Simple asymmetry indicators tested in natural even-aged Scots pine (Pinus sylvestris L.) stands in Bulgaria

Abstract

Based on 101 sample plots laid in Scots pine forest dendrocenoses aged 72 as an average with fulness around and over 0.7 has the structure in thickness, more exactly – the asymmetry of the distribution of tree numbers according to thickness, been investigated. Based on a retrospective analysis theoretically proved new indices have been introduced for finding and investigating this asymmetry, as well as a new indicator of asymmetry. The results obtained show that: a). The indices of asymmetry and the indicator of asymmetry, which proceeds from the indices, are in a close correlation (R2 = 0.93; 0.94) with the coefficients of asymmetry and are suitable for generalised comparative studies. b). The currently used generalised indicator of asymmetry – the zero natural indicator has a weaker correlation with the coefficient of asymmetry as compared with the correlation between the index of asymmetry and the indicator of asymmetry. c). The comparison between the indices of asymmetry for thickness structure and the indices of steepness for height structure has revealed a common trend as to inversely proportional change in these two kinds of indices and their correlation is R = 0.26. The general conclusion is that the indices and indicators of asymmetry are completely suitable and effective for generalised comparative studies such as, for example, the comparison between the structures in thickness and height of forest dendrocenoses.