Microhabitat characterization of Trichoderma harzianum in natural soil: Evaluation of factors affecting population density

A study on the ecology of Trichoderma harzianum in soil evaluated the importance of 54 factors, measured from 50 mg soil samples, with respect to the population densities of T. harzianum in the soil microsites where it was present. The significance of nine abiotic factors, total bacterial, fungal and actinomycete populations, and the presence of 42 different fungi were determined with the use of multiple linear regression analysis. T. harzianum densities were found to be highest during the wet winter months, with a second peak during the early summer. T. harzianum densities were also positively correlated with total bacterial populations and soil moisture content. Sampling depth, and the presences of Chaetomium sp., Penicillium miczynskii, Scolecobasidium variabile, Ulocladium atrum and Verticillium nubilum were all found to be negatively correlated with the density of T. harzianum. Several of the factors found to be important to the density of T. harzianum were not important to the establishment of the fungus in the soil microsites.