DIGITALNA ARHIVA ŠUMARSKOG LISTA
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increasing rates. The mean CSG with the 2, 3, and 5% herbicide rates was 22, 44, and 64%, respectively, compared to that of the control seeds and was lower by the end of the experiment (Table 1). The herbicide rate also had a similar effect on the germination speed (Fig. 1). Scots pine – Bijeli bor Germination started on Day 4, and more than two-thirds of the control seeds had germinated by the second week, demonstrating a higher speed of germination than black pine (Table 1, Fig. 1). Similar to black pine, Scots pine seeds were not significantly sensitive to clopyralid at rates of ≤1.5%; however, herbicide phytotoxicity increasingly intensified with higher rates. Increasing the herbicide rate to 2, 3, and 5% significantly brought about 21, 39, and 63% decreases, respectively, in the mean CSG when compared to the control seeds. Germination speed progressively decreased in parallel with the increasing herbicide rate (Fig. 1). Turkish red pine – Brucijski bor (TRP) Similar to maritime pine, TRP exhibited no seed germination by the second week of the germination test, whereas at the end of the second week of the experiment demonstrated the greatest CSG performance among all of the pine species including the control seeds (Table 1). Unlike the rest of the analyzed pine species, TRP began to demonstrate substantial clopyralid sensitivity at a lower rate (1.5%), and this sensitivity increased more at higher herbicide rates. The mean CSG at 2, 3, and 5% herbicide rates decreased by 12, 32, and 57%, respectively, when compared to that of the control seeds. The effect of clopyralid on the germination speed of TRP was comparable to that seen in the other pine species (Fig. 1). DISCUSSION RASPRAVA Most of the distribution area of black, maritime, Scots, and TRP is subject to site degradation with the existence of a high level of environmental (e.g., drought, erosion) and anthropogenic pressure (Genç 2012; Boydak and Çalışkan 2014; Yildiz et al. 2018). Because they provide more favorable site conditions, “microsites” that are dispersed on degraded areas can offer stressed vegetation essential resources and can substantially enhance plant establishment. By supplementing natural seed dispersal and uniting seeds via these microsites, direct seeding can dramatically improve tree seedling survival and growth on such stressed areas (Dixon et al. 2005; Doust et al. 2006; Jinks et al. 2006; Greipsson 2012; Löf et al. 2016; Grossnickle and Ivetić, 2017). On the other hand, weeds that usurp essential site resources (i.e., water and nutrients in the soil) can pose a great threat to the establishment of crops in these already |