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THE VEGETATION OF THE LAMAO FOREST RESERVE. 
By H. N. Wuirrorp. 
(From the botanical section of the Biological Laboratory, Bureau of Science. ) 
INTRODUCTION. 
It is only within the last decade that the science of ecological plant 
geography has come to be recognized as distinct. It is therefore pertinent 
to review briefly the history of its development. Attention will be called 
only to the principal contributions.’ Floristic plant geography will not 
be considered. 
Grisebach * was the first to point out that the unit of vegetation is the 
formation. This he defines as a group of plants which bear a definite 
physiognomy, as a forest,.a desert, or a prairie. Thurman * emphasized 
the necessity of ground water as a basis for classification and Warming ‘ 
first clearly showed the connection between the former and formation, 
whereas Schimper’s® contribution lay in a discussion of the influence of 
the availability of the ground water. Thus salty and cold soils were 
classed with dry ones because their effect upon vegetation is the same; 
viz, all tend to produce xerophytic structures. Up to this time the idea 
of succession, although it had been recognized as an element, had not 
been taken into consideration as a basis for classification. Cowles* was 
the first clearly to show that the dynamic element of vegetation brought 
about a succession of formations and his classification is based on the 
idea that habitat changes with resulting modification in the conditions 
for plant growth and hence an alteration in plant formations to conform 
with the new-physical factors. Adapting to plant formations the modern 
*For an ecological bibliography see Clements, E. ©. Research Methods in 
Ecology. Univ. of Nebraska Pub. Co. (1905). 
' 2Grisebach, A. Bericht iiber die Leistungen in der Pflanzengeographie (1843). 
*Thurman, J. Essai de phytostatique appliquée a la chaine du Jura et aux 
contrées voicines. (1849). 
“Warming, E. Plantesamfund (1895). German edition, translated by Knob- 
lauch (1896). 
* Schimper, A. F. W.  Pflanzengeographie auf physiologischer Grundlage (1898) 7 
English edition, translated by Fischer (1903). sf: 
*Cowles, H. C. The Physiographic Ecology of Chicago and Vicinity. Bot. 
Gaz. (1901) 31: 75. ' 
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