28 
from the top of a fire tower on the ridge just west of the Pine Lake ranger 
station. The darker green foliage of the poplars and dark points of the 
spruces are just appearing above the tall aspens. The shrub layer loses 
many of the willows, and Shepherdia canadensis, Rosa acicularis, and 
Viburnum paucifiorum become predominant though scattered. A notable 
change occurs in the ground layer by the new growth of the woodland 
mosses and lichens. In the dense shade of the spruces the herb flora is 
reduced to Maianthemum canadense , Rubus pubescens, Pyrola asarifolia , 
Linnea borealis var. americana, and a few scattered grasses. The poplar- 
spruce woods appear to be merely a stage of development of the mature 
spruce timber from the aspen woods, the aspen in turn being introduced 
by burning. 
During the field seasons of 1929-30, the writer had several opportuni- 
ties to observe the initial vegetation that follows new burns. A very 
destructive fire swept a strip of country extending north and south between 
Pine and Moose lakes in 1928, much of it having occurred as late as Octo- 
ber of that year. The first plants to appear in the growing season of 1929 
were the water-leaf Phacelia Franklinii, corydalis Corydalis aurea, gera- 
nium Geranium Bicknellii, dragon’s-head Dracocephalum parvijlorum, and 
the liverwort Marchantia polymorpha. In recently burned spruce woods 
along Little Buffalo river and on the lower slopes of Caribou mountains 
were found large numbers of the sponge mushroom Morchella conica, which 
attains a height of 4 to 6 inches. 
So little clearing has been done that it is impossible to tell the exact 
effects of it. The general effects, judging from the evidences around cabins, 
are not much different from those of a mild burn. The ground cover is not 
removed, and the ensuing timber seems to return rather quickly to its 
former state, wdth a certain amount of intermingling of deciduous species. 
A relatively unimportant influence which is modifying the upland forest 
in small areas is the wallowing activity of the buffalo herds. These ani- 
mals find a favourite resort for rubbing and fighting flies during the summer 
in the open pine w r oods. The lichen mat is not rooted, so that it can be 
easily torn up and the dry sand tossed or used to roll in. The trees are 
slowly being killed by having their bark rubbed off a short distance above 
the ground. The writer has examined no areas in which this process has 
been carried to the extreme, but there are many wallows in the Pine Lake 
district that show minor plant associations introduced by partial clearing. 
The common herbaceous species of cabin clearings throughout the region 
make their appearance upon the stirred ground. Whitlow grass Draba 
nemorosa, chickweed Cerastium nutans , bird seed Lepidium apetalum, and 
strawberry blight Chenopodium capitatum, are the first invaders of new 
wallows. Later comes a miscellaneous mixture of grasses and other herbs, 
such as five-finger Potentilla norvegica var. hirsuta, goldenrod Solidago 
oreophila , chickweed Stellaria longipes var. laeta, fox-tail Alopecurm 
aequalis, blue-grass Poa glauca, and a few others. 
Figure 2 is a map of Pine lake and the vegetation in its vicinity, derived 
partly from the writer's field studies, and partly from aerial photographs. 
The predominance of woodland over semi-open country is manifest, as well 
as the large proportion of the timber which is deciduous. 
