Fig. 4From: Effects of Quercus rubra L. on soil properties and humus forms in 50-year-old and 80-year-old forest stands of Lombardy plainBox plots for comparison of properties of organic and mineral layers between soil forest types (mixed forest, MF; red oak forest, ROF) at Bosco Ginestre (BG). Asterisk and plus sign indicate significant differences (p < 0.05 and p < 0.1, respectively) of response variable between forest types in the mixed modelBack to article page