Biodiversity of Rangelands

West, Neil E.

doi:10.2307/4002440

Cited by 169 publications

(106 citation statements)

References 73 publications

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“…The effect of grazing on biodiversity may differ widely, ranging from positive (Noy-Meir 1995) or unimodal responses (Milchunas et al 2008) to negative effects (West 1993, Zhang et al 2005. Effects of grazing are often positive where the rangeland vegetation has coevolved with grazing and is adapted to it (Milchunas and Lauenroth 1993).…”

Section: Discussionmentioning

confidence: 99%

“…We are acutely aware that the term ''degradation'' is emotionally charged and can be highly subjective. Definitions vary among authors, and can range from loss in species diversity (West 1993) to the reduction of productivity (Wessels et al 2007) or irreversible changes in soils (Illius and O'Connor 1999). We also cannot rule out a certain level of ''observer bias,'' that is, given the subjective nature of degradation, some authors may be more likely to find evidence of degradation than others.…”

Section: Database Of Case Studiesmentioning

confidence: 99%

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Global assessment of the non‐equilibrium concept in rangelands

Wehrden

Hanspach

Kaczensky

et al. 2012

Ecological Applications

132

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Abstract. The non-equilibrium concept of rangeland dynamics predicts that the potential for grazing-induced degradation is low in rangelands with relatively variable precipitation. To date, evidence in support of the non-equilibrium concept has been inconsistent. Using a standardized protocol, including a newly developed global map of rainfall variability, we reviewed the incidence of degradation in relation to rainfall variability across 58 published studies. We distinguished between (1) zonal degradation (i.e., degradation independent of water and key resources), (2) degradation in the presence of key resources, and (3) degradation in the presence of water. For studies not affected by proximity to permanent water or key resources, we found strong support for the non-equilibrium concept for rangelands. Zonal degradation was absent at CV (coefficient of variation) values above 33%, which has been proposed as a critical threshold. Grazing degradation was almost entirely restricted to areas with relatively stable annual precipitation as expressed by a low CV, or to rangelands with key resources or water points nearby. To better understand rangeland dynamics, we recommend that future studies use globally comparable measures of degradation and rainfall variability. Our work underlines that rangelands with relatively stable rainfall patterns, and those with access to water or key resources, are potentially vulnerable to degradation. Grazing management in such areas should incorporate strategic rest periods. Such rest periods effectively mimic natural fluctuations in herbivore populations, which are a defining characteristic of non-degraded rangelands occurring under highly variable precipitation regimes.

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Section: Discussionmentioning

confidence: 99%

Section: Database Of Case Studiesmentioning

confidence: 99%

Global assessment of the non‐equilibrium concept in rangelands

Wehrden

Hanspach

Kaczensky

et al. 2012

Ecological Applications

132

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“…El conocimiento y conservación de la biodiversidad y de los procesos ecológicos que sustentan la sabana son de gran interés en el manejo de ecosistemas (He y Legendre, 2002;Tilman y Downing, 1996;West, 1993), por lo que se busca entender las relaciones entre la diversidad de especies y el pastoreo (Milchunas et al, 1988). Conocer los efectos del pastoreo en la diversidad de especies es importante, por un lado, se busca entender las bases del manejo para inducir cambios favorables en la composición de las especies (Daget y Poissonet, 1969;Lauenroth y Laycock, 1989;Sosa-Ramírez y Franco-Vizcaíno, 2001) y por otro, generar una alta diversidad de especies que contribuyan a incrementar la resistencia y recuperación de estas comunidades a disturbios de diferentes magnitud e intensidad (Tilman y Downing, 1996;Society for Ecological Restoration, 2013).…”

Section: Diversidad Y Productividad Del Estratounclassified

Diversidad y Productividad del Estrato Herbáceo en una Sabana de la Sierra Fría, Aguascalientes

Sosa-Ramíre¹,

Núñez²,

Ponce-Montoya³

2015

ANPScripta

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To determine species richness, abundance, and alpha diversity indexes to estimate primary productivity and to obtain rain-use efficiency factor in the savannah ecosystem at the Natural Protected Area Sierra Fria, Aguascalientes, we collected 28 phyto-ecological samples randomly. The floristic composition was determined in an area of 256 m 2 and species abundance in a four-meter line, observing 100 points space out each four cm. We estimate diversity by the Shannon-Wienner index (H´). Four exclusions of 144 m 2 each one were established to measure aerial biomass in the rainy season. Samples were measured with a rectangle of 1000 cm 2 area with four replicates per exclusion. Our results showed 219 species of which 20% were graminae and 6.8% leguminosae.Of the total, 14% were dominant, of which, 17 species were graminae and 13 have some forage value. With respect to alpha diversity index, the lowest value was H'= 3.09 and the highest was H'= 3.87. Mean production of biomass was of 2,330 kg of aerial dry matter per hectare in a year, and an annual mean precipitation of 537 mm. Rain use efficiency (RUE) factor, which is the quotient of annual primary production by annual rainfall, was 4.3 kg ha -1 mm -1. Comparing our results with other regions, richness, diversity was high and the rain-use efficiency factor obtained corresponded to the correct range managed. Species with high forage value were not many and most dominant species had poor forage value.Key words: Rangeland. Primary productivity. Floristic composition. Rain-use efficiency factor. IntroducciónLas sabanas son ecosistemas que proporcionan bienes y servicios como leña, postes y forraje, además son zonas de recreación y cacería cinegética, regulan el ciclo hidrológico y mantienen la diversidad biológica (McPherson, 1997;Puerto, 1997). Así, las sabanas son usadas en forma múltiple, porque se combinan actividades forestales, ganaderas, agrícolas y cacería cinegética; se caracterizan por presentar un estrato herbáceo continuo y un estrato arbóreo o arbustivo disperso.Las plantas leñosas en una sabana pueden variar de 1 a 30% (McPherson, 1997).Las sabanas son extensas y económiamente importantes en regiones templadas y tropicales (Scholes y Archer, 1997). En América del Norte las sabanas se distribuyen principalmente en el

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“…Diversity is important because species reductions or losses are perceived to negatively effect the quality and quantity of ecosystem services (West 1993). On this site, dominance by juniper reduced understory diversity.…”

Section: Post-cutting: Successionmentioning

confidence: 99%

Journal of Range Management, Volume 53, Number 1 (January 2000)

2000

REM

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Biodiversity of Rangelands

Cited by 169 publications

References 73 publications

Global assessment of the non‐equilibrium concept in rangelands

Global assessment of the non‐equilibrium concept in rangelands

Diversidad y Productividad del Estrato Herbáceo en una Sabana de la Sierra Fría, Aguascalientes

Journal of Range Management, Volume 53, Number 1 (January 2000)

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