30 NORTH AMERICAN FAUNA. [no. 16. 



covered with dwarf trees is that tliese sl()])es are in their zone ])osition 

 truly alpine and above tin.berline, as already exi»lained. 



Nothing is easier than to refer to the wrong zone species found in the 

 treeless basins between the pine-covered ridges. But when it is under- 

 stood that parts of each basin, regardless of the distance below the 

 highest tongue of timber, are unquestionably aborr timbcrline (and con- 

 sequently Alphie) and that other i)arts, regardless of the distance above 

 the nearest trees in the basin, are unquestionably well heJo^r tini])erline 

 (and consequently llii(ho)tia)i), mistakes of this kind will be less 

 frequent. 



THE FORESTS OF SHASTA. 



Shasta rises from a forested region (pi. v), and the mountain itself is 

 continuously forest-covered up to an altitude of 7,500 or 8,000 feet. The 

 trees of the lower slopes are those of the surrounding region, but those 

 of the middle and upper sIojjcs belong to such widely different species 

 that it is necessary to divide the mountain forest into three belts, which, 

 from their most distinctive trees, may be designated (1) the lower or 

 yellow-pine belt; (2) the middle or Shasta lir belt, and (3) the up])er or 

 white-bark pine belt. It is interesting to observe that these forest 

 divisions, as shown later, coincide with the tliree Life zones — the 

 Transition, Canadian, and ITudsonian. 



(1) The Lo-wer Belt or Belt of Yellow or Ponderosa Pmes (Phms jionderona). 



The most abundant and characteristic tree of the lower slopes and 

 surrounding region is the yellow or ponderosa pine, which forms a con- 

 tinuous open forest up to an altitude, on the south and west sides, of 

 about 5,500 feet. The only material gap in tlie pine belt of the moun- 

 tain proper is a strip about 8 miles in length on the cold northeast 

 quadrant, which is occupied by lodge-i)ole pines belonging to the zone 

 above (Canadian zone). 



On the south and west the open pine forest of the basal slopes is 

 interrui)t('d by extensive i)arks, which from a distance appear to be 

 meadows of waving grass. A nearer view shows this to be an illusion, 

 the broad fields of green being in reality impenetrable thickets of 

 chaparral — a chaparral of unyielding manzanita and buck brush 

 (Arc(o.st<(jtlii/l<>s pat Ilia and Ceanothus rrliitiniis, see tig. 15). 



Nortliwest of Shasta, the yellow pine forest is interrujjted by the open 

 plain of Shasta Valley, which on the southwest ends abruptly at the 

 town of Edgewood. North, northeast, and east of Shasta the ponder- 

 osa pine forest continues with uniini)ortant interruptions to Devils 

 Garden, Goose J^ake, and the Madeline Plains; on the south it is prac- 

 tically continuous to the base of Lassen Butte, and thence along the 

 flanks of the Sierra for 350 miles; on the southwest it follows tlie canyon 

 of the Sacramento lliver to a little below Delta, wiiere, in the bottom 

 of the canyon and on its wanner slopes, the curious digger pines of 

 the l'j)i)er Sonoian zone nii.x with and soon replace the jmnderosa pines 



