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Background: Management practices can modify the productivity of forests and the associated microbial diversity of soil. The soil mycobiota is considered a key factor in the ecological functions of forests. Forests of Nothofagus pumilio (Poepp. & Endl.) Krasser (Nothofagaceae) are the main source of timber and one of the most important economic resources in the province of Tierra del Fuego (Argentina). However, there is no information on the impact of forest management interventions for the soil mycobiota, which can be reliable biological indicators of disturbance.Methods: Fungi were isolated from samples of soil collected under several Nothofagus pumilio forests subjected to different types of management and periods of time since the intervention. Types of management were represented by harvested forest with a shelter wood cutting, stockpile area and control forest without intervention and the periods of time since intervention were 1, 5–10 and 50 years. Species richness, evenness and Shannon’s diversity index of the mycobiota in each condition of management were calculated. Additionally, the effect of seasonality was analysed.Results: The soil mycobiota was represented by 70 taxa. Richness and/or Shannon’s diversity index of the mycobiota between undisturbed forest and stockpile area were higher in May (autumn) than in September or November. There were no differences in mycobiota diversity between dates in the harvested forest.Conclusions: Our results indicate that the forest intervention per se did not negatively affect the soil culturable mycobiota composition of N. pumilio forests in Tierra del Fuego (Argentina).

Background Nothofagus pumilio (Poepp & Endl.) Krasser, known as “lenga” is the most important timber wood species in southernmost Patagonia (Argentina). Humicolopsis cephalosporioides Cabral & Marchand is a soil fungus associated with Nothofagus pumilio forests, which has outstanding cellulolytic activity. However, there is no information about the ability of this fungus to use organic substrates other than cellulose, and its ability to produce different enzyme systems, as well as its response to temperature. Aims The aim of this study was to examine the role of H. cephalosporioides in degradation processes in N. pumilio forests in detail by evaluating the in vitro ability of four isolates of this fungus to grow and produce different lytic enzyme systems, and their response to incubation temperature. Methods The ability of the fungi to grow and produce enzyme systems was estimated by inoculating them on agar media with specific substrates, and the cultures were incubated at three temperatures. Results A differential behavior of each strain in levels of growth and enzyme activity was found according to the medium type and/or incubation temperature. Conclusions A intra-specific variability was found in H. cephalosporioides. Likewise a possible link between the saprotrophic role of this fungus in N. pumilio forests and the degradation of organic matter under stress conditions, such as those from frosty environments, was also discussed. Antecedentes Nothofagus pumilio (Poepp & Endl) Krasser (N. pumilio), conocido como «lenga», es la especie maderable más importante en el extremo sur de Patagonia (Argentina). Humicolopsis cephalosporioides Cabral & Marchand es un hongo del suelo asociado a bosques de N. pumilio, que tiene una actividad celulolítica excepcional. Sin embargo, no hay información acerca de la capacidad de este hongo para utilizar otros sustratos orgánicos distintos de la celulosa, o para producir diferentes sistemas enzimáticos, así como su respuesta a la temperatura. Objetivos El objetivo de este estudio fue profundizar en el rol que Humicolopsis cephalosporioides tiene en los procesos de degradación en los bosques de N. pumilio a través de la evaluación de la capacidad in vitro de 4 aislamientos de este hongo para crecer y producir diferentes sistemas enzimáticos líticos y su respuesta a la temperatura de incubación. Métodos La capacidad de los hongos para crecer y producir sistemas enzimáticos se estimó a través de su inoculación sobre medios de agar con sustratos específicos, siendo incubados a 3 temperaturas. Resultados Se observó un comportamiento diferencial de cada cepa en el crecimiento y la actividad enzimática de acuerdo con el tipo de medio o la temperatura de incubación. Conclusiones Se observó variabilidad intraespecífica en Humicolopsis cephalosporioides. Asimismo, se discutió la posible relación entre el rol saprotrófico de este hongo en los bosques de N. pumilio y la degradación de la materia orgánica en condiciones estresantes, como las existentes en ambientes fríos. Fil: Eliades, Lorena Alejandra. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina Fil: Cabello, Marta N.. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina Fil: Pancotto, Veronica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Moretto, Alicia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Rago, María Melisa. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina Fil: Saparrat, Mario Carlos Nazareno. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Fisiología Vegetal; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina