FOREST ZONES AN"D FOPJIATIONS 101 



10 or 11 inches. The average heights attained are more sig- 

 nificant. Those for the yellow pine at the end of 1, 2 and 4 

 ■years were respective! j' 2, 4 and 18 inches; for the white pine 

 1, 3 and 9 ; for the lodgepole 1, 4 and 18 ; for the larch 1, 8 and 

 40; for the spruce 1, 2 and 6 and for the Douglas spruce 1, 4 

 and 12 inches. The disadvantages of delayed growth in compe- 

 tition with other species are of course obvious and these are most 

 pronounced in the earliest stages of growth in each species. As 

 between these species it will be seen that the greatest growth 

 in height occurs in those most intolerant. 



In the study of these seedlings parallel experiments were 

 conducted under a lath screen of half shade, 8 feet above the 

 soil. Under such conditions growth was usualty slower than in 

 the open, apparently indicating the retarding effect of shade in 

 the growth of young trees. This result, however, was reversed 

 in the case of the larch and Douglas spruce which exceeded in 

 height those grown in the open. 



Thus in the case of the seeding habits of various species 

 peculiar conditions obtain which affect their prosperity under 

 the varying circumstances of their environment. Probably few 

 features in the life are so intimately concerned with their preva- 

 lence as are those of their seeding habits. 



The Foothill Vegetation. 



Over a large area of western Montana, from the Divide 

 westward to the Bitter Root Range and embracing the 

 drainage of the Clark's Fork and its tributaries the Bitter 

 Root, the Blackfoot and the lower Flathead, the landscape 

 is strongly diversified by alternate forest and prairie. Forest 

 distribution is in strong relation to topography, sheltered 

 slopes are forested, open and exposed slopes are grassy. The 

 latter are usiially, but not always southern or western, often 

 sharply marked in contrast with a vigorous forest at the turn of 

 a ridge which leads to a northern or eastern slope. High slopes 

 rising 2000 feet as in the Plellgate Canyon are thickly wooded 

 on the north with an abrui.)t transition at the crest to grassland 

 on the southern face. Such alternation of forest and prairie 

 are common and on a lesser scale mav be seen in miles of land- 



