8 



Fig-. 4. After 15 years, the remaining rows, 1, 2 and 3, are cut out and re- 

 planted. 



6 



Fig. 5. After 20 years, the last rows, 1, 2 and 3, are 5 years old and 

 are 20 years old. The regeneration of the shelterbelt is completed. 



and 9, 



Third Step: After another five-year period has elapsed, cut out 

 rows 4 and 5 and replant them. This leaves but three rows of the 

 old trees for giving protection. By this time, however, if broadleaf 

 trees or fast-growing evergreens have been used for planting, the 

 trees in rows 8 and 9 should be large enough to give good wind 

 protection themselves, thus reinforcing the old rows remaining. 



Fourth Step: After the third five-year period, cut out the re- 

 maining three rows of old trees and replant. If the plantings are 

 successful, the regeneration is completed. 



USE OF THE METHOD FOR DIFFERENT SHELTERBELTS 



The method of regeneration from one side is adaptable to groves 

 of any species, since the successive cuttings progress in a way to 

 give an abundance of light to the new growth, no matter what the 

 original grove is composed of. 



Cotton wood: The cottonwopd matures at an age of 35 to 40 years. 

 It requires an abundance of light for growth and, as a result, stands 

 of this species are relatively open. Many of these shelterbelts in the 

 state are 35 to 40 years old and, under usual conditions, will last 

 long enough for the application of this system of regeneration. 



There will be difficulty in using the old trees for lumber, since it 

 usually would not be profitable to bring in a portable sawmill every 



