Relationships between environmental factors and height growth and yield of Norway spruce stands: a factor-analytic approach

Soil samples were taken from 148 experimental plots and subjectedto analysis of 34 morphological, physical and chemical properties.At the same time, eight climatic and topographic characteristicswere recorded. For each plot the values of top height and yieldwere available. The relationships between the soil propertiesand climatic/topographic characteristics were studied separately,for both sets of variables, by means of factor analysis. Theorthogonal varimax prerotation and the oblique promax rotationwere used. For soil characteristics, five common factors wereidentified, explaining 90 per cent of the total variance, relatedto soil acidity, water retention, humus content, nutrients andsoil texture. For climatic/topographic characteristics, threefactors were found, related to temperature, precipitation andterrain formation, explaining 85 per cent of variance. The relationships between the identified factors and heightgrowth and/or yield were quantified by polynomial regressionanalysis. Appropriate regression models were found for all factorsexcept the factor ‘nutrients’. Most regressionsproved to be non-linear. The applicability of the factor analysisfor determining the environmental factors is discussed.