EXPERIMENTS ON THE PRESERVATION OF PRINCIPAL 

 FOREST TREE SEEDS 



By Dr. HOMI SHIRASAWA, Forest Expert and MITSUO KOYAMA, Assistant Forest Expert 



Few forest trees produce seeds every year, most of them producing 

 every other year. The harvest of seeds and the interval between seed 

 bearing years vary with the tree species while the climatic condition of 

 the year and particularly the temperature, moisture and wind at the time 

 of inflorescene and fructification greatly affect the harvest of tree seeds. 



Of the six principal trees in this country that are used in replantation, 

 Akamatsu (Pinus densi flora) and Kuromatsu (Pinus Thunbergii) only 

 produce seeds every year; Sugi (Cryptomeria japonica), Hinoki (Chamce- 

 cyparis obtusa) and Kusu (Cinnamomum Camphora), generally every other 

 year while Karamatsu (Larix leptolepis) produces only once in every 4 

 to 7 years, and the other year they bear no seed at all or only those of 

 a less vigorous nature. The germinating power of seeds varies with the 

 tree species. Thus, the seeds of Akamatsu and Kuromatsu keep their 

 germinating power for 2 or 3 years while those of Sugi, Hinoki, Kara- 

 matsu and Kusu can not retain this power even for one year losing it in 

 the summer of the next year. 



In view of this fact, it is only natural to suppose that the price of 

 seeds rises enormously in the year of a poor crop. Consequently seeds of 

 poor quality are frequently offered in the market to meet the demand of 

 the seeds. 



The regular supply of sound seeds and strong seedlings at reasonable 

 prices is an important factor in successfully carrying out the replanta- 

 tion of forest land. If these supplies can be obtained, sylvicultural 

 works extending over a term of years can be safely undertaken. Seeds 

 of Sugi and Hinoki are procurable everywhere as the trees are common 

 throughout the country. Any shortage in these seeds in one locality can 

 well be covered by drawing upon the surplus stock in others. The use of 

 seeds may likewise be avoided by using plants obtained from cuttings or 

 layers. It is quite otherwise with a tree such as the Karamatsu which 

 bears seeds only once for every 4 to 7 years and the growth of which is 



