Biomass production of young lodgepole pine (Pinus contorta var. latifolia) stands in Latvia

Biomass as a source of renewable energy is gaining an increasing importance in the context of emission targets set by the European Union. Large areas of abandoned agricultural land with different soils are potentially available for establishment of biomass plantations in the Baltic states. Considering soil and climatic requirements as well as traits characteristic for lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm) and the scarcity of published knowledge, we assessed the above-ground biomass of Pinus contorta in comparison to that of native Scots pine (Pinus sylvestris L.) and factors affecting biomass production. Data were collected in 3 experimental trials, located in two sites in central part of Latvia: Zvirgzde and Kuldiga (56°41’ N, 24°28’ E and 57°03’ N, 21°57’ E, respectively). Trials were established with density 5000 tree ha-1, using seed material from Canada (50°08’-60°15’ N, 116°25’-132°50’ W) and two Pinus contorta stands with unknown origin growing in Latvia. Results reveal that absolute dry aboveground biomass of Pinus contorta reaches 114 ± 6.4 t ha-1 at age 16 on a fertile former arable land, 48 ± 3.6 and 94 ± 9.4 t ha-1 at age 22 and 25, respectively, on a sandy forest land (Vacciniosa forest type). The biomass is significantly (p < 0.01) and considerably (more than two-fold) higher than that of the native Pinus sylvestris and the productivity is similar (in fertile soils) or higher (on poor soils) than reported for other species in energy-wood plantations. Provenance was a significant factor affecting the above-ground biomass, and the ranking of provenances did not change significantly between different soil conditions. It provides opportunities for further improvement of productivity using selection.