Soil Physical Changes After Conversion of Woodlands to Pastures in Dry Chaco Rangelands (Argentina)

Magliano, Patricio N.; Fernández, Roberto; Florio, Eva L.; Murray, Francisco; Jobbágy, Estéban G.

doi:10.1016/j.rama.2016.08.003

Cited by 25 publications

(26 citation statements)

References 56 publications

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“…Soil diversity and its physical, chemical, biological, mineralogical, and morphological attributes, as well as its relief, stony characteristic, and climate, cause soils to respond differently to management, machine traffic, and animal trampling (Magliano, Fernández, Florio, Murray, & Jobbágy, 2017).…”

Section: Introductionmentioning

confidence: 99%

Spatial variability of soil physical-hydric attributes under bovine trampling in agreste of Pernambuco State, Brazil

et al. 2018

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Soils under pastures suffer physical modifications, in greater or lesser intensity, via the action of animal trampling. Thus, the aim was to evaluate the spatial dependence of soil physical attributes under bovine trampling. The trial was performed at Roçadinho Farm, Agreste of Pernambuco, Brazil, in a 40 x 40 m paddock that was managed with continuous stocking by bovines and 12 AU ha-1 stocking rate. Soil samples were collected before and after grazing using a 6 x 6 m grid, totaling 36 sampling points. At each point, the bulk density, total porosity, moisture, soil penetration resistance at 0.00-0.10, 0.10-0.20, and 0.20-0.30 m depth were estimated, as was the hydraulic conductivity on the saturated soil surface. Descriptive statistics and geostatistics supported the data analysis. A normal distribution was verified for all variables, which were scored as either low or high variability in terms of the variation coefficient. The physical attributes (density, total porosity, moisture, soil penetration resistance and hydraulic conductivity) of the soil sampled presented a strong spatial dependence before and after grazing.

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Section: Introductionmentioning

confidence: 99%

Spatial variability of soil physical-hydric attributes under bovine trampling in agreste of Pernambuco State, Brazil

et al. 2018

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“…This water concentration can overcome the higher interception losses of densely vegetated patches respect to sparsely vegetated ones (Ludwig et al, 2005;Nouwakpo et al, 2016). In addition, vegetated patches often present lower water holding capacity, which facilitates the water storage deeper in the soil profile (Caldwell et al, 2012;Lebron et al, 2007;Magliano et al, 2017). In a possible climate-change scenario, characterized by less frequent but larger and more intense rainfall events (IPCC, 2014;Trenberth, Dai, Rasmussen, & Parsons, 2003), water concentration in densely vegetated patches would be enhanced, generating a positive feedback on plant transpiration and carbon uptake.…”

Section: Resultsmentioning

confidence: 99%

“…So, n = 54 in forests (18 patches × 3 transects) and n = 27 in pastures (9 patches × 3 transects). More observations were considered necessary in forest than in pasture because of the higher heterogeneity of the former in our study site (Magliano et al, 2016;Magliano et al, 2017;Marchesini, Fernández, & Jobbágy, 2013;Marchesini, Fernández, Reynolds, Sobrino, & Di Bella, 2015).…”

Section: Methodsmentioning

confidence: 99%

“…Basically, the daily water balance of a surface soil layer with the characteristics of the micro-lysimeters (18 cm depth, 28 mm of water retention at field capacity) was simulated. In addition, vegetated patches often present lower water holding capacity, which facilitates the water storage deeper in the soil profile (Caldwell et al, 2012;Lebron et al, 2007;Magliano et al, 2017). Evaporation losses were computed as the product of daily ET 0 and the corresponding K E for each of these patches respect to a no-redistribution situation (Caldwell, Young, Zhu, & McDonald, 2008;Wilcox et al, 2003).…”

Section: Figurementioning

confidence: 99%

“…Vegetation influences evaporation in at least four different ways: (a) by surface run-off/ run-on redistribution processes that concentrate water in densely vegetated patches (Magliano, Breshears, Fernández, & Jobbágy, 2015;Urgeghe, Breshears, Martens, & Beeson, 2010;Wilcox et al, 2003), (b) by altering soil physics, for example, changing its hydraulic conductivity and/or its water holding capacity (Caldwell, Young, McDonald, & Zhu, 2012;Lebron et al, 2007;Magliano, Fernández, Florio, Murray, & Jobbágy, 2017), (c) by plant water uptake (transpiration), which decreases soil moisture (Newman et al, 2006;Rodriguez-Iturbe, 2000), and (d) by altering micro-meteorological conditions at the soil surface, thus reducing atmospheric demand (Haverd & Cuntz, 2010;Ritchie & Burnett, 1971). In the last two decades, much effort has been devoted to understand vegetation micro-meteorological effects on evaporation losses because they are highly sensitive to human transformations (Ferretti et al, 2003;Haverd & Cuntz, 2010;Köstner, 2001), such as wood plant encroachment caused by livestock intensification (Huxman et al, 2005;Wilcox & Huang, 2010), or agricultural practices on recently cleared lands (Ji & Unger, 2001;Van Donk et al, 2010).…”

