Influence of lammas shoots on productivity of Norway spruce in Latvia
¹Latvian State Forest Institute ‘Silava’, Rigas 111, LV2169 Salaspils, Latvia
²Latvia University of Agriculture, Forest Faculty, Akademijas 11, LV3001 Jelgava ,Latvia
³Forest Competence Centre, Dzerbenes 27, LV1006 Riga, Latvia *Correspondence: email@example.com
The Norway spruce is widely spread in Eastern Europe and it is managed mainly for the production of sawlogs, though its logging residues are now increasingly used for the production of wood chips for bioenergy. The growth of the Norway spruce is and will be affected by climatic changes; one of the possible effects might be an increase in the frequency of trees with lammas shoots. Therefore, the aim of this study was to assess the influence of lammas shoots on the length of height increment of young Norway spruce in Latvia. Tree height and height increment was repeatedly measured and the presence of lammas shoots, bud flushing grades and frost injuries were assessed in two young (8–13 years) open-pollinated progeny tests in the central part of Latvia (56°46´N, 24°48´E). The mean portion of trees with lammas shoots in one experiment was 6% at the end of 8th growing season. In another experiment, it was 8.7%, 26.9% and 8.1% at the end of 10th, 11th and 13th growing seasons, respectively; 32.3% of trees had lammas shoots at least in one of three seasons. Faster growing and earlier flushing trees had a significantly higher frequency of lammas shoots. Lammas shoots increased the length of annual height increment by 10 to 14 cm, resulting in a 14–20% taller tree height at the age of 13 years. The reduction of height increment as a result of frost damages for very early flushing trees was less pronounced for trees with lammas shoots than without them.