108 ***** "O/z, Ranger!" 



Life zones are groups of plants and animals living together in agree 

 able communities. Making a trip from the San Joaquin Valley in Cali 

 fornia through Sequoia National Park to the summit of Mount Whitney 

 is the equivalent of making a journey from Mexico to the Arctic circle 

 at sea level. As many different kinds of plants and animals would be 

 found on this short trip as on vastly longer trips from south to north. 



Most of the national parks, because of their variety of altitude, in 

 clude several life zones. There are five zones in Yellowstone, for ex 

 ample, reaching from the Alpine zone at the top of Mount Washburn 

 and Electric Peak, through the Sub-Alpine zone, the Hudsonian, the 

 Canadian, and the Transition to the Upper Sonoran zone. These five 

 zones account for the wide range of trees, flowers, birds, and animals in 

 the Yellowstone. Almost equally great is the variety of life zones in 

 many of the other parks, each of which offers a special field of study for 

 the ranger naturalist and his staff before they can answer the questions 

 sure to be put to them by visitors. 



"Well, Ranger, how did arctic plants get to Yellowstone from the 

 Arctic circle ?" 



"That is a question which seems to worry a good many people. 

 Sometimes they ask me if the birds bring the seeds when they migrate. 



It is very doubtful if they do. The generally 

 accepted explanation is that North America 

 once had a much colder climate than it now 

 enjoys. When the great glaciers spread over 

 the continent, during the Ice Age, the plants 

 of the Arctic circle naturally were pushed 

 south, while the more tropical plants were 

 either killed off or were pushed still farther 

 south. When the ice blanket melted and the 

 climate became warmer, the cold-loving 

 plants in the south died out or slowly crept north, follow 

 ing the glaciers back to the Arctic circle. Some of these 

 plants, instead of migrating northward, worked up the 

 slopes and, having established themselves comfortably on 

 the mountain tops and finding the climate congenial, stayed 

 there when their comrades followed the ice back to the Arctic circle. 

 Other and more tropical plants came in and surrounded these little belts 

 of arctic plants, isolating them on the mountain tops. 



"These migrations of the flowers and trees form the most fascinating 

 study in the world, once you get into it. A good place to see the flowers 

 migrating is on Mount Rainier, where the glaciers are still retreating, a 

 few feet each year. Each inch they give up is eagerly swallowed up by 

 the army of the flowers, marching up the mountain side. It is said that 



