INVESTIGADORES
ROSTAGNO Cesar Mario
artículos
Título:
Grazing Impacts in Vegetated Dune Fields: Predictions From Spatial Pattern Análisis
Autor/es:
BLANCO, P. D., C. M. ROSTAGNO, H. F. DEL VALLE, A. M. BEESKOW, AND THORSTEN WIEGAND.
Revista:
Rangeland Ecology and Management (ex JRM)
Editorial:
SOC RANGE MANAGEMENT
Referencias:
Año: 2008 vol. 61 p. 194 - 203
ISSN:
1550-7424
Resumen:
This study deals with the changes induced by grazing on soil erosion processes in vegetated dune fields of Pený´nsula Valde´s, in the
Patagonia region of Argentina. We performed a spatial analysis to assess erosion features patterns. Blowouts, used as main
indicators of aeolian erosion processes, as well as dune crests, which are susceptible to erosion, were mapped on aerial photographs
and images from Landsat 7 Enhanced Thematic Mapper Plus, in eight paddocks under two grazing conditions: lightly (0.4
sheep ? ha21) and heavily grazed (0.8 sheep ? ha21). From the mapped locations of water points, crests, and blowouts we
calculated a spatial statistic (O-ring statistic), which gives the expected intensity of blowouts within the area covered by crests as
function of distance away from water points. Additionally, to explore if the density of crests around water points influences the
density of blowouts, we estimated the intensity of dune crests in the neighborhood of water points and compared the densities of
blowouts among water points with low, medium, and high densities of crests. For the heavy grazing treatment we found highly
significant (P,0.05) aggregation of blowouts around water points with peak densities threefold higher than expected at random
occurring between 90 and 210 m. However, the aggregation was only weakly significant for the light grazing treatment and
occurred only at distances of about 30 m away from the water point. We found that the impact of grazing on soil stability
contrasted among sites with different sensitivity to accelerated erosion. In sites with a high density of dune crests close to water
points, wind erosion becomes more intense and the density of blowouts increases. A more sustainable management of these
rangelands depends primarily on the conservation of the soils. Therefore, the location of water points in sites not susceptible to
accelerated soil erosion would represent a better management strategy of the dune fields of Pený´nsula Valde´s.? ha21) and heavily grazed (0.8 sheep ? ha21). From the mapped locations of water points, crests, and blowouts we
calculated a spatial statistic (O-ring statistic), which gives the expected intensity of blowouts within the area covered by crests as
function of distance away from water points. Additionally, to explore if the density of crests around water points influences the
density of blowouts, we estimated the intensity of dune crests in the neighborhood of water points and compared the densities of
blowouts among water points with low, medium, and high densities of crests. For the heavy grazing treatment we found highly
significant (P,0.05) aggregation of blowouts around water points with peak densities threefold higher than expected at random
occurring between 90 and 210 m. However, the aggregation was only weakly significant for the light grazing treatment and
occurred only at distances of about 30 m away from the water point. We found that the impact of grazing on soil stability
contrasted among sites with different sensitivity to accelerated erosion. In sites with a high density of dune crests close to water
points, wind erosion becomes more intense and the density of blowouts increases. A more sustainable management of these
rangelands depends primarily on the conservation of the soils. Therefore, the location of water points in sites not susceptible to
accelerated soil erosion would represent a better management strategy of the dune fields of Pený´nsula Valde´s.O-ring statistic), which gives the expected intensity of blowouts within the area covered by crests as
function of distance away from water points. Additionally, to explore if the density of crests around water points influences the
density of blowouts, we estimated the intensity of dune crests in the neighborhood of water points and compared the densities of
blowouts among water points with low, medium, and high densities of crests. For the heavy grazing treatment we found highly
significant (P,0.05) aggregation of blowouts around water points with peak densities threefold higher than expected at random
occurring between 90 and 210 m. However, the aggregation was only weakly significant for the light grazing treatment and
occurred only at distances of about 30 m away from the water point. We found that the impact of grazing on soil stability
contrasted among sites with different sensitivity to accelerated erosion. In sites with a high density of dune crests close to water
points, wind erosion becomes more intense and the density of blowouts increases. A more sustainable management of these
rangelands depends primarily on the conservation of the soils. Therefore, the location of water points in sites not susceptible to
accelerated soil erosion would represent a better management strategy of the dune fields of Pený´nsula Valde´s.P,0.05) aggregation of blowouts around water points with peak densities threefold higher than expected at random
occurring between 90 and 210 m. However, the aggregation was only weakly significant for the light grazing treatment and
occurred only at distances of about 30 m away from the water point. We found that the impact of grazing on soil stability
contrasted among sites with different sensitivity to accelerated erosion. In sites with a high density of dune crests close to water
points, wind erosion becomes more intense and the density of blowouts increases. A more sustainable management of these
rangelands depends primarily on the conservation of the soils. Therefore, the location of water points in sites not susceptible to
accelerated soil erosion would represent a better management strategy of the dune fields of Pený´nsula Valde´s.