Mounds associated with shrubs in aridic soils of northeastern Patagonia: Characteristics and probable genesis

Rostagno, César Mario; Valle, Héctor F. del

doi:10.1016/0341-8162(88)90056-2

Cited by 97 publications

(68 citation statements)

References 8 publications

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“…Although in areas of NE Patagonia some studies have lately recognized the incidence of soil erosion as an important process on permanent vegetation changes (Rostagno and del Valle 1988;Parizek et al 2002) and others have analyzed the vegetation dynamics in the context of state-and-transition models (see Laycock 1995;Bertiller and Bisigato 1998) functional or structural thresholds associated with a decrease in plant cover have not been analyzed. Grazing rates to prevent accelerated erosion are certainly unknown.…”

Section: Introductionmentioning

confidence: 99%

Soil Erosion Thresholds and Alternative States in Northeastern Patagonian Rangelands

Chartier¹,

Rostagno²

2006

REM

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In semiarid rangelands, continuous grazing may decrease vegetation cover, accelerating soil erosion and eventually causing a transition to an alternative, degraded state. State-and-transition models invoke process-based explanations of alternative states, but there are few examples that use empirical data on key factors and processes. We used rainfall simulation to determine 1) the relationships between soil surface characteristics and interrill erosion in 3 spatially related plant communities: stable grass with scattered shrubs (GS), degraded grass with scattered shrubs (DGS), and degraded shrub steppes (DSS), and 2) the site conservation threshold (SCT) of this rangeland. We also analyzed the effect of past erosion on soil and vegetation characteristics. In the GS, sediment production and sediment concentration were significantly lower (p , 0.05) than in the DGS and the DSS. The main soil protection factors in the GS and in the DGS were perennial grass and litter cover, while in the DSS, gravel cover became the main soil protection factor. The SCT, the point at which the rate of soil erosion increases markedly, corresponded to a plant-and-litter cover close to 90% and occurred within the DGS. Although this plant community may reverse back to the conserved GS, long-term accelerated erosion may result in enough soil loss to trigger irreversible changes and prompt the transition to the DSS. The threshold underlying this transition would be reached when the A horizon is severely reduced by erosion. Under these conditions, the soil hydrological properties are affected irreversibly, preventing perennial grass establishment. While the GS represents a resource conserving plant community, desirable for both forage production and soil protection, the DSS represents a dysfunctional state with a minimum forage value. The DGS represents an unstable and transitional community that, without management intervention to halt soil erosion, will likely change into the DSS. ResumenEn los pastizales naturales semiá ridos, el pastoreo continuo puede disminuir significativamente la cobertura de la vegetació n, acelerar la erosió n del suelo y eventualmente causar una transició n hacia estados alternativos degradados. Los modelos de estados y transiciones generalmente explican estados alternativos en funció n de distintos procesos, sin embargo hay pocos ejemplos que usen datos empíricos. Nosotros empleamos lluvia simulada a los fines de determinar 1) las relaciones entre las características superficiales del suelo y la vegetació n y la erosió n laminar en 3 comunidades vegetales espacialmente relacionadas: una estepa herbá cea con arbustos (EH), una estepa herbácea degradada con arbustos (EHD), y una estepa arbustiva degradada (EAD), y 2) el umbral de conservació n del sitio (UCS) en éste pastizal. También analizamos el efecto de la erosió n histó rica sobre las características superficiales del suelo y la vegetació n. En la EH la producció n y la concentració n de sedimentos fueron significativamente má s bajos (p , 0.05) que...

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Section: Introductionmentioning

confidence: 99%

Soil Erosion Thresholds and Alternative States in Northeastern Patagonian Rangelands

Chartier¹,

Rostagno²

2006

REM

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“…These relations were attributed primarily to the presence of shrubs in the combined plots: runoff and sediments that developed in the "bare" soil reached the shrubs, where a great part of them were trapped by the shrub and settled in situ, while the remaining (minor) part continued to flow. This ability of the shrubs to collect runoff resulted from the combined effects of several processes that enhance infiltration: the shrub canopy and the litter beneath it soften direct raindrop impact on the soil and dissipate their kinetic energy, thereby preventing formation of mechanical crusts and, in turn, enhancing infiltration (Rostango and del Valle, 1988;Dunkerley and Brown, 1995;Bromley et al, 1997). Moreover, shrubs act as a physical barrier that moderates overland flow velocity and continuity (Sanchez and Puigdefabregas, 1994); consequently, they trap soil and litter (Bergkamp, 1998;Shachak et al, 1998), forming soil mounds (Rostango and del Valle., 1988;Parsons et al, 1992) and thereby changing the surface microtopography as well as the soil texture and bulk density (Van Haveren, 1983;Trimble and Mendel 1995;Stavi et al, 2008bStavi et al, , 2009).…”

