Long-Term Testing of Aspen Clones in European Russia

The results of 40 years of testing of more than 20 aspen clones selected in various regions of European Russia and the USSR, growing in the Semiluki Tremuletum in the Voronezh Region, are presented. The survival of plants, growth in height, diameter and volume of the stem are shown. A ranked assessment has been given and a selection of promising clones for the creation of highly productive aspen plantations has been carried out. It has also been noted that sexual dimorphism can have different effects on aspen rot resistance in different growing conditions. The testing has been conducted at the Central Research Institute of Forest Genetics and Breeding (currently the All-Russian Research Institute of Forest Genetics, Breeding and Biotechnology). A number of employees of the Institute have been engaged in the selection of the best forms, and then in hybridization, since its organization in 1971. The aim of this study has been to investigate the survival and growth of 21 long-lived aspen clones, as well as their productivity (in terms of stem volume), growing in the Semiluki Tremuletum of the Voronezh Region. It has been revealed that the height variation at the age of 40 has been quite wide – from 17.3 to 31.3 m, diameters – from 28.0 to 50.0 cm, stem volumes – from 0.3 to 2.4 m3. The top 5 has included 2 aspen clones from the Botanical Garden of the Voronezh State University (clones no. 16 and 17), 2 hybrids introduced from the Baltic States (clones no. 20, 23) and American aspen (clone no. 29). Their average height at the age of 40 has been 26–31 m, diameter – 42–50 cm, stem volume – 1.4–2.4 m3. This indicates the possibility of selecting promising aspen clones for their further propagation and introduction into plantation forest cultivation. At the same time, male clones (Pzg hybrid and American aspen clone no. 29), also introduced from the Baltic States, can be recommended for landscaping.