I've been recently introduced to the Holdridge life zones and their method of classification, and have been somewhat concerned/confused by the definitions of tropical rain forest as described by the system.

From looking at the zone of tropical rain forest, as opposed to subtropical rain forest or tropical wet forest, the minimum annual precipitation for the category appears to be 8000mm/8m. However, I've also found a number of mentions that the Holdridge system considers a "true tropical rainforest" to have annual temperatures over 24 degrees Celsius and annual rainfall higher than only 2000mm/2m.

The former threshold seems extremely high - very, very few places on Earth, even looking specifically within regions in the Amazon or SE Asia, appear to experience 8000mm or more of annual rainfall. However, an area with above 24 degrees annual temperature and between 2000mm and 4000mm of annual rainfall would appear to be considered a "tropical moist forest" and between 4000mm and 80000mm a "tropical wet forest", separate categories from the "tropical rain forest".

This seems like a very simple definitional question, but I've been unable to find a clear, solid answer on it. Thus:

  • Is it correct that "true tropical rainforest" and "tropical rain forest" are not referring to the same thing, when discussing the Holdridge life zones classification?
  • Are there any appreciable regions in the world that are considered "tropical rain forests" rather than "tropical wet forests", "subtropical rain forests", etc. under the Holdridge classification?

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