66 



INTRODUCTION TO PLANT GEOGRAPHY 



[chap. 



the altitudinal limit on mountains. Altogether they probably play 

 a role in constituting higher vegetation on land, which is second only 

 to that of the other, last remaining group which we shall discuss 

 next. Moreover, their economic importance is in keeping with such 

 a position, for besides affording shelter and greatly affecting Man's 

 environment, they provide him with a large proportion of his timber, 

 pulpwood, turpentine, firewood, and numerous other commodities, 

 besides minor foods and other items of everyday or local life too 

 numerous to mention. 



(See p. 67.) 



