Basic density and crown parameters of forest forming species within Steppe zone in Ukraine

The parameters of wood density (WD), bark density (BD) and tree crown characteristics are not only important for estimation of the aboveground biomass, but they also serve as indicators for the timber quality. This study had two objectives: Black locust (Robinia pseudoacacia L.) – an introduced species; Scots pine (Pinus sylvestris L.) – an aboriginal species. Black locust and Scots pine from the Steppe zone in Ukraine were compared in their WD and BD, and in the morphological parameters of their tree crowns. There were determined basic WD and BD for differently aged individuals of Black locust and Scots pine. Generally, a higher WD was found for Black locust trees. The average Black locust WD was 518 kg m−3, ranging from 375 kg m−3 to 612 kg m−3; with the average BD – 294 kg m−3, ranging from 214 kg m−3 to 421 kg m−3. The average Scots pine WD was 414 kg m−3, ranging from 254 to 491 kg m−3; with average BD – 317 kg m−3, ranging from 178 to 433 kg m−3. The dependences between WD, BD and biometric tree parameters were identified by correlation analysis. The crown diameter for Black locust and Scots pine was described with fixed prediction models. We proposed particular equations for relationships between foliage biomass and branch biomass, derived from the crown volume of the investigated species.