EXPERIMENT STATION BULLETINS. 405 



placed two feet or less apart at the edge of the belt, another row planted 

 in the same way is set three to four feet inside of the first row. In ex- 

 ceptionally exposed blows it often becomes necessary to set one or even 

 two more rows of willows, placing them closer together and thus cover- 

 ing the first ten feet of the belt. This forms the facing or front. Be- 

 hind the willow and still within the dead cover area alternating trees of 

 Carolina poplar, spruce or pine should be set in rows four to five feet 

 apart. First a one-year Carolina poplar and four feet from it an ever- 

 green, then a Carolina poplar, then an evergreen, etc. These rows, 

 alternately poplar and conifer, are best set four by four feet on areas 

 exposed to heavy wind. Two objects are attained in the alternate plant- 

 ing of poplar and conifers. First, a good growth and high per cent of 

 living trees is assured by the use of Carolina poplar, since ninety-five 

 per cent of the trees of this species should survive. The rapid growth 

 for the first ten to fifteen years assures a quick shelter against the sand 

 carrying wind. Second, the poplars are short lived and their foliage does 

 not monopolize the entire crown area, and further, they recover readily 

 from the wind and storm injury to which the}^ are subjected. When 

 the poplar has stood the brunt of ice and snow storms for a dozen or 

 more years it should be removed to furnish space for the permanent 

 trees. Conifers make the best permanent forest crop on exposed sands 

 because they form a dense screen through which the wind cannot pass 

 and cast a dense shade which is conducive to the accumulation of humus 

 forming litter, preventing the excessive drying out of the sand fioor 

 which often occurs during the dormant season when covered by deciduous 

 trees only. They are also quite free from insect pests and produce 

 higher returns from the lumber than do the hardwoods. Conifers do 

 not succeed when planted alone on the sand dunes, however, because, 

 owing to their slower growth at the start, they are more easily blown 

 out or buried during the early years after planting, and they present 

 a heavy evergreen top before the roots are sufficiently established to with- 

 stand the pulling, rocking action of the wind, which loosens them to 

 such an extent that they are barely able to keep alive. They also suffer 

 during the first and second seasons from excessive transpiration when 

 standing unprotected. 



An artificial or ''dead" cover should be established in bad cases. This 

 consists of any convenient material being placed on the land at the point 

 of wind attack. (Fig. 6.) Cornstalks, rotted marsh hay, brush, poles, 

 old lumber scrap, rotted saw dust, cut weeds, etc., may be used, or 

 sometimes short stakes, barrel staves, etc., may be driven into the sand 

 at close intervals. The sole object of this cover is the obstacle furnished 

 to the clear action of the wind. This material should be placed uni- 

 formly over the belt or strip extending along the edge of the blow or 

 along the shore of the lake, and a few feet above the high water mark of 

 winter storms and ice. The width covered depends entirely upon the 

 size of the dune and the resources available in any one year for the 

 work. The belt may be covered for a wadth not less than a rod and 

 preferablv at least three or more rods the first year. The covering of 

 this belt "with dead material constitutes the last operation and is known 

 as the dead cover. 



Subsequent work under this method should be carried on by the estab- 

 lishment of successive belts parallel to the first. An interval of one 



