Zróżnicowanie struktury igieł polskich populacji sosny zwyczajnej na powierzchni doświadczalnej w LZD w Rogowie

The anatomical and morphological diversity of Scots pine (Pinus sylvestris L.) needles was investigated in nine Polish populations grown on the experimental plots at the Forest Experimental Station of the Warsaw University of Life Sciences – SGGW (Rogów, Central Poland). The experiment started in 1966 and the needle samples were collected from the trees cut down during the thinning treatment in 2016. The following needle traits were measured: (1) length, (2) width, (3) thickness, (4) cross−sectional area of the transfusion tissue, (5) epidermis thickness, (6) width to thickness of the needle cross section ratio, (7) distance between the vascular bundles, (8) number of resin ducts, and (9) length of the needle scales. The results showed that trees from the provenances differ with respect to the studied needle features, however, the differences, for individual traits, are relatively small and in most cases are statistically insignificant as measured by the Kruskal−Wallis test. Statistically significant differences (p<0.05) were found only in case of such features as the number of resin ducts and the length of needle scales. The results may suggest that the environmental conditions of the Polish lowland are not sufficiently diversified to induce clear differences between the individual morphological and anatomical traits of pine needles. However, despite the relatively small differences between the studied populations regarding individual traits, the use of the UPGMA (Unweighted Pair Group Method with Arithmetic mean) dendrogram, taking into consideration the combined effect of all the examined traits of needles, allowed to separate geographically the tested Polish provenances into three groups: I – mid−western (Rogów, Bolewice, Spała, Karsko, Gubin, Tabórz), II – north−eastern (Rospuda, Starzyna) and III – south−eastern (Janów Lubelski). It is suggested that this may be related both to the ability of Scots pine to adapt to local conditions as well as the possibility that the geographical groups of tested populations originated from three different main glacial refugia.