Resumo

DEFRIERI, Rl; EFFRON, D; JIMENEZ, MP  e  PRAUSE, J. Influence of tree species on the activity of acid phosphatase and protease in a forest soil. Cienc. suelo [online]. 2008, vol.26, n.2, pp.177-182. ISSN 1850-2067.

Plant cover and especially the dominant tree species affect biological and chemical properties of the soil. Litter decomposition rate is affected by its N and P concentration. The aim of this work was to determine the different effects of forest tree species on some biochemical properties of the soil. The study site was located at the Reserva Natural Estricta Colonia Benítez, Chaco, Argentina. Soil samples were taken under trees of the four dominant species in the area and at two depths (0-10 cm and 10-20cm) and moments: in summer and in winter. Activities of acid phosphatase and protease enzymes and some edaphic parameters were determined. The results obtained for all studied variables were significantly lower at the 10-20 cm depth, for all forest species and in both seasons. Values of enzyme activities showed significant differences between species only in surface samples where the incorporation of organic matter is greater and in summer. In these conditions, the values of enzymatic activities obtained in soils under each species ranged between 1,600 and 900 μg p-nitrophenol g^-1 h^-1 for acid phosphatase and between 850 y 450 g tyrosine g^-1h^-1 for protease. For two of the studied species, a relationship was found between the amount of litter produced, the different decomposition rates and the N and P concentrations in senescent leaves with the enzyme activities in soils. Inorganic N and available P concentrations in soils did not show significant differences between species. In this study, soil enzyme activities were more related to the overlying species than some measured soil parameters.

Palavras-chave : Forest soil; Forest tree species; Acid phosphatase; Protease.

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