Section: Patch Functionsmentioning

confidence: 99%

“…This ability of the shrubs to collect runoff resulted from the combined effects of several processes that enhance infiltration: the shrub canopy and the litter beneath it soften direct raindrop impact on the soil and dissipate their kinetic energy, thereby preventing formation of mechanical crusts and, in turn, enhancing infiltration (Rostango and del Valle, 1988;Dunkerley and Brown, 1995;Bromley et al, 1997). Moreover, shrubs act as a physical barrier that moderates overland flow velocity and continuity (Sanchez and Puigdefabregas, 1994); consequently, they trap soil and litter (Bergkamp, 1998;Shachak et al, 1998), forming soil mounds (Rostango and del Valle., 1988;Parsons et al, 1992) and thereby changing the surface microtopography as well as the soil texture and bulk density (Van Haveren, 1983;Trimble and Mendel 1995;Stavi et al, 2008bStavi et al, , 2009). The combined physical, chemical and biological effects of shrub roots (Archer et al, 2002) and soil biological activity (Garner and Steinberger, 1989) improve soil organic matter content and structure (Oades, 1984;Sarah and Rodeh, 2004;Sarah, 2006), which reduces bulk density even more (Dunkerley and Brown, 1995), and creates macropores, in which water flows vertically at relative high rates (Bromley et al, 1997).…”

Section: Patch Functionsmentioning

confidence: 99%

Livestock redistribute runoff and sediments in semi-arid rangeland areas

Sarah

Zonana

2015

Solid Earth

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Abstract. Semi-arid areas where grazing is the main land use exhibit a "three-phase-mosaic" pattern of dominant surface patches: shrubs, trampling routes, and intershrub areas. This pattern differs from the "two-phase mosaic" seen in grazing-free semi-arid areas. The patches might create a positive feedback process in which enhanced infiltration beneath shrubs minimizes overland flow from under their canopies, thereby strengthening the sink-source mechanism by which overland flow generated between shrubs rapidly infiltrates into the soil beneath them, where it deposits soil particles, litter, nutrients and organic matter, thereby enhancing infiltration by changing the local microtopography, and improving soil properties. To analyze sink-source relationships among the patches in grazed areas in rangelands of the semi-arid northern Negev region of Israel, we constructed small runoff plots, 0.25-1.0 m 2 in area, of five types: shrub (Sarcopoterium spinosum), intershrub, route, route-shrub combination, and intershrub-shrub combination. The shrubs always occupied the downslope part of the plot. Overland flow and sediment deposits were measured in all plots during 2007/8 and 2008/9. The combined plots yielded much less overland flow and sediments than intershrub, routes and shrub ones, indicating that the shrubs absorbed almost all the yields of the upper part of their plots. The shrubs generated less runoff and sediments than routes and intershrubs; runoff flows from the routes and intershrubs were similar; sediment yield was highest in the intershrubs. Thus, runoff yield exhibited a twophase mosaic pattern, and sediment yield, i.e., soil erosion, a three-phase mosaic pattern.

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“…Tales estudios se han realizado tanto en ambientes semiáridos (ROSTAGNO and DEL VALLE, 1988;SÁNCHEZ and PUIGDEFÁBREGAS, 1994), como en alpinos (GALLART et al, 1993). En las áreas semiáridas, se han de reseñar los estudios de islas de fertilidad, áreas vegetadas que en cierta manera aprovechan el Mediterránea Serie de estudios biológicos (2000) agua y los sedimentos que les aportan las zonas desnudas.…”

Section: Cómo Afecta La Erosión a La Vegetaciónunclassified

Efectos de la erosión del suelo sobre los patrones de la vegetación y su composición florística: una revisión bibliográfica

Campo¹

2005

MDTRRA

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Mounds associated with shrubs in aridic soils of northeastern Patagonia: Characteristics and probable genesis

Cited by 97 publications

References 8 publications

Soil Erosion Thresholds and Alternative States in Northeastern Patagonian Rangelands

Soil Erosion Thresholds and Alternative States in Northeastern Patagonian Rangelands

Livestock redistribute runoff and sediments in semi-arid rangeland areas

Efectos de la erosión del suelo sobre los patrones de la vegetación y su composición florística: una revisión bibliográfica

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