IMPACTO DE LA DENSIDAD DE GATUÑO (MIMOSA MONANCISTRA) EN LA MICROFLORA DE SUELOS DEL SEMIÁRIDO DEL ESTADO DE AGUASCALIENTES IMPACT OF THE DENSITY OF CATCLAW (MIMOSA MONANCISTRA) ON THE MICROFLORA OF SEMIARID SOILS FROM AGUASCALIENTES

SUMMARY The impact of different densities of a native shrub legume known as cat claw (Mimosa monancistra) was determine, over the abundance and activity of the microbial flora located in and out side the canopy. Such impact was determine by means of the carbon content of microbial biomass, total amount of microorganisms (bacteria, fungus and actinomycets) and the inorganic nitrogen content (NO3 - and NH4 + ). The sites of study were classified in function of cat claw densities and the cover of grasses, the site A with less cat claw density (50 plants / ha) and high grass density (80%), the site B with medium cat claw density (250 to 500 plants / ha) and 30 to 70% of grasses coverage, and the site C with the higher cat claw density (500 plants / ha) and with the less grass coverage (less than 30%). Were found more carbon inside the canopy than outside, that increase was higher in higher cat claws densities (site C). The increase of the amount of bacteria was proportional to cat claw density. The abundance of fungus shows an inverse behavior than bacteria because the higher abundance was found in the site with less cat claw density. The higher abundance of actinomycets was found in the site that was considered with medium density (site B). The inorganic nitrogen content was higher inside the canopy than outside. The ammonium content was lower than the nitrates content; this shows the possible occurrence of nitrification processes in those soils.