Editing Biome (section)

==== Whittaker's parameters for classifying biome-types ====
Whittaker used what he called "gradient analysis" of [[ecocline]] patterns to relate communities to climate on a worldwide scale. Whittaker considered four main ecoclines in the terrestrial realm.<ref name="Whittaker1975"/>
# Intertidal levels: The wetness gradient of areas that are exposed to alternating water and dryness with intensities that vary by location from high to low tide
# Climatic moisture gradient
# Temperature gradient by altitude
# Temperature gradient by latitude

Along these gradients, Whittaker noted several trends that allowed him to qualitatively establish biome-types:
* The gradient runs from favorable to the extreme, with corresponding changes in productivity.
* Changes in physiognomic complexity vary with how favorable of an environment exists (decreasing community structure and reduction of stratal differentiation as the environment becomes less favorable).
* Trends in the diversity of structure follow trends in species diversity; alpha and beta species diversities decrease from favorable to extreme environments.
* Each growth-form (i.e. grasses, shrubs, etc.) has its characteristic place of maximum importance along the ecoclines.
* The same growth forms may be dominant in similar environments in widely different parts of the world.

Whittaker summed the effects of gradients (3) and (4) to get an overall temperature gradient and combined this with a gradient (2), the moisture gradient, to express the above conclusions in what is known as the Whittaker classification scheme. The scheme graphs average annual precipitation (x-axis) versus average annual temperature (y-axis) to classify biome-types.