LIFE HISTORY OF LODGEPOLE PINE IN EOCKY MOUNTAINS. 



Table 1. — Climate within the lodgepole region — Continued. 





Type of land or forest 

 "at station — timbered 

 or open. 



Ap- 

 proxi- 

 mate 

 period 



on 

 which 

 aver- 

 ages 



are 

 brsed. 



Mean 

 annual 

 snow- 

 fall. 



Killing frost. 



Station. 



Spring. 



Fall. 



Average 

 latest. 



Latest 

 known. 



Average 

 earliest. 



Earliest, 

 known. 



Colorado: 



Below timber line. 



Years. 



21 



23 



4 



5 



11 



18 



20 



3 



8 



24 



5 



15 



6 



10 

 1 

 2 



9 



3 

 4 

 4 

 4 

 6 

 3 

 4 

 3 

 5 



2 



33 

 14 

 33 

 11 

 18 

 3 

 6 

 3 



Inches. 

 46.5 

 96.1 

 157. 4 

 173.2 

 94.0 

 119.5 

 205.4 

 211.5 

 183.5 

 193.9 

 270.7 

 134.9 

 346.5 



134.8 

 321.1 

 223.2 



96.7 



86.9 

 102.0 

 140.9 

 218.8 



73.0 

 126.0 

 156.8 

 153.2 

 181.3 



158.5 



54.7 

 40.4 

 71.1 

 40.6 

 55.2 



101.3 

 70.1 



182.5 



July 10 

 June 17 

 June 16 



( 2 ) 



( 2 ) 

 July 10 



( 2 ) 



( 2 ) 

 May 29 

 July 21 

 ■ ( 2 ) 

 June 15 

 July 18 



June 23 

 ( 3 ) 



0) 



0) 



July 5 



( 2 ) 



( 2 ) 



$ 



( 2 ) 



June 14 



( 2 ) 

 June 21 



C 1 ) 



July 9 

 ( 3 ) 



Aug. 20 

 Aug. 18 

 Aug. 26 



( 2 ) 



( 2 ) 

 Aug. 28 



( 2 ) 



„ (2) 

 Sept. 10 



Aug. 9 



( 2 ) 



Aug. 31 



Aug. 19 



Sept. 8 

 ( 3 ) 



(') 

 (') 







Aug. 3 





...do 



( 2 ) 



Georgetown 



Longs Peak 



Yellow pine (cut over) . 



( 2 ) 

 (') 



do 



( 2 ) 



Columbine 



Engelmann spruce 



( 2 ) 

 Aug. 25 





. ...do 



0) 



Spruce Lodge... 



Engelmann spruce 



( 2 ) 

 Aug. 3 





Above timber line. , . 

 Below timber line 



0) 



Wyoming: 



Centennial 



Aug. 25 



( 3 ) 









Yellowstone Na- 

 tional Park: 

 Fort Yellow- 





May 14 



June 3 



Sept. 19 



Aug. 25 



stone. 

 Tower Falls «... 





















. .do 













. .do 





































do 











do •. 











do 











stone. 5 



do 











Montana: 



Below timber line 



. .do 



May 7 

 May 20 

 May 28 

 June 17 

 June 5 



June 9 

 June 20 



...do 



July 8 

 June 26 



Sept. 28 

 Sept. 17 

 Sept. 7 

 Sept. 6 

 Sept. 15 



Sept. 5 







do 



Aug. 9 







Aug. 14 



Butte 



Below timber line 



Sept. 5 



Pipestone Pass. 





Below timber line 











Fish Creek 















1""' 



, 





1 Midsummer. 



2 No data. 



s Probably reaches freezing every month; no temperature record. 

 * Likely to get freezing temperature any month. 

 6 Freezing temperatures every month in year. 



In southwestern Montana lodgepole occurs at elevations as low as 

 4,500 feet on northern exposures, where there is the greatest atmos- 

 pheric humidity and the least evaporation from the soil. South 

 slopes at this elevation, if timbered at all, usually support only such 

 species as juniper (Juniperus scopulorum) or Douglas fir {Pseu- 

 dotsuga taxifolia), which require less soil moisture than lodgepole 

 and are better constituted to resist transpiration. Lodgepole is found 

 on southern exposures at about 6,000 feet, provided the gradient is 

 less than 10 per cent. A steep south slope is generally too dry for 

 the species. 



At the upper limit of its range lodgepole gives way to other and 

 more tolerant trees. Increase in soil and atmospheric moisture en- 

 courages such species as Engelmann spruce {Picea engelmanni) and 



