182 HARUYOSH] SAHO 



NATIVE JAPANESE WHITE PINES 



PINUS PENTAPHYLLA MA\ k (NOkTHEkN JAPANESE TAXON OF P. PARVIFLORA SIEB. § 

 ZUCC.) 



The climate over the range of P. pentaphylla is cool. This species 

 is distributed in areas where the annual average temperature is 7 to 14. 5 C 

 (45 to 58°F) from north to south, respectively. At the Hidaka Mountains 

 in Hokkaido 350 to 500 m above sea level, almost at the northern limit 

 of the natural distribution, the average minimum temperature is -14.5 to 

 -15°C (7 to 5°F). At Urakawa, Hokkaido, this species grows near the sea 

 coast, 50 m above sea level, on steep hills facing west. The average 

 minimum temperature during the year is -6.9°C (about 20°F) recorded in 

 January. At the highest place of the natural distribution on Mt . Fuji, 

 Honshu (2500 m elevation) , the average minimum temperature is about 

 -14.7°C (6°F) . Here the recorded minimum temperature was about -28°C 

 (-18°F) observed in 1936. This is close to the -15°C average minimum 

 observed at the Hidaka Mountains. 



The southern limit of the natural distribution is at Kita National 

 Forest, Shizuoka Prefecture, Honshu (700 to 1000 m elevation), where the 

 average maximum temperature is 25.9 to 30.3°C (78 to 87°F) . Therefore, 

 P. pentaphylla can grow where average maximum summer temperatures reach 

 about 30.0°C. 



The average annual precipitation of the area of the natural distribu- 

 tion of this species is 1000 to 2000 mm ( 39 to 79 inches) , in some cases 

 2500 to 3000 mm. Dividing the annual precipitation between summer rain 

 and winter rain or snow discloses no relationship of summer or winter 

 precipitation to the distribution of P. pentaphylla. 



Soils within the range of P. pentaphylla are derived from andesites, 

 shales, clay-stones, sand-stones, and tuf fes . This species usually grows 

 on the moderately moist soil, but it is rather resistant to drought and 

 may grow in small pure stands on the ridge-top or on other fairly dry, 

 rocky places like the slopes near the ridge-tops. When P. pentaphylla 

 grows on a windy site in mixture with P. pumila, it assumes a windblown, 

 snow-flattened shape quite similar to P. pumila. 



Usually P. pentaphylla is considered an intolerant species but its 

 seedlings grow better under the diffused light of the forest than do 

 those of Pinus densiflora Sieb. § Zucc. P. densiflora usually grows in 

 full sunlight in forest openings. When P. pentaphylla forests are clear- 

 cut, no natural reproduction of the species becomes established in the 

 resulting openings. 



Extensive natural forests of the species are now limited, although 

 scattered remnant stands remain in many places. Three samples are shown 

 below. 



(I) 2 Hakodate Forest A, Hokkaido, is located 320 ... above sea level, 

 on a 5 to 20° slope on sandy soil. It is 50 years old. The average 

 height is 15 m, the average diameter is 18.6 cm (range 6 to 36 cm). The 

 density is 915 trees/ha (2.5 acres), and volume is 196 m 3 /ha. The annual 

 growth is 3.9 m 3 /ha. 



2 Numbers in parentheses refer to forest and plantation locations 

 on Figure 1 and Table 1. 



