No abstract

Slovakia is acountry with limited natural resources, therefore its essential task is to search for new renewable sources of energy to reduce its dependence on imported fossil fuels. The results of research confirmed that the Common Reed (Phragmites australis(Cav.) Trin.) has considerable potential of phytomass production and energy storage (calorific value reached 17,448 J g−1d.w.). Biomass production of Common Reed under natural conditions of the lower Liptov region reached 12.702 tons of a dry mater per hectare with the calculated energy storage of 221.622 GJ ha−1. The average biogas production was 351.31 l kg−1of a dry matter of which the methane (CH4) content represents 185.21 l kg−1(52.72%). With regards to the values of combustion heat, a calorific value and the production of methane it can also be noted that in case of Common Reed it is more profitable to focus on direct combustion of biomass than the production of biogas and methane.

Ecology of capercaillie (Tetrao urogallus) was studied in the mountains of Central Slovakia (West Carpathians) in 1981-2003. In the studied area, the capercaillie population inhabited especially old natural forests (100-250 years old) in the spruce-beech-fir (850-1,270 m a.s.l.) and spruce (1,250-1,530 m a.s.l.) vegetation zones. The overstorey stand age ranged between 80 and 250 years with the mean of 128 years. The understorey stand age ranged from 10 to 60 years. The overstorey tree density ranged between 200 and 1,050 stems per ha (mean 725). The understorey tree density ranged from 5 to 650 trees per ha (mean 290). Both males and females preferred old forests throughout the year. The results demonstrate a marked decrease (> 50%) in the numbers of cocks and hens on twelve monitored leks (28%) and a slight decrease (< 50%) on ten display grounds (24%). During the study period, capercaillie cocks became extinct on seven (16%) leks and in their surroundings. More or less constant numbers were found on twelve leks only (28%) and a slight increase occurred on two leks only (4%). A statistically highly significant correlation was found between the area of old-growth forest and the number of cocks attending a lek. In addition to forest deterioration predation appeared to be of major importance in limiting the numbers of capercaillies. Key points for forest management in relation to capercaillie protection are suggested.

The box tree moth Cydalima perspectalis is an invasive pest on box trees originating from Eastern Asia which spread throughout Europe. We assessed the efficacy of photo-eclectors (emergence boxes) for the detection of its larvae. We also investigated their spatial distribution on the hosts and the spatial and temporal distribution of the leaf damage caused by this pest in Slovakia. Our results showed non-uniform vertical distribution of the overwintering larvae and leaf damage on the trees. The larval abundance in the spring was significantly affected by the height of the branches above the ground. During spring, the larvae occurred most abundantly in the upper parts of the trees. The leaf damage was greatest in the lower parts throughout the growing season. During the progress of the infestation, the development of the damage in the lower and middle parts was similar. In the upper part, the initial increase in the damage was slow, but accelerated four months before the complete defoliation. The field estimation of the proportion of damaged leaves and the accurate assessment based on counting the damaged leaves suggest a consis­tency between these estimates. Hence, a quick field estimation of the leaf damage may be utilised by horticultural practices.