Soil microbial structure and activity in a semiarid rangeland of Patagonia, Argentina: Plant species and defoliation effects

Natural grasslands are an important renewable resource for livestock production. Grazing in these areas alters the plant community composition, litter quality, and soil microbial structure activity. Three cool-season species were studied a semiarid rangeland area of Argentina: Poa ligularis Nassella tenuis (desirable/preferred livestock) Amelichloa ambigua (undesirable/non preferred). The objective was to analyze effect moderate defoliation on activity communities associated with their roots. In winter 2012, samples (0–10 cm) taken underneath marked canopies three (n = 8). Immediately thereafter, half plants 4) defoliated (5 cm stubble height) other remained undefoliated (controls). treatment conducted again spring. Soil 30 days after each event. study repeated 2013, using different set. Bacterial analyzed PCR-DGGE analysis basal respiration, respectively. Moderate early defoliations allowed compensatory growth plants. Variations genetic profiles A. suggest higher dependence its rhizospheric bacterial communities. Defoliation treatments did not substantially affect respiration but showed strong links between desirable Sustainable management practices that promote persistence development respond quickly stress conditions, favoring decomposition processes maintain fertility grasslands. • affected ambigua. respiration. soils modulating