Size Structure and Seed Production in Even-Aged Populations of Ceanothus Greggii in Mixed Chaparral

Zammit, Charles; Zedler, Paul H.

doi:10.2307/2261528

Cited by 47 publications

(54 citation statements)

References 30 publications

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“…To describe inequality in plant size, several studies (Creed, Kain, & Norton, 1998;Ditommaso & Watson, 1997;Zammit & Zedler, 1993) Wilson & Gurevitch, 1995). For plants, Damgaard and Weiner (2000) calculated the Lorenz asymmetry coefficient for data from Shumway and Koide (1995) to interpret the effect of mycorrhizae and plant density on the number of capsules produced by Abutilon theophrasti (Fam.…”

Section: Discussionmentioning

confidence: 99%

Body size inequality of carabids along an urbanisation gradient

Magura¹,

Tóthmérész²,

Löveï³

2006

Basic and Applied Ecology

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SummaryAnalysis of size inequality can shed light on coexistence mechanisms and help to interpret patterns in assemblages. We tested several measures for their power to evaluate changes in carabid body size along an urbanisation gradient (city park-suburban area-rural), representing decreasing intensities of human disturbance. Carabids were collected by pitfall traps over two full activity periods in lowland oak forest patches in and near the city of Debrecen, Eastern Hungary.The average value of skewness was largest in the urban areas compared to the suburban and rural ones, indicating that small individuals were more prominent in the urban areas. The Gini coefficient also decreased from urban towards rural areas, suggesting that inequality in body size of the carabid assemblages decreased along the gradient. However, neither of these trends was significant. The Lorenz asymmetry coefficient was significantly higher in rural areas compared to suburban and urban areas indicating that there was a significant difference in inequality and/ or asymmetry of body size across the gradient. This difference was primarily due to more individuals with larger body size in rural area. We suggest that the observed variation in carabid body size along the gradient is related to habitat alteration caused by urbanisation.

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Section: Discussionmentioning

confidence: 99%

Body size inequality of carabids along an urbanisation gradient

Magura¹,

Tóthmérész²,

Löveï³

2006

Basic and Applied Ecology

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“…However, the patch may contain a seedbank or some other dormant form of the life cycle (Zammit & Zedler, 1993). Such patches could also be thought of as refuges from predators or pathogens where the plant can survive but cannot reproduce.…”

Section: The Modelmentioning

confidence: 99%

Patch Dynamics and Metapopulation Theory: the Case of Successional Species

Amarasekare

Possingham

2001

Journal of Theoretical Biology

145

118

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We present a mathematical framework that combines extinction-colonization dynamics with the dynamics of patch succession. We draw an analogy between the epidemiological categorization of individuals (infected, susceptible, latent and resistant) and the patch structure of a spatially heterogeneous landscape (occupied-suitable, empty-suitable, occupied-unsuitable and empty-unsuitable). This approach allows one to consider life-history attributes that influence persistence in patchy environments (e.g., longevity, colonization ability) in concert with extrinsic processes (e.g., disturbances, succession) that lead to spatial heterogeneity in patch suitability. It also allows the incorporation of seed banks and other dormant life forms, thus broadening patch occupancy dynamics to include sink habitats. We use the model to investigate how equilibrium patch occupancy is influenced by four critical parameters: colonization rate, extinction rate, disturbance frequency and the rate of habitat succession. This analysis leads to general predictions about how the temporal scaling of patch succession and extinction-colonization dynamics influences long-term persistence. We apply the model to herbaceous, early-successional species that inhabit open patches created by periodic disturbances. We predict the minimum disturbance frequency required for viable management of such species in the Florida scrub ecosystem.

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“…It is an iteroparous shrub with heavily scleriWed evergreen leaves and explosively dehiscent capsules (Keeley 1977). Plants are readily killed by Wre and depend entirely on the seed bank for population regeneration after Wre (Keeley 1987b(Keeley , 1992Zammit and Zedler 1993). Seeds germinate mainly after winter rains following summer or fall Wres, although L. R. Fox (unpublished data) has found a few new seedlings in unburned areas protected from browsers.…”

Section: Study Systemmentioning

confidence: 99%

Indirect interactions between browsers and seed predators affect the seed bank dynamics of a chaparral shrub

Deveny

Fox

2006

Oecologia

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Interactions between herbivores and seed predators may have long-term consequences for plant populations that rely on persistent seed banks for recovery after unpredictable fires. We assessed the effects of browsing by deer and seed predation by rodents, ants and birds on the densities of seeds entering the seed bank of Ceanothus cuneatus var. rigidus, a maritime chaparral shrub in coastal California. Ceanothus produced many more seeds when protected from browsers in long-term experimental exclosures than did browsed plants, but the seed densities in the soil beneath browsed and unbrowsed Ceanothus were the same at the start of an intensive one-year study. The density of seeds in the soil initially increased in both treatments following summer seed drop: while densities returned to pre-drop levels within a few weeks under browsed plants, soil seed densities remained high for 5-8 months beneath unbrowsed plants. Rodent abundance (especially deer mice) was higher near unbrowsed plants than >30 m away, and rodents removed Ceanothus seeds from dishes in the experimental plots. At least in the short term, rodent density and rates of seed removal were inversely related to the intensity of browsing. Our data have management implications for maintaining viable Ceanothus populations by regulating the intensity of browsing and the timing, intensity and frequency of fires.

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Size Structure and Seed Production in Even-Aged Populations of Ceanothus Greggii in Mixed Chaparral

Cited by 47 publications

References 30 publications

Body size inequality of carabids along an urbanisation gradient

Body size inequality of carabids along an urbanisation gradient

Patch Dynamics and Metapopulation Theory: the Case of Successional Species

Indirect interactions between browsers and seed predators affect the seed bank dynamics of a chaparral shrub

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