GC In Ean Blas 
TRUE CHAPARRAL. 
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True chaparral is one of the types of a plant formation which 
occurs in several widely separated parts of the world. The forma- 
tion is known to plant ecologists as sclerophyllous woodland. It 
may be described (though not defined) as a mixed forest of stunted 
trees, and is the result of peculiar climatic conditions. As one of 
the intermediate forms between a flourishing forest and a desert, it 
represents a sort of balance between certain environmental extremes. 
At this balance the growth is dwarfed, and the full-grown trees at- 
tain only the dimensions of brush, even low brush. 
The dwarfing of tree growth results from deficiency of moisture and 
one or more other conditions, such as excessive transpiration, barren 
soul, high altitude, and wind. As we advance into high latitudes or 
climb to corresponding altitudes, the trees diminish in stature, until 
we find only struggling procumbent or bushy forms of the most 
cold-enduring species of trees—species which, at lower latitudes or 
altitudes, were of good forest size. A similar phenomenon is ob- 
served as we advance toward regions of desert conditions, but the 
result is a dwarf forest of an entirely different kind. 
Inasmuch as each species of tree has a given set of moisture and tem- 
perature conditions under which it does best, the composition of any 
forest—and the composition determines the type—varies with both 
these conditions. Leaving out of account, for the immediate pur- 
pose of this discussion, such other factors as soil constituents and 
soil structure, it is easy to see that any given set of climatic condi- 
tions will exclude from the forest all but a certain number of 
species, which are capable of competing with each other under the 
given conditions. 
The combination of conditions in parts of southern California 
results in a selection of certain species to form a dwarf forest which, 
on the one hand, leaves out the species generally characteristic of 
northern latitudes, and, on the other hand, the distinctively tropical 
vegetation. It includes neither the species characteristic of Canada 
nor those characteristic of the lowlands of Mexico. It is therefore 
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