DIGITALNA ARHIVA ŠUMARSKOG LISTA
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|ŠUMARSKI LIST 5-6/2014 str. 45 <-- 45 --> PDF|
thermometers (T-buttons, Dallas Semioconductor, USA; accuracy 0.1°C, 0.1%), which record the soil temperature every 30 minutes.
Evaluation of crown defoliation – Procjena defolijacije u krošnjama
In the autumn of 2009, six circular plots (50 x 50 m each) were defined within the most highly infested area. On each of the plots, tree species whose diameter at breast height was over 10 cm were inventoried. The defoliation of the crowns of conifer trees was then estimated, which is a basic indicator for assessing the vitality of trees. This indicator expresses a visually estimated proportion of the missing assimilation organs of the selected tree compared with individuals of the same species and social class that were found on the same site but exhibited normal foliage (Kovač et al. 2007). The evaluation of crown defoliation was repeated in 2010.
In 2012, we identified the species C. arvensis. Males were dominant, as they comprised 89% of the total. Comparing specimens caught in Slovenia with specimens caught in Italy, we observed a difference in colour; the population from Slovenia had markedly darker patterns compared to the population from Italy (Figure 1, 2, 3).
Darker coloration also occurs in the species C. alpina and C. annulicornis, but, with precise identification, the presence of these two species was excluded. It might be that C. arvensis was the dominant species at the Prevalje location. Due to the damages and characteristics of the older larvae and prepupae, we could conclude that C. abietis was also present. Molecular study would give more data concerning the identification of Cephalcia species. Problem is, that in the base of sequences (GenBank base), there is no reference sequence down to the species level.
Species determination on the basis of prepupae was performed on 147 specimens. Of the sample, 71% matched the description of the prepupae of C. arvensis; the remaining 29% represented other species of the genus Cephalcia or the species could not be determined due to unclear patterns.