Resumen

GOMEZ, Yrma; PAOLINI, Jorge  y  HERNANDEZ, R. M.. The substitution of native savanna by pine plantations, and the temporal variability in microbial biomass and carbon and nitrogen mineralization. Terra Latinoam [online]. 2010, vol.28, n.2, pp.155-163. ISSN 2395-8030.

Land use change and the temporal variability characteristic of the eastern plains of Venezuela are factors that have ecological impact on populations and microbial activities. Specifically, in this region, a large extension of native savanna has been replaced by plantations of Pinus caribaea var. hondurensis; however, little is known about the impact that this land use change produces in the quality of these soils. This study investigates the magnitude in which the microbial biomass and the parameters involved in the carbon (C) and nitrogen (N) mineralization activities are affected by land use change and temporal variability. The study was conducted during the dry and rainy periods. Microbial biomass was determined through the fumigation-extraction method (FE). Carbon mineralization activity was measured by determining the β-glucosidase activity and N mineralization through arginine ammonification (AA) and protease-Nα-benzoyl-L-arginamide activity (protease-BAA).The results showed that these parameters are indicators of changes in soil quality. Land use change affected the microbial biomass and C and N mineralization rate. The higher microbial biomass in the pine plantation, as well as the lower C and N mineralization activity in this plantation, suggests that more of these nutrients are preserved in pine plantations, improving soil quality. The temporal dynamics of microbial biomass in the native savanna and in the pine plantation is not related to the temporal variability of C and N mineralization of these systems.

Palabras llave : arginine amonification; β-glucosidase; microbial carbon; microbial nitrogen; protease-BAA.

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