská (the Low Tatras Mts.) the following aboveground parameters were measured in windthrown and undamaged Norway spruce trees: stem diameter at breast height, stem diameter measured 20cm from ground level, tree height, crown length, and crown width. The stem quotients, crown proportion index, height position of the green crown, and the height of the tree centre of gravity were calculated from these data. Our results agreed with the present understanding that a wide tree crown has a negative effect on spruce stability. Paradoxically, from the view of tree stability, more favourable values of crown proportion index, stem quotients, and height positions of tree centre of gravity were found in windthrown spruce trees. In addition, the forward stepwise method of discriminant analysis identified the variable height position of the tree centre of gravity in the resulting model as the second best predictor (crown width being the first) in distinguishing between windthrown and undamaged spruce trees, although this variable had a higher mean value (less favourable) in undamaged trees.
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