Spatial patterns of soil resources under different land use in Prosopis woodlands of the Monte desert

PABLO MEGLIOLI; JULIETA N. ARANIBAR; PABLO E. VILLAGRA; CECILIA VEGA RIVEROS

CATENA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016

0341-8162

Changes in the spatial distribution of resourcesconstitute an indicator of degradation of arid grazing lands. In aridand semi-arid ecosystems, the distribution of soil resources has beencommonly associated with the structure and the spatial arrangementsof the vegetation. Although the formation of ?fertile islands?beneath vegetation patches is well documented, much less is knownabout the changes induced by grazing systems on the distribution ofsoil resources. We examine how pastoralist settlements affect thespatial distribution of soil resources and the soil nutrient balancein central-western woodlands of Argentina. We analyzed thedistribution of soil water, chloride, nitrate, total nitrogen, andorganic matter at increasing distances from livestock corrals and inundisturbed woodlands, at different soil depths. We also calculatedvariation indexes of soil organic matter and total nitrogen producedby livestock settlements, as an indicator of degree of deteriorationor improvement of the soils. The transects located in pastoralistsettlements demonstrated an increasing centripetal gradient inavailability of soil water and nutrients compared to transectsoutside of these disturbed areas. Livestock corrals create localhotspots of nutrient enrichment, but when we analyzed the effects oflivestock settlement at a higher spatial scale, we found net lossesof soil organic matter and total nitrogen. We conclude that thecoupling between nutrient and patch dynamics is disrupted by thepastoralist settlements, which caused a redistribution of soilresources, controlled by the location from the livestock corrals. Theprocesses that promote nutrient losses, such as ammoniumvolatilization, denitrification, nitrate leaching, organic matteroxidation, manure exports, and soil erosion, are relatively higherthan the extra inputs of dung and urine. Therefore, this studyemphasizes the role of grazing systems as a modulator of water andnutrient fluxes, and soil nutrient balance.