The Influence of Intense Selective Browsing by Pocket Mice (Perognathus) on the Spatial Distribution of Polygala deserticum in Baja California

Meehan, Thomas E.; Rundel, Philip W.; Ambrose, Richard; Baker, G.H.; Rappaport, Ann

doi:10.2307/2425114

Cited by 6 publications

(4 citation statements)

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“…The present study shows that these species are playing a much broader role in desert environments, aecting the production of grasses and their seed, litter production and possibly the composition of grass communities. The analogous observation by Meehan et al (1977) that Perognathus sp. were aecting the numbers and distribution of the perennial shrub Polygala deserticum in the southern Mohave Desert through direct herbivory, indicates that the impact of herbivory by desert rodents is not limited to grasses.…”

Section: Mechanism For Keystone Statusmentioning

confidence: 62%

Mechanisms for the keystone status of kangaroo rats: graminivory rather than granivory?

Kerley¹,

Whitford

Kay

1997

Oecologia

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Graminivory by kangaroo rats (Dipodomys spp.) was investigated as a potential mechanism for the keystone role of these rodents in the dynamics of desert grasslands. Experiments confirmed that Ord's kangaroo rats (Dipodomys ordii) cut and consumed a large proportion of the tillers of three Chihuahuan Desert tussock-forming grass species. Field observations indicated that the characteristically cut grass tillers were absent from all-rodent and medium-sized kangaroo rat exclosures, but were frequent in large-sized kangaroo rat and rabbit exclosures, indicating that the medium-sized kangaroo rats (D. ordii, D. merriami) were responsible for grass cutting. Tiller waste as a percentage of peak standing crop ranged from 7% in grassland habitats to 0.7% in Flourensia cernua shrubland. Of the 13 species of perennial, tussock-forming grasses measured, only one, Muhlenbergia porteri, had no tillers cut by kangaroo rats. This study demonstrates that the keystone role of kangaroo rats in Chihuahuan Desert grassland ecosystems is probably the result of their graminivory.

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Section: Mechanism For Keystone Statusmentioning

confidence: 62%

Mechanisms for the keystone status of kangaroo rats: graminivory rather than granivory?

Kerley¹,

Whitford

Kay

1997

Oecologia

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“…Seed destruction.-Higher seed production effort sustained higher predation rates along the complex gradient, contributing evidence of another type of spatial variation in insect herbivore-plant interactions. Herbivore pressure (or plant defense) has been shown to vary within habitats (Janzen 1970, 1971b, Platt et al 1974, Handel 1976, Meehan et al 1977, between habitats (Huffaker and Kennett 1959, Rochow 1970, Janzen 1971a, b, c, 1975a, b, Stanton 1975, Bentley 1976, Louda 1978, or between geographic areas (Reichert 1958, Barnes 1968, Wapshere 1974, Levin 1976. The causes of higher intensity seed predation at the coast may include different levels of: (a) genetic (ecotypic) or physiological susceptibility, or (b) insect seed predator activity at the coast.…”

Section: Mllla~nlmentioning

confidence: 99%

Distribution Ecology: Variation in Plant Recruitment over a Gradient in Relation to Insect Seed Predation

Louda¹

1982

Ecological Monographs

325

241

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Abstract. Although predispersal seed predation by insects is common, no test exists of its effect on plant recruitment. This study examines seed predation in the population dynamics of a native, temperate shrub, Haplopappus squarrosus H. and A. (Asteraceae), over an elevational gradient in the coastal sage scrub vegetation of San Diego County, California USA. Frequency and abundance of H. squarrosus increase from coast to mountains. Expected abundance, based on flowers initiated, was highest at the coast and lowest in the interior, the opposite of the observed adult plant distribution. Overall flower and seed predation by insects was high (44-73%) and was greatest at the coast. Insect exclusion experiments at sites along the gradient had three main results. (1) Seedling recruitment was proportional to the number of viable seeds after seed predation. The exclusion plots had significantly higher numbers of seedlings established at all sites than did control plots; the greatest increase was at the coast. (2) Seedling survivorship was independent of both seedling and adult densities. (3) Juvenile recruitment was proportional to seedling establishment. Predation by insects prior to release of seeds played a critical role in the population recruitment of H. squarrosus within and among sites along the gradient. Survivorship of established plants, in addition, was as high at the coast as it was in the interior. These results suggest that indigenous insect seed predators can be a major force controlling the dynamics of a native plant species over its natural distributional range.

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“…Also, because kangaroo rat cutting was recorded for a total of 19 grass and six forb species, this largely unrecognised phenomenon is not restricted to a few grass species, nor is it restricted to monocotyledons (cf. Meehan et al, 1977), but is in fact reasonably general.…”

Section: Defoliation Impacts On the Grassesmentioning

confidence: 94%

Can kangaroo rat graminivory contribute to the persistence of desertified shrublands?

Kerley

Whitford

2009

Journal of Arid Environments

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The Influence of Intense Selective Browsing by Pocket Mice (Perognathus) on the Spatial Distribution of Polygala deserticum in Baja California

Cited by 6 publications

References 0 publications

Mechanisms for the keystone status of kangaroo rats: graminivory rather than granivory?

Mechanisms for the keystone status of kangaroo rats: graminivory rather than granivory?

Distribution Ecology: Variation in Plant Recruitment over a Gradient in Relation to Insect Seed Predation

Can kangaroo rat graminivory contribute to the persistence of desertified shrublands?

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