Critical Scale Concepts

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Critical Scale Concepts

• Jennifer M. Coffer
• Geography 610
• November 30, 2003

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• the problem of relating phenomena across scales
  is the central problem in biology and in all of
  science
• -- Levin, 1992

www.in-cities.com
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Broad Scale Environmental Concerns

• Acid rain
• Global Climate Change
• Habitat Fragmentation
• Biodiversity

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• Scale refers to the spatial and/or temporal
  dimensions of an object or a process
• Spatial Dimension space
• Temporal Dimension time

Turner,2001
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rst.gsfc.nasa.gov
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sorrel.humbolt.edu
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Characteristics of Scale

• Grain Finest level of spatial resolution
  possible within a given data set
• Extent Size of the study area or the duration
  of time under consideration

Turner, 2001
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Scale Terminology

• Absolute Scale the actual distance, time, or
  area
• Relative Scale scale that describes the
  relative distance, direction or geometry based on
  some functional relationship

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Resolution

• - Precision of measurement grain size, if spatial

www.msss.com
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Three Scale Issues- Haggett (1963)

• 1. The Scale Coverage Problem
• - The surface of the Earth is so large that its
  enormity posed difficulties in mapping and
  understanding the spatial variability

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• 2. The Scale Linkage Problem
• Direct consequence of the scale coverage problem
• The relation of relatively fine-scale data to a
  broader spatial scale.

www.tripod.com
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• conclusions derived from studies made at one
  scale should not be expected to apply to problems
  whose data are expressed at other scales.
• every change in scale will bring about the
  statement of a new problem, and there is no basis
  for assuming that associations existing at one
  scale will also exist at another.
• - McCarty (1956)

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• 3. The Scale Standardization Problem
• Most social data were reported for areas rather
  than points and that these areas vary widely in
  size and shape, both between and within
  countries.
• -Haggett 1963

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Identifying the Right Scale

• That there is no single correct scale or level
  at which to describe a system does not mean that
  all scales serve equally well or that there are
  not scaling laws.
• - Levin, 1992

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Scaling Up

• Challenges
• Correctly defining the spatial and temporal
  heterogeneity of the fine-scale information
• Correctly integrating or aggregating this
  heterogeneity to the broader scale
• -King, 1991

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Conclusions

• Scales must be selected based on the question or
  objective of a study.
• Methods of scale selection remain a current
  challenge in geographic research.

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Bibliography
Delcourt, H.R., P.A. Delcourt, and T. Webb,1983.
Dynamic plant ecology the spectrum of vegetation
change in space and time. Quaternary Science
Review 1153-175. King, A.W. 1997. Hierarchy
theory a guide to system structure for wildlife
biologists. In J.A. Bissonette, ed. Wildlife and
Landscape Ecology. Effects of Pattern and Scales,
pp.185-212. Springer-Verlang, New York. Levin,
S.A. 1992 The problem of pattern and scale in
ecology. Ecology 731943-1983. Schneider, D.C.
1994. Quantitative Ecology. Spatial and Temporal
Scaling. Academic Press, San Diego,
California. Turner, M.G., Gardner, R.H., and R.V.
ONeill, 2001. Landscape Ecology in Theory and
Practice., Springer-Verlang New York, Inc. Wiens,
J.A. 1989. Spatial Scaling in ecology. Functional
Ecology 3385-397.
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Questions?