Spatial patterns of soil moisture and nitrate as a function of distance from the livestock corrals in the monte desert

MEGLIOLI, P.A.; VILLAGRA, P.E.; ARANIBAR, J.N.

Congreso; XXX Reunión Anual de la Sociedad de Biología de Cuyo; 2012

Sociedad de biología de Cuyo

In the Monte desert, livestock settlements generate environmental grazing gradients and represent an opportunity to study the effects of grazing pressures on spatial patterns of nutrients and water. In such context, we expected these spatial patterns be modified, both horizontally and vertically, as a function of distance from livestock corrals. We analyzed nitrate and water contents and salinity (electrical conductivity) on six linear transects (65 to 75 m along) corresponding to three livestock stations (LS) and three undisturbed control woodlands (CW). On each transect, we sampled soil profiles (up to 200 cm depth) every 5 m. In the initial, middle and final points of each transect, we collected soil samples from up to 400 cm depth. Transects in the LS began in a corral, whereas those in the CW began at the bottom of the valley. Nitrate and water contents in all depth intervals were greater at the LS than at the CW. Horizontal distribution patterns in LS showed a negative relation of water, nitrate, and conductivity with distance from the corrals. CW did not show a relation of these variables with distance from the valley bottom. This pattern was evident for surface soils. Conductivity was lower in the LS, although the topsoil of corrals had the highest values compared to the CW soils. Our results demonstrate that LS produce biogeochemical soil changes, causing a centripetal pattern of nitrate, water, and salt accumulation in the vicinity of the corrals.