The characteristics of individual seed trees deserve attention. Parent trees that 

 will produce genetically superior progeny cannot always be selected by visual observa- 

 tion. There are guides, however, which suggest some general things to look for in 

 selecting superior trees (U.S. Forest Service 1948"). For reasonable safety, seed should 

 be collected from the better-than-average trees in the stand and from better- than 

 average stands. 



To provide a more abundant and regular seed supply from a known source of good 

 genetic quality, seed production areas have been developed. They are selected to pro- 

 vide seed for a particular area or zone, with a special reference to elevation. On 

 each one, the most vigorous and well-formed trees of an existing stand are released to 

 a spacing of about 30 feet and treated to promote seed production. The effects of 

 spacing, irrigation, fertilization, cultivation, and insect control on seed production 

 need to be determined. The most promising measures will be used to promote seed pro- 

 duction in these stands. 



Eventually, some seed for direct seeding and nurseries will come from seed 

 orchards of selected trees that have demonstrated ability to produce progeny with 

 specific genetic characteristics we value. Desirable characteristics might include 

 resistance to some disease or insect, increased growth rate, improved wood quality, 

 drought resistance, or improved crown quality for esthetic uses such as Christmas 

 trees. The characteristics desired may vary with ownership and locality. 



Seed Production and Storage 



Ponderosa pine is a variable producer of seed, and heavy cone crops occur infre- 

 quently (Curtis and Lynch 1965). In western Montana, only one "good" crop and five 

 "fair" crops were recorded in 23 years of observations (Boe 1954). In central Idaho, 

 three very heavy cone crops were reported from 1935 through 1958 (Curtis and Foiles 

 1961 ) . 



Ponderosa pine trees produce large numbers of cones and seeds in years of heavy 

 crops (fig. 8). For example, cone yields from the very heavy crop of 1936 in central 

 Idaho (table 2) averaged from 222 cones per tree on immature trees to 1,409 cones per 

 tree on mature scattered trees. Seed yields from the same crop averaged from 16,100 

 seeds per immature tree to 118,300 seeds per mature tree (U.S. Forest Service, 

 Intermountain Forest and Range F.xp. Stn. 1937) . 



The reasons for the variability of seed crops are not fully known, but some obser- 

 vations and measurements have been made. In a northern Idaho study, pollen dispersal 

 was greatly reduced in years when rains fell during the pollination period (Turner 

 1956). The amount of seed killed by cone and seed insects can be extremely high in 

 some years (Keen 1958). A surprising number of birds and small mammals also consume 

 seed before it falls to the ground (Curtis 1948). Such losses are important in years 

 of light or medium seed production. Squirrels {Sciurus spp . ) , chipmunks (Eutamias 

 spp.)> and mice (Peromyscus spp.) are unquestionably responsible for the greatest 

 losses in seed, both from the tree and after dissemination. In western Montana and in 

 central Idaho, mice, chipmunks, or shrews [Sovex spp.) destroyed over 90 percent of 

 fallen ponderosa pine seed (Adams 1950; Foiles and Curtis 1965b; Schmidt and Shearer 

 1971) . In another study in western Montana squirrels not only destroyed close to 

 85 percent of the cone crop, but by the nature of their clipping, destroyed the current 

 year's seed, the 1-year-old conelets, and the flowering potential of the trees from 

 which cones were clipped (Squillace 1953; Adams 1955; Schmidt and Shearer 1971). It 

 was concluded from these studies that squirrels can harvest most of the seed crop in 

 light and medium seed years, thus minimizing the chances of adequate reproduction 

 establishment. Prevention of cone losses from standing trees by using metal bands to 

 repel squirrels and so protect a supply of genetically desirable seed proved successful 

 in western Montana (Tackle 1959). 



13 



