The Role of Explicit Space in Plant Competition Models

Inter-plant competition models and their sampling distributions

Advances in Applied Probability ◽

10.1017/s0001867800040556 ◽

1975 ◽

Vol 7 (3) ◽

pp. 453-454

Author(s):

Howard Ross-Parker

Keyword(s):

Plant Competition ◽

Sampling Distributions ◽

Competition Models

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Cause and Effect Theories of Attention: The Role of Conceptual Metaphors

Review of General Psychology ◽

10.1037/1089-2680.6.2.153 ◽

2002 ◽

Vol 6 (2) ◽

pp. 153-165 ◽

Cited By ~ 33

Author(s):

Diego Fernandez-Duque ◽

Mark L. Johnson

Keyword(s):

Cognitive Psychology ◽

Information Processing ◽

Crucial Role ◽

Limited Resource ◽

Scientific Concepts ◽

Biased Competition ◽

Cause And Effect ◽

Classic Problem ◽

Competition Models

Scientific concepts are defined by metaphors. These metaphors determine what attention is and what count as adequate explanations of the phenomenon. The authors analyze these metaphors within 3 types of attention theories: (a) “cause” theories, in which attention is presumed to modulate information processing (e.g., attention as a spotlight; attention as a limited resource); (b) “effect” theories, in which attention is considered to be a by-product of information processing (e.g., the competition metaphor); and (c) hybrid theories that combine cause and effect aspects (e.g., biased-competition models). The present analysis reveals the crucial role of metaphors in cognitive psychology, neuroscience, and the efforts of scientists to find a resolution to the classic problem of cause versus effect interpretations.

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Recruitment of Eucalyptus strzeleckii (Myrtaceae) in intensive livestock production landscapes

Australian Journal of Botany ◽

10.1071/bt07187 ◽

2008 ◽

Vol 56 (6) ◽

pp. 469 ◽

Cited By ~ 3

Author(s):

Claire Moxham ◽

Josh Dorrough

Keyword(s):

Seedling Emergence ◽

Plant Competition ◽

Cattle Grazing ◽

Soil Disturbance ◽

Limiting Factor ◽

Understorey Vegetation ◽

Seed Supply ◽

Successful Establishment ◽

Natural Recruitment

Eucalyptus strzeleckii K. Rule (Strzelecki gum) is a medium-to-tall forest swamp gum, endemic to Victoria and listed as Nationally Vulnerable in Australia. This species occurs in the high rainfall (up to 1600 mm) region of Gippsland in south-eastern Victoria. The region has been intensively developed for agriculture, in particular dairy production. Surviving trees are often old and in varying stages of dieback and natural recruitment is rarely observed. The removal of cattle-grazing as a sole mechanism to encourage recruitment is rarely sufficient to promote regeneration of this species. The aim of this study was to examine the role of soil disturbance, weed competition, seed supply and parent plant competition, in the absence of cattle-grazing, in the recruitment of E. strzeleckii. Seed availability, distance from mature tree, soil disturbance, soil moisture and pasture competition all influenced seedling establishment and survival in the field. Removal of ground layer vegetation immediately before seedling emergence appears to be essential for successful establishment of E. strzeleckii. However, both soil disturbance and pasture removal by spraying had similar effects, suggesting that competition rather than soil disturbance per se is a limiting factor in these environments. In the absence of understorey vegetation manipulation, regeneration by this species is unlikely even in the absence of grazing.

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Partitioning the union of disks in plant competition models

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1979.0075 ◽

1979 ◽

Vol 205 (1160) ◽

pp. 423-423

Keyword(s):

Explicit Form ◽

Plant Competition ◽

Boundary Curve ◽

Point Of View ◽

General Point ◽

Continuity Properties ◽

Competition Models ◽

Change Of Scale ◽

The Common

The problem of partitioning the union of disks, which arises in theories of competition between plants, is analysed from a general point of view. Some simple and natural assumptions such as connectedness, invariance under translation, rotation and change of scale, and monotonicity and continuity properties of the partition sets are imposed. From these it is proved that the partition is specified by giving a boundary curve between two disks with the very explicit form: R α x ─ | r ─ x | α = R α y ─ | r ─ y | α , α ≽ 1, where R x , R y are the radii of the disks, x , y are their centres and r is a point on the boundary. This includes the Johnson-Mehl construction (α = 1), the common chord (α = 2) and the perimeter of the larger disk (α → ∞). Larger disks dominate smaller ones if and only if α > 1, so that η = 1 ─ 1/α, 0 ≼ η < 1, is a natural index measuring the strength of domination.

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