Plants as Reef Fish: Fitting the Functional Form of Seedling Recruitment

Poulsen,; Osenberg, Craig W.; Clark, Matt; Levey,; Bolker,

doi:10.2307/4541071

Cited by 24 publications

(43 citation statements)

References 29 publications

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“…This is widely used as a population growth function and has been used to model plant populations [43], with the population after the growth phase being given by the current population u multiplied by the growth rate…”

Section: Analytical Approximationsmentioning

confidence: 99%

Spreading speeds for stage structured plant populations in fragmented landscapes

Gilbert

White

Bullock

et al. 2014

Journal of Theoretical Biology

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Article (refereed) -postprintGilbert, Mark A.; White, Steven M.; Bullock, James M.; Gaffney, Eamonn A. 2014. Spreading speeds for stage structured plant populations in fragmented landscapes.Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Spreading Speeds for Stage Structured Plant Populations in Fragmented Landscapes AbstractLandscape fragmentation has huge ecological and economic implications and affects the spatial dynamics of many plant species. Determining the speed of population spread in fragmented/heterogeneous landscapes is therefore of utmost importance to ecologists. Stage-structured Integrodifference Equations (IDEs) are deterministic models which accurately reflect the life cycles and dispersal patterns for numerous species.Existing approximations to wave-speeds consider only particular kernels, or landscapes in which the scale of variation is much smaller than the dispersal scale. We propose an analytical approximation to the wavespeeds of IDE solutions with periodic landscapes of alternating good and bad patches, where the dispersal scale is greater than the extent of each good patch and where the ratio of the demographic rates in the good and bad patches is given by a small parameter, denoted . We formulate this approximation for the Gaussian and Laplace dispersal kernels and for stage structured and non-stage structured populations, and compare the results against numerical simulations. We find that the approximation is accurate for the landscapes considered, and that the type of dispersal kernel affects the relationship between landscape structure, as classified by landscape period and good patch size, and the spreading speed. This indicates that accurately fitting a kernel to data is important in determining the relationship between landscape structure and spreading speed.

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Section: Analytical Approximationsmentioning

confidence: 99%

Spreading speeds for stage structured plant populations in fragmented landscapes

Gilbert

White

Bullock

et al. 2014

Journal of Theoretical Biology

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“…However, seed and microsite limitation are expected to vary over spatial scales relevant to dispersal because seeds are rarely, if ever uniformly dispersed from the maternal plant. We often see microsite limitation near the maternal plant, and seed limitation becomes more pronounced at increasing distances from the seed source (Clark et al 1998;Poulsen et al 2007). For species with very limited dispersal, this may occur on a scale of meters or less.…”

Section: Introductionmentioning

confidence: 98%

Widespread seed limitation affects plant density but not population trajectory in the invasive plant Centaurea solstitialis

Swope

Parker

2010

Oecologia

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In some plant populations, the availability of seeds strongly regulates recruitment. However, a scarcity of germination microsites, granivory or density-dependent mortality can reduce the number of plants that germinate or survive to flower. The relative strengths of these controls are unknown for most plant populations and for exotic invaders in particular. We conducted a seed addition experiment with a granivore exclusion treatment in a field setting to explore how these factors interact to regulate populations of the widespread invader Centaurea solstitialis (yellow starthistle) at three study sites across the plant's range in California. We coupled the experimental approach with observational studies within established C. solstitialis populations to estimate seed rain, recruitment and mortality at natural densities. Seed limitation occurred in both experimental and observational plots in all populations. Although vertebrate granivores were active at each site, they had no effect on C. solstitialis recruitment. Density increased mortality, but the effect was variable and weak relative to its effect on fecundity. The seed limitation that was evident at the seedling stage persisted to flowering. Seed-limited populations such as these ought to be highly sensitive to losses to seed predators, and many biological control agents, including those established for C. solstitialis, are seed predators. However, flowering plant density was decoupled from seed production by a strong compensatory response in the surviving plants; seed production was nearly constant in plots across all seed addition levels. Thus, flowering plant density is reduced by the established biocontrol agents, but seed production compensates to replace the population every generation, and no long-term decline is predicted.

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“…This is particularly challenging when individuals of at least one life stage disperse great distances between suitable habitat patches. Commonly studied examples include marine sessile invertebrates and sedentary reef fish with planktonic larvae (Connell 1985;Caley et al 1996;Hixon et al 2002), many terrestrial plants with wind-dispersed seeds that descend as ''seed rain'' (Levine and Murrell 2003;Poulsen et al 2007), and stream insects, where aquatic juveniles can disperse along channels and terrestrial adults can disperse across catchment boundaries (Hershey et al 1993;Peckarsky et al 2000;Briers et al 2004;Macneale et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Environmental constraints on oviposition limit egg supply of a stream insect at multiple scales

2010

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Species with complex life cycles pose challenges for understanding what processes regulate population densities, especially if some life stages disperse. Most studies of such animals that are thought to be recruitment limited focus on the idea that juvenile mortality limits the density of recruits (and hence population density), fewer consider the possibility that egg supply may be important. For species that oviposit on specific substrata, environmental constraints on oviposition sites may limit egg supply. Female mayflies in the genus Baetis lay egg masses on the underside of stream rocks that emerge above the water's surface. We tested the hypothesis that egg mass densities are constrained by emergent rock densities within and between streams, by counting egg masses on emergent rocks. All emergent rocks were counted along 1-km lengths of four streams, revealing significant variation in emergent rock density within streams and a more than three-fold difference between streams. In each stream, egg mass density increased with the density of emergent rocks in 30-m stretches. We used regression equations describing these small-scale relationships, coupled with the large-scale spatial variation of emergent rocks, to estimate egg mass densities for each 1-km stream length, a scale relevant to population processes. Scaled estimates were positively associated with emergent rock density and provided better estimates than methods that ignored environmental variation. Egg mass crowding was inversely related to emergent rock density at the stream scale, a pattern consistent with the idea that oviposition substrata were in short supply in streams with few emergent rocks, but crowding did not compensate entirely for differences in emergent rock densities. The notion that egg supply, not larval mortality, may limit population density is an unusual perspective for stream insects. Environmental constraints on egg supply may be widespread among other species with specialised oviposition behaviours.

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Plants as Reef Fish: Fitting the Functional Form of Seedling Recruitment

Cited by 24 publications

References 29 publications

Spreading speeds for stage structured plant populations in fragmented landscapes

Spreading speeds for stage structured plant populations in fragmented landscapes

Widespread seed limitation affects plant density but not population trajectory in the invasive plant Centaurea solstitialis

Environmental constraints on oviposition limit egg supply of a stream insect at multiple scales

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