Use of California Annual‐Plant Forage by Range Rodents

Fitch, Henry S.; Bentley, Jay R.

doi:10.2307/1932612

Cited by 46 publications

(23 citation statements)

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“…nigra , which is unlikely to provide a substantial food source (Bell and Muller 1973, Feeny 1977). Therefore, if this form of apparent competition is occurring, it seems most likely to be mediated through larger consumers whose effects depended on the abundance of exotic grasses (Fig 1) that may form a substantial food resource (Fitch 1948, Fitch and Bentley 1949, Chapman 1974).…”

Section: Discussionmentioning

confidence: 99%

Multiple drivers of apparent competition reduce re-establishment of a native plant in invaded habitats

Orrock

Witter²

2010

Oikos

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Although rarely examined, apparent competition, whereby exotic plants increase consumer pressure on native plants, could play a significant role in affecting native plant establishment in invaded habitats. Moreover, although terrestrial consumer communities often contain many consumer species, little is known about which consumers may generate apparent competition, and whether the strength or mechanism of apparent competition differs among different members of the consumer community. Using consumer‐specific experimental exclosures and seed additions in the invaded grasslands of California, we demonstrate that multiple mechanisms of apparent competition are capable of limiting the re‐establishment of the native grass Nassella pulchra in the absence of direct competition with exotic plants. The effect of small mammalian consumers (mice and voles) and larger consumers (e.g. rabbits, squirrels, deer) decreased with distance to the exotic forb Brassica nigra, which varied from 0–33 meters from focal N. pulchra. The effect of larger consumers also depended upon characteristics of the plant community directly adjacent (i.e. approx. 1 m) from focal N. pulchra. The effect of large consumers also increased with the richness of the exotic plant community and the degree to which the exotic plant community was dominated by exotic grasses as opposed to exotic forbs. Our finding that apparent competition can be driven by different mechanisms, that the importance of each mechanism depends upon which consumers have access, and that each mechanism has a different spatial extent, suggests that the composition of both the consumer community and the exotic plant community may shape the spatial dynamics of reestablishment, the potential for restoration, and the need for conservation.

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Section: Discussionmentioning

confidence: 99%

Multiple drivers of apparent competition reduce re-establishment of a native plant in invaded habitats

Orrock

Witter²

2010

Oikos

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“…On Hastings Reservation in California, when lands formerly grazed were protected from grazing, the densities of California ground squirrels fell precipitously (Linsdale 1946). Studies at the San Joaquin Experimental Range near Fresno, California, showed similar results in that squirrel populations were larger in areas grazed by livestock compared with ungrazed areas (Howard et al 1959;Fitch and Bentley 1949). Other studies have documented higher predation risk for ground squirrels in habitats with high, compared to low, vegetative cover (Schooley et al 1996;Sharpe and Van Horne 1998).…”

Section: Discussionmentioning

confidence: 67%

The Effects of Livestock on California Ground Squirrels (Spermophilus beecheyii)

Fehmi¹,

Russo²,

Bartolome³

2005

REM

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Understanding the impacts of livestock grazing on wildlands is important for making appropriate ecosystem management decisions. Using livestock exclosures, we examined the effects of moderate cattle grazing on the abundance of California ground squirrels (Spermophilus beecheyii Richardson) and the spatial distribution of active burrows within their colonies in grassland and blue oak (Quercus douglasii Hook. & Arn.) savanna habitats in the coastal range of California over a 3-year period (1991)(1992)(1993)(1994). Overall, relative population densities of California ground squirrels declined significantly throughout the experiment, but did not differ between grazed and ungrazed colonies or between habitats. There was also no significant interaction between these 2 factors. The spatial distribution of burrows, as measured by the mean nearest neighbor distance of active entrances within a colony, did not differ significantly between grazed and ungrazed colonies or between habitats, nor was the interaction significant. Thus, low to moderate levels of cattle grazing did not appear to have a strong effect on the population dynamics of California ground squirrels, and grazing may be compatible with maintenance of ground squirrel populations. Based on multivariate analysis of variance of 1994 data, live plant cover, native plant cover, and standing biomass were lower where the number of burrows was higher on grazed colonies but were little affected on ungrazed colonies. Ground squirrels may increase the impact of livestock grazing and thus reduce the capacity of the land to support other activities. However, it is clear that the effects of livestock grazing are complex and that detailed studies of potential mechanisms by which grazing impacts California ground squirrel populations are necessary. ResumenEntender el impacto del apacentamiento del ganado en tierras silvestres es importante para tomar decisiones apropiadas sobre el manejo de los ecosistemas. Durante un periodo de tres añ os (1991-1994) y usando exclusiones de ganado, examinamos los efectos del apacentamiento moderado en la abundancia de ardillas terrestres de California (Spermophilus beecheyii) y la distribució n espacial de madrigueras activas dentro de sus colonias en há bitats de pastizal y ''Blue oak'' (Quercus douglasii) en la regió n costera de California, USA. En general, las densidades relativaas de la població n de ardillas declinó significativamente durante el experimento, pero no hubo diferencia entre colonias con apacentamiento pastoreo y sin apacentamiento, ni entre habitats. Tampoco hubo interacció n significativa entre estos dos factores. La distribució n espacial de madrigueras, medida por la distancia promedio del vecino más cercano de entradas activas dentro de una colonia, no difirio significativamente entre las colonias apacentadas y no apacentadas ni entre habitats, ni la interacció n fue significativa. Así, niveles de apacentamiento bajos a moderados no parecieron tener un efecto fuerte sobre las diná micas de la població n de a...

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“…We observed no apparent increase in ground squirrels on the new BP areas on SFRFS. At densities of 8 or more per hectare, ground squirrels can compete with livestock for forage (Fitch andBentley 1949, Howard et al 1959). Ground squirrels are quail nest predators; Glading ( 1938) attributed 30 nests destroyed by ground squirrels from a total of 96 nests found.…”

Section: Discussionmentioning

confidence: 99%

Economic Relationships of Brushpiles, Forage Production, and California Quail Hunting

Gorenzel¹,

Mastrup²,

Fitzhugh³

1991

Journal of Range Management

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Use of California Annual‐Plant Forage by Range Rodents

Cited by 46 publications

References 0 publications

Multiple drivers of apparent competition reduce re-establishment of a native plant in invaded habitats

Multiple drivers of apparent competition reduce re-establishment of a native plant in invaded habitats

The Effects of Livestock on California Ground Squirrels (Spermophilus beecheyii)

Economic Relationships of Brushpiles, Forage Production, and California Quail Hunting

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