In Chile there are few studies describing the biological activities and soil nutrient dynamics in high mountain areas, therefore sensitive parameters able to express what happens in these ecosystems are required. The aim of this study was to determine soil biological properties through biochemical variables: fluorescein diacetate hydrolysis, carbon and nitrogen microbial biomass, β-glucosidase, carboximethylcellulase, acid phosphatase, urease and arylsulfatase; and chemical characteristics of soil in an altitudinal transect in Conguillío National Park (38º S), Chile. We investigated four forest communities from 1,140 to 1,700 m a.s.l.: Nothofagus antarctica, Nothofagus alpina with Nothofagus dombeyi, Araucaria araucana with Nothofagus pumilio and Nothofagus pumilio (Krummholz). Biochemical parameters were sensitive to changes in altitude, obtaining the highest biological activities (fluorescein diacetate hydrolysis, nitrogen microbial biomass, acid phosphatase, β-glucosidase) in N. alpina with N. dombeyi (74.9 μg fluorescein g^-1 h^-1; 50.3 mg N kg^-1; 78.8 μmol p-nitrophenol g^-1 h^-1; 9.14 μmol p-nitrophenol g^-1 h^-1, respectively) located at 1,250 m a.s.l. due to favorable climatic conditions, followed by N. antarctica and A. araucana with N. pumilio. The lowest levels of the biological activities are shown by N. pumilio (Krummholz) (23.7 μg fluorescein g^-1 h^-1; 3.1 mg N kg^-1; 6.2 μmol p-nitrophenol g^-1 h^-1; 0.78 μmol p-nitrophenol g^-1 h^-1, respectively) at 1,700 m a.s.l., located in restricted soil and climatic conditions.