LIMITS AND FEATURES OF THE WHITE PINE FORESTS. 59 



would not be at all excessive. The limits of the Zone of the Yellow 

 Pine are influenced as much or more by the amount of the annual pre- 

 cipitation as by altitude. The ponderosa pine will not endure excessive 

 humidity; therefore the area covered by this section is the one upon 

 which less snow and rain falls than any other in the Coeur d'Alenes. 



ZONE OF WHITE TINE. 



The next section is that of the White Tine. In this zone occur the 

 heaviest and densest forests of the Cceur d'Alenes. Its vertical range 

 lies between 900 meters (3,000 feet) for the lower and 1,400 meters 

 (4,600 feet) for the upper limit. As the mean of the extreme altitudinal 

 limit of the yellow pine as a tree is about 1,200 meters (4,000 feet), we 

 find more or less of an overlapping of the White Pine Zone by that of 

 the yellow pine. The areas on which the White Pine Zone reaches its 

 best development are all the w T et stream valleys and the mountain slopes 

 with a northern exposure. While as a whole the predominating species 

 in this section is the white pine, we seldom find it forming pure growths. 

 Accompanying it are the majority of the conifers of the Coeur d'Alenes, 

 and some species find here their greatest development. These are the 

 cedar, Eugelmann's spruce, Douglas spruce, white fir, and Mertens's 

 hemlock, Western larch in the lower parts of the zone, and the moun- 

 tain form of the black pine in its upper. 



The distinguishing feature of this zone in its vegetative aspect is 

 the denseness of its growth and the great height of many of the trees. 

 The stand of forest is very close; there is a vast amount of vegetable 

 debris, decaying trees, fresh and old windfalls piled upon one another, 

 broken-oft" tree tops, and young trees bent over by the snow and form- 

 ing impenetrable thickets. Very little grass, more often none at all, 

 grows on the ground, which is heavily covered with a humus reeking 

 with moisture and topped oft' with a growth of mosses and liverworts. 

 Multitudes of fungi are everywhere, representing numerous species and 

 genera. In the fall of the year the ground is fairly carpeted with them. 



Densely tangled masses of underbrush abound. The shrubs that 

 form these are commonly various species of willows and alder, thorn, 

 mountain maple, red cornel, the holly-leaved buck brush (Pachystima 

 my r,si nites), and species of elder. 



The number of trees per acre is always considerable, but varies widely. 

 A fair estimate per acre for the bottoms of the canyons would be 000 to 

 700 trees, with diameters from 25 cm. to GO cm. (10 to 21 inches), and 

 2,000 to 3,000 trees, with diameters from 15 cm. to 25 cm. (0 to 10 inches) ; 

 of saplings there are often tens of thousands on the same space in 

 addition to the larger growth. 



ZONE OF SUUALPINE FIR. 



The third section is that of the Subalpine Fir. Its vertical range 

 lies between 1,500 meters (4,900 feet) for the lower limit to 1,700 meters 

 (5,000 feet) for the upper. The boundaries of this zone are intended to 

 7203— IS T o. 1 5 



