Soil microtopography on grazing gradients in Chihuahuan desert grasslands

Nash, Maliha S.; Jackson, Erik; Whitford, Walter G.

doi:10.1016/s0140-1963(02)00251-3

Cited by 33 publications

(27 citation statements)

References 18 publications

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“…This resulted in a collapse of the spatially patterned system that was seen in both years of observation. Although the general predictions are consistent with observational studies on the effects of increased grazing on patch formation in arid grasslands (Rietkerk et al 2000, Nash et al 2003, Stavi et al 2009), experimental evidence for the effects of grazing on the formation of spatial vegetation patterns, and on the interaction between plants and abiotic processes, is limited. Our experimental results confirm the hypothesis that grazing affects the functioning (e.g., sediment accretion and diatom biomass) of self-organized landscapes by interfering with feedbacks between organisms and sedimentary process- es.…”

Section: Discussionsupporting

confidence: 75%

Top-down control inhibits spatial self-organization of a patterned landscape

Weerman

Herman

Koppel

2011

Ecology

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Abstract. Regular, self-organized spatial patterns in primary producers have been described in a wide range of ecosystems and are predicted to affect community production and resilience. Although consumers are abundant in most systems, the effect of trophic interactions on pattern formation in primary producers remains unstudied. We studied the effects of top-down control by herbivores on a self-organized landscape of regularly spaced, diatom-covered hummocks alternating with water-filled hollows on an intertidal mudflat in The Netherlands. Spatial patterns developed during spring but were followed by a rapid collapse in summer, leading to a flat landscape with low diatom densities and little variation in sediment bed level. This dramatic decline co-occurred with a gradual increase of benthic herbivores. A manipulative field experiment, where benthic herbivores were removed from the sediment, revealed that both diatom growth and hummock formation were inhibited by the activity of benthic herbivores. Our study provides clear evidence of top-down control of spatial selforganized patterns by benthic herbivores within a biological-geomorphic landscape.

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Section: Discussionsupporting

confidence: 75%

Top-down control inhibits spatial self-organization of a patterned landscape

Weerman

Herman

Koppel

2011

Ecology

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“…(e.g., Belnap and Gillette, 1997;Gillette et al, 1980;Nash et al, 2003). Although Tegen et al (2004) suggest that agricultural land use is responsible for less than 10% of global dust loads, recent studies demonstrate large increases in dust flux due to historic land use on a regional scale (Lee et al, 1993;Neff et al, 2008;Reynolds et al, 2009b).…”

Section: Effects Of Dust Source and Land Usementioning

confidence: 99%

Regional and climatic controls on seasonal dust deposition in the southwestern U.S.

Reheis

Urban

2011

Aeolian Research

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a b s t r a c tVertical dust deposition rates (dust flux) are a complex response to the interaction of seasonal precipitation, wind, changes in plant cover and land use, dust source type, and local vs. distant dust emission in the southwestern U.S. Seasonal dust flux in the Mojave-southern Great Basin (MSGB) deserts, measured from 1999 to 2008, is similar in summer-fall and winter-spring, and antecedent precipitation tends to suppress dust flux in winter-spring. In contrast, dust flux in the eastern Colorado Plateau (ECP) region is much larger in summer-fall than in winter-spring, and twice as large as in the MSGB. ECP dust is related to wind speed, and in the winter-spring to antecedent moisture. Higher summer dust flux in the ECP is likely due to gustier winds and runoff during monsoonal storms when temperature is also higher. Source types in the MSGB and land use in the ECP have important effects on seasonal dust flux. In the MSGB, wet playas produce salt-rich dust during wetter seasons, whereas antecedent and current moisture suppress dust emission from alluvial and dry-playa sources during winter-spring. In the ECP under drought conditions, dust flux at a grazed-and-plowed site increased greatly, and also increased at three annualized, previously grazed sites. Dust fluxes remained relatively consistent at ungrazed and currently grazed sites that have maintained perennial vegetation cover. Under predicted scenarios of future climate change, these results suggest that an increase in summer storms may increase dust flux in both areas, but resultant effects will depend on source type, land use, and vegetation cover.Published by Elsevier B.V.

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“…Overgrazing occurs when herbivore density is well above carrying capacity but can also occur with low herbivore densities if the spatial pattern of foraging is highly uneven (Coughenour 1991, Pringle and Landsberg 2004). Uneven (Nasha et al 2003). A more even distribution of animals tends to minimize undesirable effects of overgrazing by dispersing impacts across a larger part of the landscape.…”

Section: Ecological Consequences Of the Observed Foraging Patternsmentioning

confidence: 99%

Foraging behavior of heritage versus recently introduced herbivores on desert landscapes of the American Southwest

et al. 2011

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Abstract. Since the 1800s managed grasslands and shrublands of the arid American Southwest have been grazed predominantly by cattle originally bred for temperate climates in northern Europe. A heritage breed, the criollo cattle, has survived in northern Mexico for more than 400 years under desert-like conditions of low and variable rainfall, hot temperatures in the growing season, and both spatially and temporally scarce levels of primary production. We tested the hypothesis that the heritage breed has a broader spatial foraging distribution under harsh environmental conditions, and that its distribution is driven by environmental variables which differ from those that control the distribution of the introduced European breed. Movements of individual criollo and Angus breed animals were monitored autonomously in the northern Chihuahuan desert of southern New Mexico, USA. Georeferenced foraging locations acquired at 5-minute intervals for each animal were fit to a logistic regression using environmental factors as predictors. In the spring, when forage availability was high and more uniformly distributed across the landscape, animal foraging patterns were similar for both breeds. In the fall when forage availability was low and non-uniformly distributed, the two breeds exhibited very different foraging patterns: heritage animals foraged across a much larger spatial extent whereas their domestic counterparts remained in close proximity to the permanent source of water. These differences in foraging behavior driven by environmental variables have important implications for sustainability of rangelands in spatially and temporally variable environments. Heritage breeds of animals that are generalist foragers during unfavorable conditions can reduce environmental impacts compared to more recently introduced breeds.Key words: Chihuahuan desert; criollo cattle; GPS monitoring; herbivory; landscape foraging patterns; resource selection functions. Ecosphere 2(5):art57.

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Soil microtopography on grazing gradients in Chihuahuan desert grasslands

Cited by 33 publications

References 18 publications

Top-down control inhibits spatial self-organization of a patterned landscape

Top-down control inhibits spatial self-organization of a patterned landscape

Regional and climatic controls on seasonal dust deposition in the southwestern U.S.

Foraging behavior of heritage versus recently introduced herbivores on desert landscapes of the American Southwest

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