REPRODUCTION OF WESTERN YELLOW PINE. 139 



overgrazing or other means, particularly on soils which tend to pack 

 on the surface, properly distributed brush is beneficial. Burn- 

 ing the brush favors reproduction on grassy areas, but not where 

 herbaceous vegetation or litter is absent. Under the latter condi- 

 tions burning may become detrimental, particularly on compact soils. 

 The above relationships, though apparently complex, are based upon 

 a few simple and well-known principles. Western yellow pine ger- 

 minates best in a moist but fairly loose loamy or sandy seedbed. 

 Subsequent development of the seedlings is dependent upon an 

 abundance of moisture and sunlight. Decayed organic matter or 

 even thin layers of undecayed grass, needles, and twigs on the soil 

 favor germination; but undecayed litter when over one-half inch 

 in depth interferes with germination and early establishment of 

 seedlings unless rainfall during the first summer is very abundant. 

 The dense mats often created in pulled tops or lopped or scattered 

 brush effectually exclude pine seedlings until this material has rotted 

 down, which requires at least 10 years. Usually, however, there are 

 numerous small spots within a top or patch of lopped or scattered 

 brush in which both surface and overhead cover are just right for 

 germination and growth of seedlings. Theoretically, the seedlings 

 which start in these spots are greatly favored by the conservation of 

 soil moisture and protection against grazing and climatic elements. 

 These conditions are actually realized where there is no herbaceous 

 vegetation, but vigorous types of grass and weeds where abun- 

 dant develop so luxuriantly under the protection against graz- 

 ing as to suppress the pine seedlings. 



A comparison of pulling tops, lopping, and scattering, as they are 

 usually practiced, reveals the same objectionable features in all 

 three methods. Scattering, however, is subject to better control 

 and is therefore generally preferable to either of the other two 

 methods. Piling and burning is recommended for all typical 

 bunch-grass areas, such as prevail on the Coconino, Tusayan, and 

 portions of the Sitgreaves and Apache National Forests, excepting 

 on overgrazed or otherwise denuded clay soils or on steep slopes 

 subject to erosion. Under the last-named conditions and on bare 

 cinders scattering is usually preferable. On sandy or gravelly soils 

 bearing light ground cover, which prevail on the Santa Fe, Carson, 

 Lincoln, and several other National Forests, brush does not create 

 a grass and 'weed menace, though it does interfere with germina- 

 tion. Piling and burning is preferable on such sites, excepting 

 where there is danger of erosion; but aside from the fire menace, 

 there is no serious objection to scattering if properly executed. 



When advance reproduction exists at the time of cutting, piling 

 and burning should be the invariable practice, unless brush is 

 needed to check erosion. Unburned brush among seedlings and 



