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THE NATIONAL GEOGRAPHIC MAGAZINE 



tion. Plant life there can stand freezing 

 without difficulty. It is rather the thaw- 

 ing process that hurts in such regions. 

 The wonderful adaptability of plant 



life to its environment is to he seen on the 

 tundra of Russian Lapland. There the 

 thermometer crosses the freezing point 

 several times a day, but the leaves on the 

 stunted growth that occurs in spots do 

 not seem to suffer. So, too, in the Alps 

 some species of gentian and ranunculus, 

 even when in full blossom, spend their 

 nights frozen stiff and their days as bright 

 and chipper as if they had never known 

 a chill moment. 



These flowers have adjusted themselves 

 as thoroughly to the cold at timber-line 

 as the cactus has to the heat in the trop- 

 ical desert. And the trees are led by 

 riiese "little children" of the timber-line 

 in adjusting themselves to the inhospi- 

 tality of their environment. 



The character of the warfare on the 

 sea-level polar timber-line differs from 

 that on tropical mountain heights. On 

 the former there is a homogeneity of 

 forces not encountered in the latter. 



Everywhere on the polar timber-line the 

 trees without exception become stunted 

 and dwarfed, degenerating into gnarled 

 growths that little resemble their stately 

 brethren of milder regions. Neither the 

 broad-leaved nor the needle-leaved spe- 

 cies, as a rule, attains a height of more 

 than three feet. 



The: march of the tree hosts up a 

 mountain side; 



The mountain timber-line, however, 

 has highest interest for most people, 

 since it is in a theater of war accessible 

 to any hardy mountain-climber, who, as a 

 military observer, may wish to watch the 

 great battle. 



A hundred romances are concentrated 

 in the story of the march of the trees up 

 the mountain side toward the battle front. 

 Far down on the plain out of which rises 

 a tropical mountain like Orizaba, in Mex- 

 ico, there is luxuriant vegetation. If the 

 rainfall is plentiful, it grows abundant on 

 the lower slopes. Palms and bananas are 

 the characteristic trees of the first two 

 thousand feet. 



However, when that elevation is 

 reached these have largely given place to 



the tree-ferns and figs, which, with allied 

 species, now take up the climb, and 

 "carry on" until they come to the 4,000- 

 Foo1 level. Ih-re they, in turn, begin to 



drop out, their places being filled by 

 laurels, myrtles, and related species. 

 These drive on another 2,000 feet, giv- 



ing wav, m their turn, 



the broad-leaved 



evergreens, which take up the climb at 

 about 6,000 feet and march on until they 

 reach 8,000 feet. Gradually they fall by 



the wayside and their ranks are filled by 

 the summer-green broad-leaved tree. 



At 10,000 feet the conifers fill up the 

 gaps and finally arrive at the trenches. 



In many mountains there are varia- 

 tions in the vertical distances to which 

 the different trees climb, and in some 

 cases one or another of the list of reser- 

 vists is almost entirely missing. It is a 

 singular fact that the various types of 

 trees are able to climb higher on moun- 

 tain ranges than on isolated peaks, and 

 that, as a rule, the timber-line is higher 

 on long ranges than on short ones, as if 

 confidence and courage were imparted by 

 a dense formation of fellow-fighters. 



THE WAR CORRESPONDENTS OE THE 

 TIMBER-UINE BATTLE FRONT 



The great contest at timber-line, as in 

 human warfare, has called forth a large 

 number of war correspondents. One of 

 the ablest of these was John Muir, whose 

 love of Nature is an inspiration for every 

 one who reads his books. And the best- 

 loved part of Nature to him was that 

 wonderful country, the Sierra region of 

 the Pacific Coast. 



Like the true war observer, he wrote 

 with equal charm of the larger strategy 

 of a big drive and of the brave deeds of a 

 single warrior. For him the whitebark 

 pine had a particular interest, not less 

 from the methods of its fighting than for 

 the unwonted heights to which it bravely 

 climbs. 



In the Yosemite mountain forests he 

 found it always in the front-line trenches. 

 Where he first encountered it on the 

 march up the mountain it was an upstand- 

 ing tree trooper, some forty feet high; 

 but as he followed its footsteps up to the 

 regions where, on the rocky, wind-swept 

 slopes, the snow lay deep and heavy for 

 half the year, it grew shaggy and squat, 



