Thermal and aeration properties of mor layers in Finland

Thermal conductivity (K-T), air permeability (K-a) and relative diffusivity of oxygen (ratio of oxygen diffusion coefficient in the soil to the oxygen diffusion coefficient in free air, D/D-0) were measured from undisturbed m or samples taken from low-fertility (CT) Scots pine (Pinus sylvestris L.) s ites and medium-fertility (MT) Norway spruce (Picea abies (L.) Karst.) site s. K-T was determined with respect to matric potential (psi), whereas K-a a nd D/D-0 were determined as a function of air-filled porosity (epsilon (A)) . K-T(psi) and D/D-0(epsilon (A)) were slightly greater on the MT sites tha n on the CT sites, whereas K-a(epsilon (A)) did not differ statistically be tween the site types studied. K-T(psi) and K-a(epsilon (A)) were similar to those values reported in the literature for other organic soils, but D/D-0 (epsilon (A)) was slightly lower. Among the MT sites, the parameters for th e K-T(psi), K-a(epsilon (A)) and D/D-0(epsilon (A)) models correlated with the water-retention characteristics. Among the CT sites, the parameters for K-a(epsilon (A)) and D/D-0(epsilon (A)) models correlated with bulk densit y, layer thickness and distance from the nearest trees.