Interactions among five species of Trichoderma were investigated in the laboratory in order to determine whether temperature affected the ability of species to survive on spruce litter in the face of competition from other Trichodermas. Ability of these species to inhibit the growth of competitors was also tested under a range of temperature regimes. Data showed that, in general, T. hamatum, T. koningii and isolate LP58 were more aggressive and less subject to displacement than were T. viride and T. polysporum. All species tested were antagonistic towards each other and towards Botrytis cinerea, but no marked effects of temperature were observed on antagonistic activity. Displacement experiments, however, showed that T. viride and T. polysporum survived better at lower temperatures. These data are discussed in relation to ecological strategies of Trichoderma species. It is suggested that Trichoderma species, though exhibiting some ruderal properties, should more properly be considered as exhibiting a competive strategy. Within the genus, it is also suggested that t. polysporum and T. viride are showing stress-tolerant characteristics.
