SECOND GROWTH YELLOW PIXE. 

 By W. H. Gallaher. 



Western Yellow Pine (Pinus ponderosa) is usually considered 

 a tree of slow but long continued growth whose potential pro- 

 ductive capacity is limited by lack of soil moisture, and therefore 

 one whose maximum yield will always be of an unsatisfactory 

 nature. In mixed virgin forest its distribution is apparently de- 

 termined by root competition for moisture rather than by crown 

 competition for light. Growth studies in such stands have shown a 

 mean annual production per acre which is almost dishearteningly 

 low and an age of maturity which is correspondingly high. Nev- 

 ertheless, under certain conditions it can and does grow with 

 almost astonishing rapidity, comparing not unfavorably with other 

 fast growing species such as White Pine in the east. Loblolly 

 Pine in the south, or Douglas Fir in the northwest. Such con- 

 ditions are found in California where a most fortunate combina- 

 tion of natural and artificial factors has caused the development 

 of considerable areas of second-growth forest. 



Second growth Yellow Pine occurs on the west slope of the 

 Sierra Nevada Mountains in regions where the early gold rush 

 caused the rapid development of mining centers depending on 

 the surrounding country for fuel and lumber. Here typical 

 frontier towns grew up in the typical manner. The exploitation 

 of the virgin timber, much of which was of a quality unexcelled 

 in the state, was rapid and thorough. But the early mushroom 

 growth soon subsided and the area of heavy cutting was fol- 

 lowed by a period of quiescence offering a golden opportunity 

 for the regeneration and growth of a new forest. 



Typical stands of second growth Yellow Pine are now found 

 in the vicinity of Nevada City, Nevada County, California, be- 

 tween the elevations of 2,000 and 4,500 feet. This is a region of 

 great fertility. The rich soils originating from the andesitic lavas 

 of the Neocene, the diabase and granodiorite of the Jura-triassic, 

 or the clay slate of the Carboniferous periods, support a luxuri- 

 ant growth of vegetation. The climate, though varying greatly 

 with the elevation, is in general temperate and is characterized 

 by heavy precipitation during the winter and by dry warm sum- 

 mers. The average rainfall varies from 35 inches in the foot- 

 hills to 65 inches in the high Sierras. Snow may remain upon the 



