Vegetation Classification
Structural classification of vegetation systems
Botanists have long used the Linnaean system of classification, giving names to individual species
by using their genus and their specific name (binomial nomenclature), such as Eucalyptus regnans
(Mountain Ash).
A hierarchy of taxonomic relationships is established with a species (e.g., E. regnans) belonging to a
genus (Eucalyptus), which belongs to a family (Myrtaceae), which belongs to an order, etc.
This is well and good, but poses a problem in Australia in trying to understand something about
entire plant communities: if you focus on the botanical names of individual species (for more than
20,000 'higher' plants alone), you are unlikely--unless you are a dedicated botanist--to be able to
have the time or brain power to identify anything more than a few of the key species in a limited
number of ecosystems.
Moreover, a focus on species literally risks not being able to 'see the forest for the trees', as a
species-approach to understanding ecosystems may miss the vital point about ecosystems: that
they are more than just the sum of their individual species.
Furthermore, even highly detailed and extensive knowledge about Australian species is likely to
leave you ignorant about species in other parts of the world, and therefore unable to make
meaningful comparisons about ecosystems here compared to elsewhere.
In order to deal with these limitations to the Linnaean system, a method of classifying vegetation
communities based upon easily recognizable features of the communities as a whole has been
developed.
It is known as the structural classification of vegetation systems.
The ecologist Ray Specht developed a system using this approach which has become widely used
both in Australia and overseas.
It is based on three elements:

First, identify the lifeform of the tallest stratum (or layer) of plants in an area (e.g., trees,
shrubs, hummock grasses or other herbs).

Second, determine the height and/or type of vegetation in the tallest stratum (e.g., ‘trees over
30m’, or ‘shrubs, non-sclerophyllous’, etc.).

Third, determine the projective foliage cover of the tallest stratum. This is the percentage of
area which is covered by that foliage (leaves).
For example, in a tropical rainforest (Tall Closed Forest), the projective foliage cover will normally be
about 90-100%, while in a mallee community (Tall Open Shrubland), this coverage is usually less
than 10%.
Table 1 below gives a version of Specht's system.
Table 1: Structural Classification of Vegetation
Projective Foliage Cover of the Tallest Stratum
70-100%
50-70%
30-50%
10-30%
<10%
Life form
of tallest
stratum
Trees
>30m
Trees 1030m
Trees
<10m
Shrubs
>2m
Shrubs (S)
0.25-2m
Shrubs
(NS) 0.252m
Shrubs (S)
<0.25m
Tall Closed Tall Forest
Forest
Closed
Forest
Forest
Low
Low Forest
Closed
Forest
Closed
Scrub
Scrub
Closed
Heathland
Heathland
(N/A)
(N/A)
Tall Open
Forest
Open
Forest
Low Open
Forest
Tall
Woodland
Woodland
Open
Scrub
Open
Heathland
Low
Shrubland
Tall
Shrubland
Shrubland
Dwarf
Open
Heathland
Dwarf
Shrubland
Low
Woodland
Low
Shrubland
(N/A)
(N/A)
(N/A)
Shrubs
(NS)
<0.25m
Hummock
grasses
(N/A)
(N/A)
(N/A)
(N/A)
(N/A)
(N/A)
Hummock
Grassland
Tussock
grasses
Sedges
Closed
Grassland
Closed
Sedgeland
Closed
Herbland
Closed
Fernland
Grassland
Grassland
Sedgeland
Sedgeland
Herbland
Herbland
Fernland
Fernland
Open
Grassland
Open
Sedgeland
Open
Herbland
(N/A)
Herbs
(forbs)
Ferns
(N/A)
Open
Woodland
Low Open
Woodland
Tall Open
Shrubland
Open
Shrubland
Low Open
Shrubland
Dwarf
Open
Heathland
Dwarf
Open
Shrubland
Open
Hummock
Grassland
Very Open
Grassland
Very Open
Sedgeland
Very Open
Herbland
(N/A)
Based on Specht, cited in Recher, H., Lunney, D. & Dunn, I., 1986, A Natural Legacy: Ecology in
Australia, p. 106
(S)—sclerophyllous
(NS)—non-sclerophyllous
(N/A)—not applicable (doesn’t occur naturally)
Specht’s system identifies about 50 categories of vegetation systems in Australia.
Many of these are of very limited occurrence, for example, Closed Fernland. Other vegetation
systems such as Open Forest, Woodland, Hummock Grassland and various Shrublands are
widespread.
While at first glance this system may seem complicated, you only have to be able to recognize
trees, shrubs, hummock grasses (spinifex), tussock grasses (e.g., Mitchell Grass), forbs ('flowers',
herbs that aren't grasses), sedges (grass-like in appearance, but not true grasses) and ferns.
With this done, you can make a quick classification of a plant community into one of the following:





forest/woodland
scrub/shrubland/heathland
grassland/sedgeland
herbland, or
fernland.
Then you can assess more detail, such as projective foliage cover, height of the tallest stratum, and
(for shrub communities only) sclerophyllous/non-sclerophyllous.
The term 'sclerophyll' means 'leather-leafed'. Plants with this leaf characteristic have relatively 'hard'
leaves--quite different in texture from the softer leaves of many Northern Hemisphere plants such as
maples (the emblem on the national flag of Canada), elms, and other broad-leafed species that
enjoy predictably humid climates.
Sclerophylly is a mechanism to help reduce water loss from evapo-transpiration from the leafsurface.
With these in mind, you can classify a plant community without knowing anything about the species
present (in terms of their binomial names).
You can do this not only in Australia, but in most other parts of the world as well.
And since structural features are related to climatic and other environmental conditions (e.g.,
heathlands are often an indicator of extremely infertile soils), then you can start to build up a broader
picture of the nature of the ecosystem you are viewing.
Here are two examples of how to use the table to classify a plant community.
In this view near Kata Tjuta in the N.T., we can see the life-form of the
tallest stratum is small trees: trees not shrubs, because these have a
single stem (trunk or bole), rather than the multiple stems or branches
close to the ground that characterize shrubs. [These trees are in fact
Desert Oak, a member of the Casuarina genus.]
The height of these trees is less than 10 m.
The projective foliage cover is (in the area where the trees are most
prominent) in the 10-30% range.
Therefore we can (by checking with Table 1 above) classify this community
as Low Woodland.
It is only a small patch of Low Woodland because slope/soil changes and
fire regimes have created a mosaic of small patches of different
communities in this region.
In this photo (near Alice Springs), the life-form of the tallest stratum in the
foreground is shrubs (this is despite the couple of small trees on the left in
the mid-distance: the odd exception to the 'tallest stratum' is usually
ignored). [These shrubs are known as 'umbrella bushes' because
kangaroos and other animals use them for shade on hot days.]
The shrubs are less than 2 m in height, but are more than 0.25 m in height.
They are sclerophyllous (you'll have to take my word for that, but most
Australian shrubs are), and have a projective foliage cover of 50-70%.
Therefore this community would be classified as Heathland.
You might again note how on the slopes in the distance, the plant
community changes radically due to different soils and fire regimes.
Try identifying the type of vegetation community based on what you can
see in the photo below. What you can see in this close-up view is what
you see over an extended area in this community.
Try to classify it yourself, and then check your result with the answer
below.
Tussock Grassland
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