Ecology and Resource Management

Watt, Kenneth E. F.; Oster, George

doi:10.1115/1.3426571

Cited by 149 publications

(89 citation statements)

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“…Diffusion equations, such as ( 2.1 ), are often applied in studies on the spatial spread of populations (Okubo 1986;Williamson and Brown 1986;Lubina and Levin 1988;Andow et al, preprint;Kallen et al 1985;Caughley 1970;Watt 1968;Noble 1974). Although much insight is gained, there is an inherent…”

Section: On Onmentioning

confidence: 99%

The velocity of spatial population expansion

1990

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Abstract. We consider the velocity with which an invading population spreads over space. For a general linear model, originally due to Diekmann and Thieme, it is shown that the asymptotic velocity of population expansion can be calculated if information is available on: (i) the net-reproduction, ~; i.e. the expected number of offspring produced by one individual throughout its life, and (ii) the (normalized) reproduction-and-dispersal kernel, {J(a, x -e); i.e. the density of newborns produced per unit of time at position x by an individual of age a born at e. By means of numerical examples we study the effect of the net-reproduction and the shape of the reproductionand-dispersal kernel on the velocity of population expansion. The reproduction-and-dispersal kernel is difficult to measure in full. This leads us to derive approximation formulas in terms of easily measurable parameters. The relation between the velocity of population expansion calculated from the general model and that from the Fisher /Skellam diffusion model is discussed. As a final step we use the model to analyse some real-life examples, thus showing how it can be put to work.

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Section: On Onmentioning

confidence: 99%

The velocity of spatial population expansion

1990

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“…He sug gests an abstraction of the real world situation into mathematical Models are a means of studying complex phenomena (Forrester 1964 Van Dyne (1969) and Watt (1968) suggest the use of models as a tool to better understand the entire ecosystem. Indeed, if such a large undertaking is accomplished it will have to be done with the use of some simplifying abstraction.…”

Section: Advances In Modellingmentioning

confidence: 99%

Root Dynamics of a Shortgrass Ecosystem

Bartos¹,

Sims²

1974

Journal of Range Management

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OF DISSERTATION ROOT DYNAMICS OF A SHOR TGRASS ECOSYSTEMSeasonal dynamics of roots of a shortgrass system were deter mined by samples collected at two week intervals for two growing seasons (1969)(1970) with a fall and winter sampling period in between.Soil cores were taken to a depth of either 10 cm or 80 cm; the deep cores were used to determine the entire profile distributions of roots.The cores were washed free of soil particles and then the root mass was dried, weighed, ashed and reweighed. All values were expressed on an ash-free basis.Sixty percent of the root weight was in the 0-10 cm segment and 75% was found in the upper 20 cm of the soil profile. The upper 10 em increment had significant variations between dates, but the lower levels remained quite constant.Four grazing treatments (none, light, moderate, heavy) were used to determine if grazing had an effect on the root mas s. No significant differences were found among the four treatments.The usual concept of substrate storage in roots and subsequent

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“…In recent years there has been a proliferation of simulation models applied to several areas of renewable resource management (e.g., Paulik and Greenough, 1966;Watt, 1968;Walters and Bunnell, 1971;Walters and Gross, 1972;Gross et aZ., 1973;Clark and Lackey, 1974;Walters et aZ., 1975). However, few of these attempts to infuse systems techniques into resource management have met with wide acceptance among the decision-makers who were the potential clients.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Environmental Assessment and Management

1980

Forest Science

540

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Ecology and Resource Management

Cited by 149 publications

References 0 publications

The velocity of spatial population expansion

The velocity of spatial population expansion

Root Dynamics of a Shortgrass Ecosystem

Adaptive Environmental Assessment and Management

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