484 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



As the flora of the Montane Zone is mostly made up of different 

 pines and Pseiidotsiiga mucronata it may be called the Belt of 

 Pines and Red Fir. 



The upper limit of this zone I have placed at the upper limit of 

 the Bull Pine in Colorado, for here the Douglas Spruce and Lodge 

 Pole Pine extend far up into what I regard as the Subalpine Zone. 

 In the Northern Rockies it may be placed at the upper limit of 

 the Red or Douglas Fir and that of most of the immigrants from 

 the Cascades. This means an altitude of about 10,000 feet in 

 Colorado, 8,000 in the Yellowstone Park and 6,500 feet in northern 

 Montana. The zone so limited would extend north to Lat. 55°, 

 though the Lodge-Pole Pine extends about 10° further north. 

 Of the trees belonging to the Canadian Zone of the East, the 

 Banksian Pine extends in a similar way further north than the 

 other members. The lower limit has been placed at the lower 

 limit of the Lodge-Pole Pine. This is also near the lower limit 

 of the Limber Pine and that of the Douglas Spruce, east of the 

 mountains. The lower limit of the Montane Zone is therefore 

 about an altitude of 7,500 or 8,000 in Colorado and 5,000 feet in 

 southern Montana. It is rather lower on the western side, about 

 4,000 feet in western Idaho. For some reasons to be mentioned 

 later it might have been better to have set the lower limit further 

 down, perhaps at the lower limit of the Douglas Spruce, which 

 would carry it 1,500 feet further down. 



IV. Submontane Zone 



This corresponds mainly to Dr. Merriam's Transition Zone. 

 It has scarcely anything in common with the Transition Zone of the 

 East, the Alleghanian hardwoods, with oaks, chestnuts, walnuts 

 and hickories; but even Dr. Merriam did not regard it as a life 

 zone proper, but a transition belt between the boreal and austral 

 zones. Seen from such a view it is a transition zone between the 

 wooded mountains and the grass-covered plains or between the 

 Roeky Mountains proper and the Sonoran highland. 



Merriam included also in his Arid Transition Zone the plains 

 of the western Dakotas, northern Montana, part of Saskatchewan 

 and Albtrici. lie was correct so far, but did not extend it far 

 encHigh soutli. 1 shall discuss this further on under the headings 

 of the Great Plains. 



