OLIVERA nelda Lila
congresos y reuniones científicas
Spatial pattern of soil dehydrogenase activity in arid rangelands of the Patagonian Monte
NELDA LILA OLIVERA; ANALÍA CARRERA; MARISA GARCÉS; MÓNICA BERTILLER
Mar del Plata
Congreso; VIII Congreso SAMIGE 2012; 2012
The activity of soil microorganisms involved in organic matter decomposition and nutrient cycling may be assessed by the activity of dehydrogenase enzymes which catalyze soil organic matter oxidation. We studied the spatial pattern of soil dehydrogenase activity (SDA) in patches of litter and its relationship with vegetation and soil properties in two typical Patagonian Monte paddocks (with a stocking rate of 0.14 sheep/ha since the early 1900s): one with domestic herbivores at present (G) and the other without domestic herbivores since 2006 (NG). At each paddock, we randomly selected 105 modal size plant-covered patches and identified microsites with maximal litter cover associated with each patch and the respective neighbouring inter-canopy area. At each litter patch, we measured the resistance of soil penetration and extracted one upper soil core to quantify the SDA, the pebble volume and the litter mass. At both G and NG, the patches with maximal litter accumulation were associated with plant-covered patches and had lower pebble content and soil penetration resistance than inter-canopy areas. At plant-covered patches, SDA was higher at G than at NG (14.63 ± 4.57 vs. 11.41 ± 3.55 µg triphenyl formazan (TPF)/g dry soil h, respectively). At inter-canopy areas, SDA decreased and there was no significant difference between G and NG (10.11 ± 3.66 vs. 10.12 ± 3.99 µg TPF/g dry soil h, respectively). SDA was positively correlated to soil penetration, and litter cover and mass. Results showed a heterogeneous spatial pattern of SDA in both paddocks independently of domestic grazing exclusion, and indicated that SDA may diminish in degraded or denuded areas with high soil compaction and low litter accumulation.