Resumo

PASTOR MOGOLLON, José  e  MARTINEZ, Alicia. Variation of soil biological activity in an altitudinal transect of la sierra de San Luis, Falcon state. Agronomía Trop. [online]. 2009, vol.59, n.4, pp.469-479. ISSN 0002-192X.

The objective of this paper is to study the variation that exists in the biological activity of the soil in an altitudinal transect, product of changes associated to the vegetation, and precipitation levels in each one of the points of the gradient. The soil biological activity was quantified through the soil basal respiration, the microbial biomass carbon, and the urease activity. Six sites of sampling were selected along the transect La Chapa-Curimagua, of “Sierra de San Luis”, Falcon State. The sampling sites were the following ones: La Chapa to 720 m a.s.l.; San Diego to 1.000 m.a.s.l.; Santa Lucia to 1.100 m a.s.l.; El Palenque to 1.200 m.a.s.l.; Macanillas (M) to 1.320 m a.s.l., and Cerro Galicia (CG) to 1.400 m a.s.l. In each one of these sites, six composite soil samples were collected, to a depth of 0-10 cm. The greater soil basal respiration was observed in CG and M with values of 23.8 and 18.3 μg C-CO2 g^-1 soil h^-1, respectively. The soil microbial biomass had a rank from 739 to 2.849 μg Cmic g^-1, being the greater values, in the sites of greater altitude. With respect to the soil urease activity, this displayed the same tendency of the previous parameters, being observed the greater enzyme activity in M (160.30 μg NH4 g^-1 soil 2h^-1), and the lowest values in LC (14.71 μg NH4 g^-1 soil 2h^-1). The content of organic carbon in soil studied, as well as the soil biological activity, is influenced by changes in the vegetation and changes in the precipitation patterns

Palavras-chave : Urease activity; edaphic respiration; microbial biomass; altitudinal gradient.