Allometric Models of Foliage Biomass in Scots Pine (Pinus sylvestris L.)

摘要

Presented analyses were connected with modelling foliage biomass of Scots pine (Pinus sylvestris L.) growing in northern and western Poland. In order to realize the study, a total of 38 one-hectare experimental plots were established in commercial pine monocultures growing on sites optimal for this species at a given geographical location. A total of 114 trees aged 32-114 years were felled and their needle weight and the weight of needles and young, 1-year old twigs were measured. Since social variation in the stand could affect the fit of the model, for each social class of tree position an individual allometric equation was proposed, based on easily measurable biometric traits of trees. Analysis of stepwise backward regression was conducted in order to determine variables in these equations. It turned out that to estimate foliage biomass of predominant and dominant trees, it seems most appropriate to apply diameter at breast height and tree age. In turn, for co-dominant trees, apart from diameter at breast height and tree age, the model needs to include additionally tree height and crown length. Moreover, due to the fact that the dependence between needle weight and the weight of needles and young twigs is practically linear, prediction was conducted for the biomass of foliage with young twigs. From the practical point of view, this makes it possible to precisely determine needle biomass on the basis of the weight of needles with young, 1-year-old shoots.