Shrub encroachment affects mammalian carnivore abundance and species richness in semiarid rangelands

Blaum, Niels; Rossmanith, Eva; Popp, Alexander; Jeltsch, Florian

doi:10.1016/j.actao.2006.10.004

Cited by 98 publications

(79 citation statements)

References 38 publications

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“…Responses of animals to WPE vary broadly by taxa, plant community, and geographic region, but ultimately responses can vary by species (Ayers et al 2001;Meik et al 2002;Blaum et al 2007a;Blaum et al 2007b;Blaum et al 2009). Species-specific responses are expressed frequently as sharp transitions in the probability of occupancy (i.e., changes in distribution) or as changes in demographic rates such as density, survival, or reproductive success at specific levels of woody plant cover (Grant et al 2004;Sirami et al 2009).…”

Section: Animalsmentioning

confidence: 99%

Woody Plant Encroachment: Causes and Consequences

Archer

Andersen

Predick

et al. 2017

Springer Series on Environmental Management

384

379

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Woody vegetation in grasslands and savannas has increased worldwide over the past 100-200 years. This phenomenon of "woody plant encroachment" (WPE) has been documented to occur at different times but at comparable rates in rangelands of the Americas, Australia, and southern Africa. The objectives of this chapter are to review (1) the process of WPE and its causes, (2) consequences for ecosystem function and the provision of services, and (3) the effectiveness of management interventions aimed at reducing woody cover. Explanations for WPE require consideration of multiple interacting drivers and constraints and their variation through time at a given site. Mean annual precipitation sets an upper limit to woody plant cover, but local patterns of disturbance (fire, browsing) and soil properties (texture, depth) prevent the realization of this potential. In the absence of these constraints, seasonality, interannual variation, and intensity of precipitation events determine the rate and extent of woody plant expansion. Although probably not a triggering factor, rising atmospheric CO 2 levels may have favored C 3 woody plant growth. WPE coincided with the global intensification of livestock grazing that by reducing fine fuels, hence fire frequency and intensity, facilitated WPE. From a conservation perspective, WPE threatens the maintenance of grassland and savanna

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Section: Animalsmentioning

confidence: 99%

Woody Plant Encroachment: Causes and Consequences

Archer

Andersen

Predick

et al. 2017

Springer Series on Environmental Management

384

379

View full text Add to dashboard Cite

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“…This usually is accompanied by decreased herbaceous biomass (Eldridge et al 2011). More variable ecosystem changes that have been linked to shrub encroachment are the loss of mature trees (Herrmann and Tappan 2013), decreased plant (Ratajczak et al 2012) and animal biodiversity (Meik et al 2002, Blaum et al 2007, Kaphengst and Ward 2008, increase in bare soil (D'Odorico et al 2012), and a loss of ecosystem services (De Klerk 2004). Thus the classic model of shrub encroachment is commonly associated with land degradation.…”

Section: Introductionmentioning

confidence: 99%

Examining the linkage between shrub encroachment and recent greening in water‐limited southern Africa

2015

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Abstract. There have been reports of widespread increases in satellite-derived vegetation indices in drylands across the globe. At the same time, there are numerous field-based observations of increases in the density of small woody plant species, a process known as shrub encroachment. We compare groundbased observations of shrub encroachment with information from 14 years of Tropical Rainfall Measuring Mission (TRMM) precipitation data, Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) and MODIS land cover data for southern Africa, focusing on areas that receive less than 1000 mm of precipitation per year. Cumulative precipitation and maximum NDVI were computed for each year and linear regression analysis was used to correct for interannual variability in precipitation. Accounting for precipitation effects, we found an underlying, overall greening in southern Africa, with NDVI increasing þ3.34% on average over the 2000-2013 study period. Over 15% of the region is undergoing statistically significant change, strongly biased towards greening. The strongest greening was in a coherent band stretching from northern Namibia to Lesotho. Ground-based reports of shrub encroachment tend to overlap with strong greening; we suggest that these processes are linked. Reports that intersect our period of record showed overwhelmingly positive trends, indicating that our method is suitable for detecting shrub encroachment. Shrublands and savannas accounted for 78% of the study region. Savannas did not change appreciably (À0.21% total change) from 2000-2013 while shrublands were greening faster than any other land cover type over the same period (þ8.93%). Fast rates of greening in this biome may be indicative of shrub expansion. Large-scale shrub encroachment will have important consequences for dryland degradation and global carbon dynamics.

