THE 
AMERICAN NAIURALDI 
VoL. XXXIII. January, 1899. No. 385. 
THE RELATION BETWEEN FORESTRY AND 
~ GEOLOGY IN NEW JERSEY. 
ARTHUR HOLLICK. 
I. PRESENT CONDITIONS. 
THE problems of plant distribution, or, in other words, the 
reasons why certain species, genera, or classes of plants occupy 
certain regions, have long received attention from those who 
have observed the facts. If the earth as a whole be viewed in 
connection with the entire vegetable kingdom, it is at once 
apparent that the most powerful factor in limiting the distribu- 
tion of plants is climate, and that isothermal lines are closely 
identified with lines of plant limitation. If, however, smaller 
geographic areas and smaller aggregations of plants be con- 
sidered, it will at once be seen that climatic conditions alone 
are not sufficient to account for all the facts of distribution 
and limitation which obtain, but that physiographic conditions, 
including altitude, presence or absence of moisture in the 
ground and atmosphere, surface configuration, etc., are among 
the factors which are the most influential. Finally, it may be 
noticed that there are some facts of distribution which are more 
or less independent of both climatic and physiographic condi- 
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