CLIMATOLOGY AND VEGETATION IN COLORADO 
. W. W. RoBBINS 
(WITH SEVEN FIGURES) 
To the student of botany, it matters not in what part of the United 
States he lives or in what branch of botanical work he is engaged, the 
state of Colorado is an interesting and attractive area. The general 
inland location of the state, great differences of altitude, of latitude, 
and of topography, are factors which bring about varied climatic 
conditions, resulting in corresponding vegetative differences. It is 
the purpose of this paper to give a general view of the climatological 
conditions of Colorado in their relation to vegetation. The necessity 
of pointing out in ecological and phytogeographical studies the relation 
between the climatology of an area, extended or restricted in its range, 
and the vegetative covering, is being increasingly recognized. The 
climatologist and the field botanist must join hands. Not only is 
the botanist coming to realize his dependence upon a thorough 
knowledge of climatology as a basis for his phytogeographical studies, 
but in a like manner is the climatologist coming to see that the distri- 
bution of the indigenous vegetation will aid him. This fact has been 
recognized by the Maryland Weather Service, which has undertaken 
a botanical survey of that state as a part of its climatic studies. 
Physiography and climatology 
PHYSIOGRAPHY 
TopocraPHy.—The general topographic features of the state are 
given in fig. z. The eastern half of the state is plains. This region 
is limited on the west by the foothills, which extend from the northern 
to the southern borders of the state, following closely the 6000-foot 
contour line. The foothills rise one over the other, extending west 
ward to the main range. The continental divide passes irregularly 
‘in a north and south direction through the state. It is therefore a 
barrier to the east and west distribution of plants. In the mountain- 
ous region there are four large parks or high valleys: North, Middle, 
South, and San Luis parks. They are broad, level expanses of 
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