Fungal communities in fallow soil before and after amending with pine sawdust

Pine sawdust (9 kg m−2) was ploughed into soils, intended for future forestry plantations, that had been left for 3 or 6 years after previously being used for agriculture. Two years after the amendment, soil pH had changed in both sites and the C:N ratio had increased. Total fungal populations decreased after the treatment. A small decrease in the number of species was not statistically significant. Trichoderma harzianum, an important biological control fungus, increased considerably after sawdust application whilst some fungi, such as Penicillium spp., Pseudogymnascus roseus and partially Mucorales decreased. The practical implications of the increase in T. harzianum density for the health of the young forests are discussed. © 2000 Elsevier Science B.V. All rights reserved.