7 



above "by an alpine growth. 



Undergrowth 



The amount of undergrowth varies greatly and is 

 influenced by exposure and previoue history of the area. 

 It usually holds true that the ground cover is more 

 dense on northern exposures where moisture conditions 

 favor a more luxuriant growth. This is also the case 

 along streams and on areas where there are a number of 

 springs. The undergrowth on these slopes may consist 

 entirely of a dense and almost impenetrable thicket of 

 fir reproduction. Again it may be of one or a number 

 of shrubs such as wild lilac, service berry, manzanita, 

 white thorn, snow-brush or scrub oak. The southern 

 exposures being drier are usually more open and with 

 little or no undergrowth. Areas which have been sev- 

 erely burned over within recent times will in most cases 

 be covered with a dense growth of brush. 



Climatic Conditions in Relation to Fire 



The average rainfall of California varies greatly 

 in different localities, being 70 inches per annum at 

 the northwest corner and less than 3 inches per annum 

 on the Colorado Desert. In the timfeer region, how- 

 ever, the average precipitation is from 30-4-0 inches 

 annually dppending largely upon the elevation. 



