VEGETATION VS. FLORA |
"The substitution, or the repetition, of similar, almost identical morphological types in different regions separated from each other by oceans or wide areas of land, is a marvelous law of nature" -- Humboldt,
I.Questions in Biogeography
A. Ecological (vegetation, physiognomy, life forms, convergent evolution)
B. Historical (flora, areas, genealogy)
II.Vegetation vs. Flora
A. Alexander von Humboldt (with Bonpland & Kunth)
"Even if nature does not produce the same species in similar climates, nevertheless the vegetation exhibits the most striking visual similarities in habit even in the most distant regions. This phenomenon is one of the most remarkable in the history of organic creations; I say in their history, for even if his intelligence informs man how vain hypotheses concerning the origin of [living] things are, the unsolvable problems of how organisms distributed themselves over the earth does not leave us in peace." (Humboldt, 1850)
1. Humboldt's (1807) 15 groups of plant physiognomy
B. Raunkiaer's (1934) classfication system of growth form
An ecological system of classifying plants using the position of the perennating bud, which provides various degrees of protection during dry or cold seasons.
C. Other ideas:
"Each plant community consists of a definite group of life forms. Each habitat favors certain groups of life forms and almost excludes others. The more extreme the habitat conditions the sharper the selection and the more pronounced are the ecological characteristics of the life forms." (Braun-Blanquet, 1932)
"Quite apart from the influence of climates in the distribution of individual plant species, climate strikes at the structure of vegetation everywhere in the same way, whatever its floristic composition. That is to say, similar climates in widely separated parts of the world induce the emergence of similar kinds of plant formations in the physiognomic sense." (Dansereau, 1951)
