196 SEEDING AND PLANTING 



the foredune. The foredune is constructed at a distance of from 

 30 to 100 yards from the shore. It must be high enough to arrest 

 the forward movement of the sand. Its efficiency results from the 

 fact that, although the wind will move sand along level or sloping 

 ground, it will not lift it above a certain height. 



The usual practice in the artificial formation of a foredune is to 

 break the wind by erecting a suitable fence parallel to and at the 

 proper distance from the coast. The forward movement of the 

 sand is arrested, part being deposited in front of the fence while 

 the remainder passes through the openings and comes to rest in 

 the comparatively quiet area beyond. As soon as the fence is 

 nearly covered by the accumulated sand it is removed and re- 

 erected on the top of the developing dune. This process is con- 

 tinued un^il the sand, continually washed up by the waves, is no 

 longer carried over the crest of the dune. As the foredune de- 

 velops it often becomes necessary to erect an additional fence of 

 brush or other material on its leeward side. The aim should be to 

 force the dune to develop a moderate slope on both faces as this 

 is essential to its permanency. As soon as the dune has been 

 raised to the proper height attention can be given to fixing the 

 sand temporarily on the area behind it. As a rule, the foredune 

 must be from 25 to 35 feet in height. The slope to the windward 

 is usually from 4 to 14 and to the leeward from 20 to 30. After 

 the dune has reached the proper size it must be given close atten- 

 tion in order to keep it in repair. This is accomplished by plant- 

 ing sand-binding plants, covering the surface with litter which 

 prevents the wind from reaching it, or by constructing a network 

 of brush fences over it. 



Because of the salt spray and high wind velocity the foredune 

 cannot usually be planted with trees. In order to keep it in place 

 permanently the best results are attained by planting various 

 grasses and sedges which develop long, heavy rootstocks. Al- 

 though many species have been used for this purpose, the common 

 beach grass (Ammophila arenaria) has proved most effective in 

 this country. This grass grows naturally in most of the dune 

 regions of both this country and Europe. It spreads rapidly by 

 means of creeping underground stems or rhizomes. Beach grass 

 cannot be established by seeding. The heavy rootstocks or un- 

 derground stems are gathered either in the fall or in the early 

 spring and reset immediately. Plants should be 2 years old 