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“…This is serious because fragmentation diminishes biodiversity (Collinge et al, 2003), given that species composition on a patch will depend on its size and isolation (Crooks, 2002). Some of the negative effects of disturbances that have been reported are the following: soil fertility loss and erosion (Wezel and Rath, 2002), less vegetative (Nikiema, 2005) and fauna diversity (Blaum et al, 2007), favoring the establishment of invasive species (McDougall and Turkington, 2005) and brush encroachment (Van Auken, 2000), amongst others.…”

Section: Introductionmentioning

confidence: 99%

“…Although these activities have been considered to have low environmental impact, Pérez-Negrón and Casas (2007) suggested that, in some communities, cactus fruit collection can total 151 kg/year and wood extraction for fuel can be more than 400 tons/year. Therefore, these activities have the potential to shift species diversity and composition resulting in direct species loss (Osem et al, 2002) or favoring the establishment of invasive species, either exotic or native (Valéry et al, 2004;Blaum et al, 2007) that could be used as indicator species.…”

Section: Introductionmentioning

confidence: 99%

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Diversidad vegetal a lo largo de un gradiente de perturbación en un ecosistema semi-árido en el Centro de México

Ramírez-Bravo

Hernández-Santín

2016

Acta Bot. Mex.

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Antecedentes y Objetivos: La fragmentación del hábitat y otras alteraciones humanas pueden causar la pérdida de fertilidad del suelo, erosión y la pérdida de biodiversidad, entre otras; sin embargo, la información en zonas áridas es limitada. El objetivo de este trabajo fue determinar los efectos de un gradiente de disturbio en la composición de especies en dos tipos de vegetación en un ecosistema semi-árido del centro de México.Métodos: Se seleccionaron seis zonas de estudio diferentes en la zona de Cerro Colorado, tres de matorral xerófilo y tres de bosque tropical caducifolio. Se determinó la diversidad genérica y específica utilizando 10 cuadrantes (un total de 60), localizados al azar, durante los meses de mayo-junio de 2011. Se generó un índice de perturbación basado en las actividades que se registraron en la región como pastoreo y tala, entre otros. Las áreas de alto, medio y bajo disturbio se identificaron en el matorral xerófilo y bosque tropical caducifolio.Resultados clave: Los resultados mostraron que el bosque tropical caducifolio es más diverso que el matorral xerófilo, además de que es posible utilizar a los arbustos Cnidoscolus tehuacanensis y Mimosa luisana como indicadores, ya que se encontraban en lugares con altos niveles de perturbación. Por otro lado, en el bosque tropical caducifolio, tres géneros (Thevetia, Acacia y Bursera) presentan altas abundancias relativas en lugares conservados, mientras que en el matorral xerófilo solo uno (Parkinsonia) tiene este patrón.Conclusiones: De los resultados se puede inferir que en hábitats semiáridos del Centro de México las actividades antropogénicas juegan un papel importante en la diversidad florística, ya que facilitan el establecimiento de algunas plantas nativas que pueden ser consideradas como colonizadoras. Estas pueden ser utilizadas como indicadoras de los disturbios con la finalidad de determinar la viabilidad de hábitat para otros taxa.

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Shrub encroachment affects mammalian carnivore abundance and species richness in semiarid rangelands

Cited by 98 publications

References 38 publications

Woody Plant Encroachment: Causes and Consequences

Woody Plant Encroachment: Causes and Consequences

Examining the linkage between shrub encroachment and recent greening in water‐limited southern Africa

Diversidad vegetal a lo largo de un gradiente de perturbación en un ecosistema semi-árido en el Centro de México

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