Prediction of Stem Properties Based on Climate and Soil Factors in Naturally Regenerated Pinus sylvestris Stands
This study aimed to investigate whether the number of stems per hectare with specific quality attributes could be predicted at a site that has been naturally regenerated with Scots pine (Pinus sylvestris L.) by evaluating site factors only. Factors related to climate (geographic location, growing season, temperature sum, humidity and frost frequency), soil properties (soil moisture, soil texture and depth of soil and humus layers) and site index were used for constructing models for predicting the number of stems per hectare that are straight, have no spike knots, have a maximum of two branches > 10 mm in the whorls, have no branch thicker than 15 mm and the thickest branch of which has an angle that is not acute. Models were constructed by projection to latent structures (PLS) modelling based on survey data from 24 stands in central and southern Sweden. Cross-validated models using climate factors alone or a combination of soil and climate factors explained 65–83% of the sum of squares in the quality attributes.