Effects of genetic entry and competition on above ground biomass production of Norway spruce grown in southern Finland

The effects of genetic entry and competition on the above ground dry biomass production (i.e. stem wood, needles, branches and harvest index) was studied in 20 Norway spruce (Picea abies (L.) Karst.) clones grown in southern Finland. Furthermore, the measured above ground biomass components were compared against the corresponding estimations based on biomass models developed previously. The clones included both Finnish and Russian clones, as well as provenance-hybrids clones. Differences existed between clones in stem dry mass production, but not in harvest index or in crown dry mass. However, the competition caused by neighboring trees also significantly affected above ground dry biomass, as well as the biomass of crown and stem separately. Differences in competition between the clones could not be found. Unlike the dry mass of branches, the dry mass of needles and stem could be estimated well for individual sample trees with the available biomass models. Moreover, the clone with the largest above ground dry biomass production had nearly doubled production, on average, than the average over all clones. Thus, some of the clones showed especially high potential for biomass recovery in energy wood thinning.