DIGITALNA ARHIVA ŠUMARSKOG LISTA
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can be attributed to the inital values of DBHs. The relationship between the trees’ PAI (basal area and volume) and their corresponding basal area and volume values is even better described by the linear regression model where 68.3–70.7% of variability can be attributed to their initial values. The trees’ height PAI was not correlated to their initial values at age 11 years. However, the change of h/DBH in the period from age 11–16 years has a pronounced negative linear trend — the trees with higher h/DBH at age 11 years had a more pronounced decrease (Table 8). Discussion and conclusions Rasprava i zaključci Italian alder was recently introduced to Serbia and reported in a linear plantation at Fruška Gora (Bobinac et al., 2015a). The first results of growing Italian alder in the linear plantation showed that the top height was 14.6 m and dominant diameter 32.1 cm at 11 years of age (Bobinac et al., 2015b). The values for Hdom of 21.0 m, Ddom of 59.4 cm and height and diameter PAI (1.2 m∙year−1 and 5.4 cm∙year−1) at age 16 years show that the species grows rapidly. Basal area of nearly 35 m2·ha−1 and volume of the plantation of over 300 m3∙ha−1 show that the plantation is very productive in researched conditions. Mean height of 9.9–10.4 m and mean DBH of 15.1–16.4 cm were measured in a pastoral system with A. cordata in New Zealand, at 3 × 4 m spacing, at age 11 years (Devkota et al., 2009). According to Praciak et al. (2013), in the coppice stands (15–20 years rotation) of the most productive region of Italy, the highest recorded mean annual increment is 16 m3∙ha−1 (12–13m3∙ha−1on average). However, a wide spacing of 7 m allows the trees to use large growing space, therefore more light and soil compared to different forms of plantations in the same spacing. The calculated volume and volume PAI are thus only approximate, therefore representing the potential of the species (Table 1 and 6). The trees have large leaf area due to crown length. In this plantation, the leaves keep green colour until the fall (end of November), or even until the middle of December in some years (Figure 4) so this trait represent an asset for high increment values at 7 m spacing. The long retention of leaves, until the November or December was described by Praciak et al. (2013) as well. Vitality assessment and growth characteristics of trees at age 11 and 16 years in the plantation show that the species is characterised by rapid growth, similar to poplars. In a |