32 



NORTH A:\[ERT('AN fatxa. 



[NO. 16. 



not the two actually iiitei-jjiade, while an iiiterestiii<>' qnestion, is of 

 little coiiseriueiice com[)aied with the fact that here, as in the Sierra, 

 the two trees occupy adjoining but distinct belts — ponderoHa the warmer 

 and noniinlly the lower; Jefreiji the colder and normally the hiji^her. It 

 sonu'tiines hai»[)ens, however, as in i)laces alon<i' the cold east base of 

 the Scott Mountains, where local conditions produce abnormal tempera- 

 tures, that a stri]) of Jeffrey pine is sandwiched in between two areas 

 of ponderosa i)ine. In this instance the low temperature^ comes in part 

 from the coolinji' effects of cold streams, and in part from the afternoon 

 shadows of the mountains. 



The ponderosa forest is nowhere pure over any large area, but is 

 sprinkled in varying i)ro[)ortion with sugar ]>ines, incense cedars, 

 Douglas lirs, and white firs, and at lower altitudes with black oaks. 

 The stately sugar pines are so valuable for lumber that the best have 

 been already cut, but enough remain to show that the species was 



formerly common in most 

 parts of the i)onderosa for- 

 est. The incense cedars 

 also are scattered over the 

 whole region, butthe Doug- 

 las and white firs require 

 more moisture and conse- 

 (juently are less evenly dis- 

 tributed. They ;ire most 

 abundant on the borders 

 of streams, in cool canyons, 

 and along the M'ell- watered 

 east base of .Mount Eddy and the Scott ^lountain.s, where they become 

 the dominant trees, the ]>onder<)sa pines being coinitaratively scarce. 

 On drier an<l warmer soil, away from the cooling intiuence of the Scott 

 Mountains, the ponderosa pines ra[)idly increase, and in the area 

 betw<^en Black IJutte, Shasta Valley, and the mountain, although 

 sprinkled with incense cedars aiul black oaks, they Ibrm the purest 

 ponderosa forest of the region. 



Another conifer of the yellow-])ine belt is the knobcone ])ine {Pi)iiis 

 attennafa), a narrow interrupted tongue of which ])ushes up Panther 

 Creek. The deciduous trees of this belt are the black oak {(Jtiemis 

 caJifornic(()j Oregon maj)le (.Leer nKicropJijiUu))!). tree alder {Aliuifi 

 fenui/olia), and Oregon dogwood [Coriiux nvtf((lli). The maple and 

 dogwood are restricted to the lowest levels :uid do not occur in very 

 dry places: the alders are conlined to the neighborliood of water: the 

 oak ranges more widely over tiie lower half of the pine l)elt and tliri\('s 

 on dry as well as f)n modeiately moist soils. 



The conifers will be considered as individual species. 

 Sugar Pine {Pimis lumhcriiana). — The sugar i>ine is the hirgest, 

 handsomest, and noblest of our wcvstein pines, and its wood is so 



Fig. 16. — CoDes of ponderosa and Jelirey pines. 



