Background and Objective

The most productive clones will be approved and recommende for planting in short rotation coppices.

Approach

After pre-testing in the nurseries the mots promising clones are propagated for establishment of stolbeds. Wooden cuttings of these clones are used for planting of up to 10 clone tests. After 3 to 5 years these trials will be harvested and the biomass will be assessed. Additionally resistance a gainst Melampsora leaf rust will be tested. Main goal is the selection of superior clones for short rotation plantations.

Results

Clones of the genus Populus, which were selected a long time ago for forestry purposes, only clone 960 (P. deltoides x P. maximowiczii) from Italy has proven itself without restriction on all test areas (5). Depending on the respective location and the rotation, yields of 7.5 and 23.0 t_oven-dry / ha / a were achieved. The clones 962 and H 275 (hybrid 275) showed good growth mostly. The other clones in this group only produced average or significantly below average yields. The performance of Max 1, which was used very often for short rotation coppices, was in the range of the respective trial means. The consistently poor performance of Androscoggin was surprising. This clone has also been used widely in recent years. The relatively poor rooting behavior of clones 960 and 962 is somewhat problematic. However, the initially lower number of plants is compensated for in later rotations by a higher growth rate per stock.

Some new clones from North America have also shown good yields after the 1st rotation. These are clones of both P. × euramericana and P. deltoides × P. maximowiczii. The yields of the best clones were between 7.5 and 23.0 t_oven-dry / ha / a.

The very strong dependence of the growth performance of all tested clones on the quality of the location was noticeable. Even small differences in micro-site conditions had an effect, as was proven by the high standard deviation ​​in the single tests.

In the case of willows, it is difficult to make a statement about the suitability of the tested clones for cultivation in energy wood plantations, since with one exception the yield level on the test areas was very low. If the site conditions are suitable for growing willows, good yields can be achieved with the Swedish clones Tordis and Sven, which can be over 10 t_oven-dry / ha / a after the second and third rotation. This is true also  to the clones SCUK, Reif and SN 2, which come from different species or hybrids.
For dry conditions, clones of Salix daphnoides may be of interest. This is especially true if multiple use is the objective, as this species is rich in salicylates.