Geoscience Reference
In-Depth Information
drain? Can one 'scale down' from a large or slow process to a smaller or faster
scale in a simple, linear fashion, or not? How can a relationship identifi ed at a
small scale be extrapolated 'up' to larger scales? Multiscale analyses, and the study
of cross-scale linkages, aim to address questions such as these. In order to do this,
scientists classify phenomena into various levels based on the scales at which they
can be observed or measured: the organism level and the community level in
ecology, for example. The spatial and temporal units of measurement appropriate
for each level tend to coalesce in a pattern: larger areas with longer time-periods,
smaller areas with shorter time-periods (fi gure 7.1). Whether such levels are onto-
logically real or merely artifacts of observation can only be determined by empiri-
cal research.
It is easy to see how level and scale might become confused, since they are inter-
changeable
in this sense of scale.
In common usage, for example, one can generally
refer to 'the urban level' as 'the urban scale' without loss of meaning (even though
the extent
of this level may vary depending on historical and geographical context).
Epistemologically, scale as level involves choices of what will and will not be
observed and analysed: A study conducted at 'the community scale' focuses on
phenomena of certain (more or less determinate) spatial and temporal dimensions,
and it may choose to ignore (or hold constant) processes at other levels for the
purposes at hand.
Of course, phenomena that scientists classify at different levels do interact with
one another in the real world, and studies of such interactions require some kind
of ordering principle among levels. Various metaphors have been used: a pyramid,
ladder, scaffold, or the famous 'Russian doll' of nested, recursive systems (Herod
Large
scale
Long-term
climate
change
10
5
10
4
Disturbance
regimes
10
3
Tree
replacement
10
2
10
1
Small
scale
Inseeding
10
1
10
3
10
6
10
9
Area (sq.m)
Figure 7.1
The hierarchy of space-time scales. The space/area and time/rate of
processes tend to co-vary, lending support to the notion of hierarchically ordered
levels in space-time.
Source:
Sheppard and McMaster (2004, p. 12), reproduced with
permission.
