Biogeoclimatic zones and homology

[John Grehan]

The biogeoclimatic zones described by Ron Kaneen are indeed arbitrary
biogeographic units. The units are defined by a selected feature enclosed by
a "line" representing the geographic limits of that feature (or some kind of
approximation of that limit). Such area concepts are very popular. Whether
they are worth the effort I don't know.

An biogeoclimatic area may be defined by a particular feature
such as the range of a particular plant group or combination of plants, and
for that feature the range is certainly recognizable, but the area itself has,
in my opinion, any "natural' homology in terms of the orgin and evolution of
distributions.

Such areas may be considered "useful" in some pragmatic, political, or
ideological sense, but again these do not, in my view, constitute
criteria for natural homologies involving origins of biogeographic patterns.
The areas thus designated may, however, be interpreted or evaluated by
biogeographic analyses that do not use the areas themselves as units of
classification and information. In New Zealand much time and money was
spent on creating so-called ecological areas when in fact such areas had
no empirical existence. They were called "ecological" yet a particular
ecology was supposed to stop at a line, and an individual ecology was
treated an homogenous (defining) for a particular singe geographic area.

Robin Craw presented the view some years ago that the area of endemism
concept (and the related concepts of biomes, bioclimatic zones, conservation
areas, natural areas etc) is conceptually related to terms and units
developed under
Roman imperial rule where geographic division of the landscape was used to
impose authority and control over the landscape and its resources. Though no
longer explicit, it is possible that such ideology underlies much of
biogeographic
classification based on similar principles (that the distribution of
biodiversity
is divided and fragmented).

John Grehan