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Importance of conservation of the hairy type of Populus nigra in the changing climatic and environmental conditions

Conservation of the genetic resources of some forest tree species, particularly the endangered ones, should have high priority in any large-scale programme of forest ecosystem management. The European black poplar (Populus nigra L.) is a species growing on alluvial soils along large rives in temperate zones in Europe, Asia and Northern Africa. In Croatia, it occurs in riparian floodplain forests along the rivers Mura, Sava, Drava and Danube. Due to permanent human activities in the natural habitats its disribution range has been reduced to smaller, partly isolated stands, although in European terms they form very well preserved riparian forests. The hairy type of the European black poplar (P. nigra ssp. caudina) along the river Neretva in Bosnia and Herzegovina represents the true Mediterranean black poplar. It is characterised by distinct xeromorphism. So far, these poplars have been recorded in two more Balkan areas, in southern Macedonia and in Thessaly in Central Greece, while some populations from Albania and Turkey are also attributed to this taxon. Hairy black poplars from the area along the river Neretva are characterised by distinctly hairy shoots, a short blade and a very short petiole. It grows as a small tree (up to 24 m in height) in relation to the typical subspecies (to 35 m), and it has a less dense crown. Hairiness is retained on one-year- and two-year-old shoots and partially on older shoots as well. Apart from the leaves and shoots, the petioles of inflorescence and fruit are also permanently hairy. In total 5 088 leaves were collected from short fertile shoots of 10 adult trees in each of nine selected natural populations (table 1). Measurments of leaf blade lenght (LBL), leaf blade width (LBW), petiole lenght (PL), angle between the first lower lateral vein and midrib (α ) and distance between the leaf widest part and leaf base (DBW) were taken (fig. 1). Discriminant analyses were performed on assesed morphological data by STATISTICA 6.0 software. Molecular analysis were done on samples from the seven populations from Bosnia and Herzegovina (table 1). Three nuclear genes (win3, PPAL, POPX) and two chloroplast markers were used for the analysis. Results showed distinct differences between typical and hairy types in studied morphological traits. Morphological differences are in accordance with climate differences in respective sites. Putative hybrids from mixed populations are somewhat intermediate between pure types. From molecular analysis, there is nothing special about the „ hairy type“ samples from Bosnia and Herzegovina. They share the same genetic make-up with typical P. nigra, so it could be an „ xeromorphic ecotype“ rather than a subspecies.

hairy type of European black poplar; gene conservation; morphological traits

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