Productivity of poplar hybrid (Populus balsamifera x P. laurifolia) in Latvia
Latvian State Forest Research Institute ‘Silava’, Rigas 111, LV-2169 Salaspils, Latvia; *Correspondence: email@example.com
Fast growing poplar clones have been widely used for biomass production in Southern Europe; however, there is insufficient information about the growth of poplar in north-eastern Europe that might hamper its wider use. The aim of the study was to assess the productivity of poplar hybrid and its potential for biomass productions. Material for the study was collected in 14 stands (age 54–65 years) located in the central and western part of Latvia (56–57°N, 22–23°E), which were established on fertile drained mineral soil (Mercurialiosa mel.) and mineral soil with normal moisture regime (Oxalidosa and Aegopodiosa). Tree diameter and height were measured and biomass was estimated using equation developed based on 24 sample trees. Mean tree diameter and height in stands on mineral soil varied greatly (from 29 ± 1.6 cm to 45 ± 3.9 cm and from 24 ± 0.9 m to 31 ± 0.8 m, respectively); however in stands on drained mineral soil mean diameter and height was 42 ± 2.1 cm and 27 ± 0.7 m, respectively. Mean diameter and height of poplar was 16.7–25.1% higher compared with Norway spruce and these differences were statistically significant (p-value < 0.05), differences with common aspen were not significant. The number of fallen and standing dead trees, reaching up to 14–46% from the number of living trees, indicated aging and intense self-thinning. Mean annual volume increment of all stands was 11.8 m3 ha-1 y-1 (in some of stands reaching 21.0 m3 ha-1 y-1), corresponding to 4.2–9.8 t of dry matter per year. Thus, the results suggest that poplar could be an efficient species for production of bioenergy.