THE CORDILLERAN CLIMAXES. 227 



by a chance spark is of terriffic intensity and rapidity. The ascending heat 

 creates a strong breeze and sweeps the fire along as fast as a horse can gallop. 

 The large quantitites of highly inflammable gases evolved by the heat from 

 the pitchy tree tops catch fire and shoot high in the air as well as far Id advance 

 of the main fire, bridgiag rivers and lakes and starting the fire afresh. This 

 accounts for the incredible speed of most of the larger fires. Some have been 

 known to run at the rate of 15 miles an hour, and thus change the appearance 

 of large tracts of country in a short time. The wild animals in the vicinity of 

 a large forest fire understand in advance the danger proclaimed by the roar- 

 ing noise and clouds of smoke, and flee for their lives, but as a rule are all 

 soon overtaken and destroyed, except such as live in the water, or can reach 

 the water in time. The birds even flying high in the air are stifled and finally 

 fall into the flames. These great flres come to an end in different ways: by a 

 change in the wind followed by rain, or by reaching a wide extent of previously 

 burned country, or of small deciduous trees, or a chain of large lakes. 



"After the fire, the dead trunks of the larger trees generally stand for many 

 years. In the summer following it, the blackened ground becomes partly 

 covered by herbaceous plants, berry bushes, and shoots from the roots and 

 butts of deciduous trees, as well as numerous small seedling trees. The 

 huckleberry bushes spring from large old roots, bear abundant crops of fruit, 

 and are very common for the first few years, though inconspicuous in the 

 former old forest. In 15 or 20 years the ground is covered with poplars, 

 birches, willows, etc., to a height of about 30 feet. Under the mass of fallen 

 timber will be found many healthy young conifers overshadowed by the more 

 rapidly growing deciduous trees. At the end of about 50 years, these become 

 abundant and conspicuous. In competition with the deciduous growth, they 

 develop tall trunks with branches high up. In 100 years, the poplars are dying 

 and falUng down, and the canoe birch has attained maturity and soon after 

 shows old age. Meantime the older conifers have overtopped the other trees 

 and given a new character to the forest. Seedlings are produced every year, 

 and in about 150 years the forest has again become almost entirely con^erous, 

 and is ready to be destroyed again by fire. In these regions, perhaps one-third 

 of the whole area consists of 'second growths' of less than 50 years, one-third 

 of trees from 50 to 100 years old, while the remaining third may be 100 years 

 and upwards. 



" Fire appears to be a necessity in the propagation of the Banksian pine. Its 

 knotty cones are not deciduous, but stick to the tree as long as it lasts, the 

 older crop becoming covered with lichens and showing great age. If the tree 

 dies or falls over and decays, the cones lie about imopened. But when stand- 

 ing trees are scorched by fire, the cones immediately open, and the seeds 

 become scattered far and wide by the wind. Forest fires have probably 

 occurred every year since trees of the present species existed on the continent, 

 and an interesting question arises as to how the Banksian pine acquired this 

 curious habit. Charred wood occurs under great depths of Pleistocene deposit 

 near Toronto, while there is no evidence of the advent of man in Canada until 

 a very recent period." 



WhUford (1905 : 295) has reached the following conclusions as to secondary 

 succession in the forests of northern Montana: 



"1. Fires play an important part in determining the present composition 

 of the forest. 



"2. The lodgepole pine is the 'fire tree' of the region. 



"3. It is favored after fires principally because it has the capacity to pro- 

 duce seeds early in its fife. 



