Fig. 13. After 10 years the newly planted trees are large enough to permit the 

 removal of the remaining old trees, row 1, without injury. This row should be 

 planted the same year. 



Fig. 14. After 15 years the regenerated shelterbelt should give good protection. 



be composed of different species, care must be exercised in the selec- 

 tion of combinations, to prevent overtopping and killing the slower 

 growing or intolerant trees. 



This system should be applied to cottonwood, soft maple, willow 

 and boxelder shelterbelts which are too old or degenerate to be satis- 

 factorily regenerated by one of the slower methods, or where the 

 protective feature of the grove is not of great importance. 



SPECIES USED IN PLANTING 



When one species is to be used throughout the entire shelter- 

 belt, any tree which is suited to the climatic, soil and moisture condi- 

 tions of the locality may be used. The following is a partial list of 

 trees which might be used: Cottonwood, hardy catalpa, soft maple, 

 hard maple, black walnut, red oak, white pine, red pine, Austrian pine, 

 western yellow pine, Norway spruce, European larch, red cedar, white 

 cedar. 



COMBINATIONS FOR REPLANTING 



Combination No. 1. 



The Norway spruce, white cedar or red cedar might be alternated 

 with the cottonwood or other thin-crowned, fast-growing species. 

 These evergreens are tolerant of shade and would make a fair growth 

 under the light shade of trees such as the cottonwood. 



