Tree diameter measurements were made in 172 permanent research plots in pedunculate oak (Q. robur) stands, 202 plots
in birch (B. pubescens) stands, 325 plots in Monterrey pine (P. radiata) stands, 183 plots in maritime pine (P. pinaster) stands and 155 in Scots pine (P. sylvestris) stands inNWSpain (in the regions of Galicia and Asturias).