Summary 



This paper summarizes present information on natural and artificial regeneration 

 of ponderosa pine in the territory served by the Intermountain Forest and Range Experi- 

 ment Station. In this area, ponderosa pine grows under a wide range of conditions 

 typified by varying rainfall, high temperatures, and low humidities during the growing 

 season, mountainous topography, and great diversity of soil types and depths. It is a 

 climax or serai species in 11 habitat types, ranging from warm and dry to cool and moist. 



The ease with which ponderosa pine can be regenerated varies with conditions; 

 therefore, no single regenerative technique can be employed with success everywhere. 

 Some generalities, however, apply in varying degrees to ponderosa pine stands through- 

 out the Intermountain Station territory. 



Some kind of site preparation is necessary to establish either natural or arti- 

 ficial regeneration. Because soil moisture is a critical factor in seedling establish- 

 ment, competition from other vegetation must be effectively reduced. Techniques 

 include hand scalping, mulching, use of herbicides or fire, and machine stripping 

 and terracing. 



Planting has become an established method of regenerating brushfields and timber 

 sale areas. Several planting systems are used successfully. Trees may be planted by 

 hand or by machine on well-prepared sites. Seed source, for either direct seeding or 

 planting, must be carefully chosen. Seed supply varies widely from year to year. 



Direct seeding has never been used as extensively as planting in this region, 

 although some seedings on favorable sites have been successful. The major factors in 

 successful seeding are good site preparation, and protection from seed-eating rodents 

 and birds. 



In planting, healthy nursery stock and care in handling and field planting are 

 essential . 



Successful natural regeneration of ponderosa pine depends on a combination of 

 abundant seed supply and minimum competing vegetation. Good cone crops occur irregu- 

 larly so site preparation may have to be delayed to coincide with a heavy seed crop. 

 In years of heavy seed crops, several high forest methods of reproduction cutting have 

 been shown to produce sufficient seed for regeneration; seed-tree, shelterwood, group 

 selection, and stem selection cutting have been tested. These methods are successful 

 to varying degrees, depending partly on the habitat type of the stand location. 



Numerous natural forces cause mortality of trees of different ages. Squirrels, 

 chipmunks, and mice are responsible for the greatest losses in seed and can harvest 

 most of the seed crop in light and medium years. The chief cause of seedling loss 

 during the period of establishment and after germination or planting is drought, which 

 often accounts for more than half of total mortality in the first 3 years. These 

 losses can be reduced by rodent control measures, adequate site preparation, or timely 

 weedings and thinnings. Other causes of mortality, such as fire, insects, diseases, 

 and animals, are more sporadic. Control of these forces requires regular surveillance 

 and prompt action when required. 



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