NATURAT. AREAS AND REGIONS 



210 



north — the 3-ellow pine forest merges 

 with the chaparral growth, and at the 

 upper limit, mingles with the firs and 

 cedars in a complex coniferous forest. 

 The yellow pine type covers a greater 

 area than any other in the state and 

 furnishes a large amount of the pine 

 lumlier manufactured. The forests are 

 utilized as far as desirable as a sum- 

 mer pasture for sheep and cattle. The 

 precipitation varies from 18 to 30 in. 

 Temperatures in summer reach a maxi- 

 mum of 95°F. with an average summer 

 maximum of 85°F. and an average winter 

 minimum of 30°F. The average annual 

 temperature is about 45°F. The period 

 of rest ranges from two weeks to four 

 months, and up to 30 per cent of the 

 precipitation occurs as rain. 



MIXED CONIFEROUS TYPE (XR.'i.NSITION) 



The yellow pine type merges gradually 

 at higher elevations into a mixed conif- 

 erous type which includes the western 

 yellow pine as a dominant member but 

 with the sugar pine {Pinus lamhertiana) 

 as its companion. With these white fir 

 {Abies concolor), Douglas fir {Pseudo- 

 tsuga taxifolia) and incense cedar (Liboce- 

 drus decurrens) are also found. In 

 scattered groves, occurs also the big 

 tree {Sequoia gigantea) famous because 

 of its tremendous size. In the central 

 part of the Sierras, the pines, cedar and 

 Sequoia reach their optimum develop- 

 ment, and the forest, without the gloom 

 that usually characterizes dense forests, 

 are light and airy, and offer excellent 

 recreational possibilities. The bulk of 

 this type, as the preceding, lies inside 

 the boundaries of the National Forests. 

 In addition, several National parks are 

 maintained in this type, chief of which is 

 the Yosemite. 



These pine forests include the really 

 valuable commercial pine forests of the 

 state and are being exploited to the ut- 

 most. On private lands, natural con- 

 ditions are quite often badly upset 

 through destructive lumbering and fire, 

 and too often become brushfields until 

 succession can reestablish a forest. On 

 government lands, exploitation is possi- 



ble, but under restrictions that do not 

 permit the destruction of the stand 

 through careful marking of trees for 

 cutting, fire protection, and supervised 

 lumbering. All of this forest area is not 

 accessible now for logging so that small 

 patches will exist for a long time in a 

 virgin condition, but these areas are 

 quite often not typical stands, and are 

 being grazed by both sheep and cattle. 

 The Forest Service is now setting aside 

 small areas of timber which will not be 

 cut or touched in so far as is i)ossible, to 

 serve as miniature virgin forests, as 

 demonstration and experimental areas. 

 Several have already l)een established 

 and more will be set aside from time to 

 time. In addition, the National Parks 

 maintain natural conditions in forest 

 types typical of those being lumbered. 



Precipitation varies from 30 to 70 in. 

 mostly coming as snow, which remains 

 on the ground from November to April 

 or May. The mean annual tempera- 

 ture is around 45° with a mean sum- 

 mer temperature of 65°. In this belt, 

 which runs up to an average elevation of 

 6000 ft., is the zone of maximum precipi- 

 tation in the Sierra region. 



DOUGLAS FIR (TRANSITION OR CANADIAN) 



The Douglas fir type is characterized 

 by almost pure stands of the Douglas 

 fir {Pseiidotsuga taxifolia) associated 

 with the white fir {Abies concolor) in- 

 cense cedar {Libocedrus decurrens), and 

 occasionally with other species. The 

 Douglas fir forms rather dense pure 

 stands in the northern part of the state 

 particularly along the coast range at 

 elevations from 1000 to 4000 ft. In the 

 Sierras proper it is a tree of the mixed 

 forest. Pure stands are confined to 

 north slopes, and cool moist bottom 

 lands, and the coast ranges. The 

 average monthly temperatures do not 

 vary greatly from winter to midsummer. 

 The precipitation is heavy, occurring 

 mainly as rain, though some areas 

 receive considerable snow. Atmos- 

 pheric moisture is high and often forms 

 fogs. The average summer temperature 



