270 'clarence f, korstian 



of the living ground cover as the clearest indicator of the site. 

 Although Cajander admits that in virgin forests the composi- 

 tion of the forest itself correlated with the living ground cover 

 is the best criterion of the physical conditions of growth, he 

 further maintains that in forests which are under the influence 

 of man the living ground cover alone may serve as a criterion 

 and indicator of the physical conditions of the site. The latter 

 statement is at variance with American ideas because of the 

 failure to correlate the living ground cover with the different 

 physical conditions of growth and the failure to appreciate the 

 effect of the varying density of the forest cover on the living 

 ground cover. 



In pointing out the value of the native vegetation as a cri- 

 terion of the potential productivity of land and its application 

 to modern land classification, Pearson^ maintains that a forest 

 may be regarded as the aggregate effect or the summation of 

 the physical conditions obtaining on the site on which it grows 

 and that the consideration of the potentiality of the land need 

 not be confined to the trees. Shrubs, herbs and even the lower 

 forms of plant life may be correlated effectively with the physi- 

 cal factors of the site and also with the tree growth. Pearson 

 concludes that the simpler and more reliable basis for the deter- 

 mination of the adaptability of the site for different crops con- 

 sists in the use of characteristic forms of the native vegetation 

 as indicators of the physical conditions of the site. 



Mason^ reports the abundance of huckleberry {Vaccinium 

 scoparium) on the poorer lodgepole pine (Pinus contorta) sites 

 of the Rocky Mountains. Alder {Alnus tenuifolia) and willow 

 frequently occur as underbrush in moist situations of the same 

 forest type. 



Clements" in discussing the vegetative succession on burned- 

 over areas in the lodgepole pine forest of the central Rocky 



^ Pearson, G. A. What is the Proper Basis for the Classification of Forest 

 Land into Types? Proc. Soc. Amer. Foresters 8: 79-84. 1913. 



* Mason, D. T. The Life History of Lodgepole Pine in the Rocky Mountains. 

 rj. S. Dept. of Agri. Bui. 154, pp. 11-12. 1915. 



^ Clements, F. E. The Life History of Lodgepole Burn Forests, U. S. Dept. 

 of Agri., Forest Service Bui. 79, 56 pp. 1910. 



