The effects of temperature on competition for spruce needles among sympatric species of Trichoderma [Trichoderma hamatum, Trichoderma polysporum]

In a simple laboratory model system, the influence of temperature on the ability of 5 sympatric species of Trichoderma to compete for spruce litter (Picea abies) was studied. At temperatures of 5 C and 10 C, T. polysporum and T. viride were the best competitors, whereas at 15 C, 20 C, and 25 C, T. koningii and T. hamatum were best. These data agree with the known temperature preferences of these fungi in their natural habitat. Trichoderma sp. LP58, however, which is known as an abundant species during the summer in spruce forest soil, was not a good competitor against T. koningii or T. hamatum at high temperatures. The optimum growth temperatures for the species tested were higher than the maximum temperatures found in the soils from which they were isolated. The ability of the species to compete at a given temperature was often, but not always, a reflection of its growth in comparison to the other species at that temperature. The experimental data generally support the hypothesis that the ability of these species to form separate niches may be a result of differences in seasonality due to the influence of temperature on their ability to compete with one another.