Figure 2. Pore size distribution of beech wood biochar as determined by scanning electron microscopy.

In total, mean diameters of 7715 pores were measured in 6 longitudinal and 7 cross sections of charcoal pieces, each image covering 0.35 mm². Pore size distributions are presented (1, top panel) as counts mm⁻² per 1 µm size class (top) and (2, middle panel) on an area basis, i.e. µm² mm⁻² per 1 µm size class. Typical mean diameters (soil bacteria, soil fungi) and diameter ranges (arbuscular mycorrhizal fungi; protozoan grazers such as flagellates, amoebae, ciliates; and mesofaunal grazers and predators such as nematodes, mites and collembola) are presented color-coded (bottom panel) and with range lines in the middle panel.