1905] WHITFORD—FORESTS OF FLATHEAD VALLEY 12! 
ous forests occur as edaphic formations in the summer-green climatic 
formation. In this region they are xerophytic formations (societies) 
forming a stage in the progression toward the climax mesophytic 
deciduous forest formation. With the wearing down of the xero- 
phytic hills, the filling up of swamps, and the accumulation of humus 
on the sandy plains and hills, the coniferous societies which now 
prevail there will give way to the climax deciduous forest, which is 
the highest expression of a climate similar to that found in the east- 
ern United States.*? 
The Pacific coast district north of San Francisco, and including 
the moister mountainous regions inland, presents a climate entirely 
different from that of the eastern United States. Here, as compared 
with the eastern deciduous forest region, there is a more equable dis- 
tribution of temperature throughout the year, with winter rains and 
excessively dry summers. The forests here are coniferous, with the 
deciduous element occupying only edaphic situations along water 
courses. It is my belief that in some such climate as that found in 
the Puget Sound region the coniferous forest is at its best, the 
deciduous type being unable to compete with it because of the dry 
summers. 
The climate and character of the vegetation of the Pacific coast 
region corresponds more nearly with ScHIMPER’s sclerophyllous wood- 
land (pp. 464-469, 507-540) than they do with his summer-green cli- 
mate and vegetation. Indeed, elements of the sclerophyllous vegeta- 
tion are found in the Puget Sound district, for here such trees as Arbu- 
tus Menziesii show a type of leaf decidedly like that found in climatic 
districts which ScummpeER has so aptly called sclerophyllous woodlands. 
The sclerophyllous formations are in a climate with winter rain and 
comparatively high and equable temperature. Likewise the Pacific 
coniferous district has winter rains and a comparatively equable 
temperature, that is rather warm winters and cool summers. How- 
ever, the mean average monthly temperature is much lower than 
that of the sclerophyllous districts of the warm temperature belt. 
This is no doubt influential in bringing about the narrow type of 
evergreen leaf rather than the broad type found in the warmer climate. 
*2 See ScHIMPER (p. 545) for table showing rainfall of Atlantic forest district and 
Pacific coast 
