Morphological study of the leaves of two European black poplar (Populus nigra L.) populations in Slovenia

Background and Purpose: Conservation efforts across Europe and a substantial lack of information regarding the present status of black poplar (Populus nigra L.) in Slovenia led us to conduct this research. The objectives were to determine the presence of preserved native black poplar in Slovenia, to evaluate the variation within and between two selected populations, and to evaluate the condition of these populations, which is important for enabling their long-term gene pool conservation. Material and Methods: To determine the black poplar distribution, the national database of growing stock of tree species in sub-compartments was used. Species determination was based on standard determination keys and descriptors. To assess a variation, a morphological comparison of leaves from two black poplar populations from the Sava and Mura rivers was done, as well as a comparison with a Canadian poplar (Populus ́canadensis) clone. Material for analyses was taken from 38 trees, totalling 3811 leaves. Descriptive statistics, non parametric Mann-Whitney U-tests, discriminant analysis (DA) and principal components analysis (PCA) were used