18 Forestry Quarterly 



The humus, which is formed from the yearly fall of leaves from 



the brush, due to its hygroscopic character, increases the water- 

 holding capacity of the soil. Humus also acts like a cultivator in 

 that it keeps the soil loose and flocculated, and for this reason, too, 

 the soil will hold more water. The litter and leaves from the 

 brush, and the brush itself, forms a cover for the soil which 

 prevents evaporation. In consequence, not only does the soil gain 

 more water but it loses less. This is very important on account 

 of the long dry season. Brush affords the young seedling a cer- 

 tain amount of shade, which, while of minor importance to the 

 moisture element, may be likened to the shade of the mother 

 trees in the forest which prevents excessive transpiration through 

 the leaves. 



site; considerations in planting 



Before going into the details of the work, a brief discussion 

 of the site conditions under which this planting must be done 

 may be in order. Especially is the discussion of climate important 

 to show why fall planting is necessary. The most characteristic 

 elements of the climate of this region are : (1) a long dry season ; 

 (2) regular fall rains; (3) frosts during the growing season, and 

 (4) a heavy snowfall. Of these the first two are of the greatest 

 consequence. Only 2 per cent, of the total annual rainfall occurs 

 from June 1 to September 30, hence this period constitutes the 

 dry season. The regular fall rains come in the latter part of 

 October and November. Spring planting would subject the young 

 plants to the long period of drought just at the critical period 

 of their growth. Hence fall planting, just preceding the rains, 

 is more desirable, and was in this case resorted to. Frosts may 

 occur at almost any time of the year above an elevation of 5,000 

 feet. At the higher elevations huge snowbanks keep the soil 

 well supplied with moisture until late into the summer. 



The two factors which are apt to cause failure both at the time 

 of planting and subsequently are lack of soil moisture and 

 extreme temperatures. Of the two, the former is the more 

 important. 



Of the two general slopes of the Sierras, the east and the west, 

 the latter is from every standpoint the more favorable. On the 

 east slope there is much danger from drought, due principally 



