Site factors and variables that best explain productivity variability were determined for sites with adult Pinus radiata plantations. The study covered 70 sites in Central Chile (33°-41° S) with great climate and soil variations.
Through correlation analysis, step-wise and linear regression, climate stood out as the main factor of productivity variability. According to this result, the need to analyze sites with sandy soils separately from those with non-sandy soils became evident. The water regime, through the soil physical and climatic variables, was shown have the greatest effect upon productivity; the regime of soil nutrients was shown to have a lesser effect.