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ŠUMARSKI LIST 3-4/2013 str. 37     <-- 37 -->        PDF

The regeneration of pure Juniperus excelsa M. Bieb. stands in Prespa National Park in Greece
Regeneracija šuma Juniperus excelsa M. Bieb. u nacionalnom parku Prespa u Grčkoj
Juniperus excelsa M. Bieb is a species with growth plasticity that is capable of growing in harsh abiotic environments as well as in severe biotic conditions. In order to analyze the regeneration of J. excelsa pure stands in Prespa National Park of Greece and to determine whether regeneration in gaps or under facilitation of nurse plants dominates, ninety sample plots were established in two site types and six structural types. In each plot, all J. excelsa regeneration plants were graded in 2 categories. The first category represents the seedlings that have been established and grew under the facilitation of other plants, while the second category refers to seedlings that are found in canopy gaps without significant side shade. Facilitation does not dominate in the regeneration process of J. excelsa in Prespa National Park. On the other hand, this does not mean that regeneration in gaps predominates. Even though facilitation is not the dominant process in the regeneration of J. excelsa in Prespa National Park, a significant number of regeneration plants have been established under the facilitation. Site productivity seems to affect the process of facilitation. It seems that the process of grazing through trampling and animal tread determines the regeneration process of the species that can be established and grow either in light or under shade. J. excelsa can be a very interesting candidate species for restoration of degraded lands.
Key words: Juniperus excelsa, regeneration, facilitation, nurse plants, gap
Juniperus excelsa M. Bieb. usually appears in mountainous areas (Hall 1984; Ahmed et al. 1990; Fisher and Gardner 1995; Gardner and Fisher 1996; Ravanbakhsh et al. 2010; Stampoulidis and Milios 2010; Douaihy et al. 2011; Milios et al. 2011). Even when it is found in an elevation of few tens of meters, in Greece, the topographic relief is mountainous (personal observation). J. excelsa is a species of southeastern Europe that is also apparent in Crimea, Anatolia, southwest and central Asia as well as east Africa (Athanasiadis 1986; Boratynsky et al. 1992; Christensen 1997).
J. excelsa exhibits growth plasticity and can adapt and grow in diverse growth regimes (shade – light), while, in favorable conditions, it is able to increase its growth rates even at old ages (Milios et al. 2009). Moreover J. excelsa is capable of growing in harsh abiotic environments (shallow and stony soils, cold, hot and dry climates) as well as in severe biotic conditions like grazed sites (Hall 1984; Ahmed et al. 1989, 1990; Fisher and Gardner 1995; Gardner and Fisher