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ŠUMARSKI LIST 5-6/2015 str. 32     <-- 32 -->        PDF

Lefevre et al. (1998) lists three key factors for disappearance of natural populations of black poplar from reduced floodplain ecosystems. The first factor is the control of river systems which leads into the question possibility of riparian species natural regeneration and encourages the replacement of existing populations with hardwood populations; all this brings into the question the survival of the remaining gene pool of the species. Another important endangering factor is over-exploitation of autochthonous poplar in the last century and the mass introduction of superior hybrid Euro-American poplars and American black poplar clones (Romanić 2000), in order to meet the needs of the human population for fast-growing species. As the last given factor is introgression of cultivated poplars as a potential threat to natural populations of poplars. Besides hybrid poplars, which are threat for gene pool and sustainability of native poplar population, different poplar varieties present all over the Europe and wider could threaten the survival of black poplar natural population (Šijačić-Nikolić et al. 2012).
Assessment of black poplar variability along many rivers across Europe, using morphological and genetic markers, have been performed by a number of researchers (Samardžić 1996; Cottrell et al. 1997; Krstinić et al. 1997; Arens et al. 1998, Romanić 2000; Kajba et al. 2002; Alba et al. 2002; Van Dam et al. 2002; Gebhardt et al. 2002; Vanden Broeck et al. 2004; Pospiškova et al. 2004; Bruce et al. 2010; Čortan et al. 2013, 2014; Maksimović et al. 2014). Existence of variability is a key factor in the process of species adapting to environmental changes. The higher variability exists there are higher chances for species long-term survival.
In order to develop strategies for conservation as well as for reforestation, it is necessary to estimate the amount and distribution of diversity in existing natural populations (Flush et al. 2002). Prescribing appropriate conservation