Comparison of the growth of the provenances of silver fir (Abies alba Mill.) on research plots in the regions Novohradské hory and Českomoravská vrchovina at the age of 50 years

The study evaluates the results of a long-term research trial lasting 50 years in two research plots established in the 1970s aimed at solving the decline of the silver fir in the Czech Republic. A total of 103 different provenances occurring naturally across 12 countries were planted in research plots No. 67, Černovice (Českomoravská vrchovina), and No. 77, Nové Hrady (Novohradské hory). The total tree height, diameter at breast height (DBH) and assessment of the health status of all trees in the area were measured with the same methodology. Subsequently, the volume of large wood was calculated by the volume equation, and the growing stock per hectare was recalculated. Based on our analysis of average height growth, it was found that trees with the best growth came from provenances that included the Czech provenances CZ 70 - Ždírec nad Doubravou, CZ 82 - Vizovice, CZ 42 - Lukov, CZ 76 - Nýrsko, Suchý Kámen, and CZ 53 - Opočno. The last three mentioned provenances also dominated in other growth parameters (DBH and volume of large wood). Of the foreign provenances, D 146 - Schwarzwald mit Baar, S 9 - Kriváň, and S 6 - Čierny Váh produced trees that showed above-average values. The smallest growth in height was found in the trees from the provenances BG 132 - Rila, Borovets, F 104 - Departement de ľ Aude, I 228 - Vallombrosa, A 93 - Wörschachwald. Although some trees of Italian provenance achieve above-average volume, due to high mortality, they are not suitable for economic use in the forests of the Czech Republic. Based on the European zoning for forests, the units from the Central European region (3.11.0 - České Polabí, 3.32.0 - Schwarzwald with foothills and Baar, and 9.14.0 - Southern Apennine Mountains) were the best rated in all parameters. Specimens from 9.12.0 - Mountain forest of the northern Apennines, and 4.05.0 - Vosges showed the lowest parameters.