Natural Regeneration 



Characteristic of ponderosa pine forests is the obvious presence of advance 

 reproduction. Seedlings may occur singly or in small or large groups, depending on 

 conditions at the time of their establishment. Advance reproduction is mentioned in 

 ponderosa pine literature as occurring in "waves," interpreted to mean that although 

 small numbers of seedlings may occur from year to year, they are established at 

 irregular and unpredictable intervals in considerable abundance and over areas of 

 several hundred thousand acres or more. This phenomenon of a wave of natural seedling 

 establishment, aided by higher than usual moisture and cool temperatures, occurred in 

 central Idaho in 1963 (Foiles and Curtis 1965a), the first instance since 1941. The 

 classic example, in Arizona in 1919, was the only one during a 38-year period between 

 1908 and 1945 (Pearson 1950) . 



The presence of some established advance reproduction may give the impression that 

 considerable numbers of seedlings are established almost annually. Unfortunately, 

 successful coincidences of ample germinable seed and favorable growing conditions can- 

 not be relied on because they cannot be effectively predicted. If, however, a heavy 

 seed crop is in evidence, the forester may consider several logging methods that provid 

 for natural regeneration in different ways. Mien advance reproduction is present, 

 carefully planned harvest cutting is needed to protect the young stand from excessive 

 logging damage. 



Seed Dissemination 



Whatever the reproduction cutting method, seed must be disseminated from trees on 

 or near the area to be regenerated. The precise time that seed will be disseminated 

 and the distance that it will travel from seed trees vary widely. Weather at the time 

 of seed maturation and dissemination, heights and positions of seed trees, topography 

 and altitude of the location, nature and duration of the air turbulence during dissemi- 

 nation, and degree of cone persistence all affect the time, place, and quantity of 

 seed fall. In a central Idaho bumper crop, 254,000 seed per acre fell in virgin forest 

 203,000 per acre in a selectively cut stand (with residual volume of 4,047 board feet 

 per acre), and 243,000 per acre in a 70-year-old second-growth stand (U.S. Forest 

 Service, Intermountain Forest and Range Exp. Stn. 1937). In western Montana, ponderosa 

 pine seed reached the ground at the rate of 104,000 per acre in a selectively cut 

 stand with residual pine volume of 4,760 board feet per acre (Squillace and Adams 1950) 



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