Assessment of the Quality and Productivity of Lodgepole Pine Grown in the Western Part of Latvia

Abstract

The research aims to examine the pace of growth of lodgepole pine, the amount of damage caused by biungulates and the quality of trunks for lodgepole pine provenances growing in the western part of Latvia in the areas around Ugale and Kuldiga, identifying the most damage-resistant and promising provenances for cultivation in Latvia. In Latvia, foresters and plant breeders have been working for years to increase the quality and productivity of local tree species, while assessing various forest stand management patterns and trying to reduce the rotation period of stands. Nowadays, because of climate change, i.e. with the climate becoming warmer, it is clear that in the future in Latvia not only a management strategy for the dominant tree species have to be changed but also the possibilities of introducing new tree species suitable for the conditions in Latvia need to be considered to reduce the forest rotation period. At the same time, introducing new tree species requires considering that the tree species must have economic potential, i.e. the wood has prospects for being processed and consumed (e.g. construction) in the local region, as carbon is sequestrated during the growth of the trees and stays in Latvia. Lodgepole pine is one of the tree species that could have prospects for cultivation on an industrial scale in plantations, which was introduced in Latvia at the beginning of the last century. Based on the experience of Swedish foresters in growing lodgepole pine on an industrial scale in the 1980s, experimental lodgepole pine plantations were established in Latvia by using both domestic seeds and those from the natural range in Canada and the United States, as well as from Sweden. The research analysed the following tree inventory data collected from the experimental plantations of lodgepole pines at the ages of 27 and 43 years in the western part of Latvia: the height and diameter of the trees and compared the data for Scots pine grown in identical conditions. In addition, the proportions of trees damaged by deer etc. as well as the proportions of trees with multiple tops and branch-to-stem attachments because these defects significantly reduce the chances of producing quality roundwood assortments in the future were analysed for both species. The data were processed using parametric methods. In an experimental plantation in the area near Ugale, 43-year-old lodgepole pines demonstrated a performance similar to that of Scots pines, with average heights of 18.2 and 18.4 meters and diameters of 19.1 and 19.0 cm, respectively, i.e. the differences were insignificant. In the plantation near Kuldiga, the differences were found significant, as the average height difference between the species was 1.3 m, while the diameter difference was 1.3 cm. It was concluded that lodgepole pines had lower trunk quality and were more damaged by deer. It was also found that the least productive lodgepole pine provenances were more damaged by deer.