Environmental Engineering Reference
In-Depth Information
Frank Clements of 1916 whereby the plant community is likened to a 'super-organism'
which functions by means of the connections between all organisms in the community.
Most ecologists would probably lie closer to Clements than to Gleason in their views, and
would recognize that there are plant communities that repeat themselves over geographic
space. A plant
Table 20.1 Scales of vegetation and ecosystem
study
Scale
Vegetation
Ecosystem
Large
All vegetation
Biosphere or ecosphere
Vegetation formations
Biomes
Vegetation types
Regional ecosystems
Plant communities
Local ecosystems
Small
Species populations and individuals
Single organism-habitat system
Table 20.2 Scales of organization in biology
Large-scale
Biosphere
Ecosystem
Community
Population
Organism
Organ system
Organ
Tissue
Cell
Small-scale
Protoplasm
community can therefore be defined as 'the collection of plant species growing together
in a particular location that show a definite association'.
Vegetation can be studied at a range of different scales starting at an individual plant
at the lowest level right up to the vegetation of the entire globe, i.e. the biosphere or
ecosphere . The Canadian ecologist Stan Rowe proposed a system of nested levels for
both vegetation and ecosystems. Each level occupies a smaller and smaller area. Table
20.1 shows a modified version of Rowe's system. Biogeographers have historically
studied vegetation at all scales; the larger-scale biomes and formations were popular in
the nineteenth century when the world's surface was first being explored and mapped.
This generalized scale of working has received revived popularity in recent years as our
techniques for studying global systems have improved. For much of the twentieth
century, however, biogeographers focused on the plant community level, as it is a very
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