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Litter is more effective than forest canopy reducing soil evaporation in Dry Chaco rangelands

et al. 2017

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Soil evaporation is a dominant water flux of flat dry ecosystems, reducing available water for plant transpiration. Vegetation plays a key role at controlling evaporation, especially by altering soil surface micro‐meteorological conditions. Here, we explored the vegetation cover effect on soil evaporation, differentiating the effects of canopy cover (shadow) and of surface cover (litter) in forests and pastures of Dry Chaco rangelands (San Luis, Argentina). We measured daily soil evaporation using irrigated micro‐lysimeters installed at regularly spaced (2 m) patches along transects in native dry forests (n = 54 patches) and pastures (n = 27 patches). In each forest patch, we established a pair of micro‐lysimeters, one with litter (3 cm depth, representing high litter cover conditions of the site) and one with bare soil, but in pastures, only one micro‐lysimeter with bare soil was installed at each patch (representing the typical no litter cover conditions of pastures of the study site). We found that, when soil water was not limiting, litter cover had the strongest effect in reducing evaporation rates, with a 4‐ and 6.4‐fold reduction respect to bare soil micro‐lysimeters in the forest and pasture, respectively. Evaporation decreased sharply with declining incident radiation fraction in bare soil micro‐lysimeters from 5.6 mm/day (full radiation) to 3.5 mm/day (full canopy shadow; R2 = 0.50). Litter‐covered micro‐lysimeters showed lower and more stable evaporation rates, decreasing only from 1.35 to 1.03 mm/day under the same radiation conditions (R2 = 0.10). In accordance with J.T. Ritchie evaporation model, we identified a threshold of ~10.5 mm of cumulative evaporation at which evaporation switched from energy to water limitation in all situations, as revealed by declining evaporation rates and raising surface temperatures. Under typical wet–summer conditions, the pasture, the forest with bare soil, and the forest with litter would need on average a drying cycle of 1.5, 2.5, and 9.5 days, respectively, to reach that threshold. Simulations showed that, considering the distribution of rainfall events at our study site, litter would maintain evaporation in the energy‐limited mode most of the time (68.8% of summer days), potentially favouring transpiration. The ecohydrological key role of soil litter controlling evaporation highlights the importance of an accurate assessment of management practices controlling the evaporation/transpiration partition in dry ecosystems.

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South American Dry Chaco rangelands: Positive effects of cattle trampling and transit on ecohydrological functioning

Magliano

Breshears

Murray

et al. 2023

Ecological Applications

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Livestock production in drylands requires consideration of the ecological applications of ecohydrological redistribution of water. Intensive cattle trampling and the associated increase of surface runoff are common concerns for rangeland productivity and sustainability. Here, we highlight a regional livestock production system in which cattle trails and trampling surrounding an artificial impoundment are purposely managed to enhance redistribution and availability of water for cattle drinking. Based on literature synthesis and field measurements, we first describe cattle production systems and surface water redistribution in the Dry Chaco rangelands of South America, and then develop a conceptual framework to synthesize the ecohydrological impacts of livestock production on these ecosystems. Critical to this framework is the pioshere-a degraded overgrazed and overtrampled area where vegetation has difficulties growing, usually close to the water points. The Dry Chaco rangelands have three key distinctive characteristics associated with the flat sedimentary environment lacking fresh groundwater and the very extensive ranching conditions: (1) cattle drinking water is provided by artificial impoundments filled by runoff, (2) heavy trampling around the impoundment and its adjacent areas generates a piosphere that favors runoff toward the impoundment, and (3) the impoundment, piosphere, and extensive forage areas are hydrologically connected with a network of cattle trails. We propose an ecohydrological framework where cattle transit and trampling alter the natural water circulation of these ecosystems, affecting small fractions of the landscape through increased runoff (compaction in piosphere and trails), surface connectivity (convergence of trails to piosphere to impoundment), and ponding (compaction of the impoundment floor) that operate together making water harvesting and storage possible. These effects have likely generated a positive water feedback on the expansion of livestock in the region with a relatively low impact on forage production. We highlight the role of livestock transit as a geomorphological agent capable of reshaping the hydrology of flat sedimentary rangelands in ways that can be managed positively for sustainable ranching systems. We suggest that the Dry Chaco offers an alternative

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Soil Physical Changes After Conversion of Woodlands to Pastures in Dry Chaco Rangelands (Argentina)

Cited by 25 publications

References 56 publications

Spatial variability of soil physical-hydric attributes under bovine trampling in agreste of Pernambuco State, Brazil

Spatial variability of soil physical-hydric attributes under bovine trampling in agreste of Pernambuco State, Brazil

Litter is more effective than forest canopy reducing soil evaporation in Dry Chaco rangelands

South American Dry Chaco rangelands: Positive effects of cattle trampling and transit on ecohydrological functioning

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