planting on Ocracoke Island, North Caro- 

 lina, included 50% American beachgrass 

 and 50% sea oats. After 10 yr sea oats 

 still dominate much of the zone where 

 the sand is no longer active or accumu- 

 lating. In the active sand zone where 

 it is accumulating on the ocean side of 

 the dune, American beachgrass dominates. 

 This is a characteristic response of 

 American beachgrass; it does best where 

 fresh sand is accumulating and it will 

 grow toward the sand supply on the beach 

 (berm) at a rate of up to 3 m (10 ft) 

 per year. The rhizome network of Ameri- 

 can beachgrass has much greater poten- 

 tial for spread than does that of sea 

 oats. Even though American beachgrass 

 has some problems (e.g., disease, insect 

 pests) along our coastline, it also has 

 some definite advantages. In mixed spe- 

 cies plantings, beachgrass acts as a 

 nurse crop, builds the dune, and has the 

 capacity to alter the dune's configura- 

 tion by growing toward the sand supply. 

 Eventually beachgrass will surrender 

 dominance to other plants which results 

 in a natural vegetative composition 

 which is what we wanted in the first 

 place. 



In many cases in the past, man- 

 initiated dunes have been placed too 

 close to the ocean. Sandy shorelines 

 advance and retreat; initial placement 

 of a dune planting must allow for this 

 movement. Because the overall trend 

 along much of the Atlantic coast is that 

 of a receding shoreline, dunes should be 

 built at least 100 m (33 ft) from the 

 high tide line. 



In another mixed-species experiment 

 near Drum Inlet, North Carolina, we put 

 in a 0.6-m (2-ft) sand fence to accumu- 

 late a small ridge of sand prior to 

 planting. We did this to gain a little 

 elevation on a very exposed beach. The 

 planting included sections of American 

 beachgrass, sea oats, and bitter pani- 

 cum, alone and in combination. By the 

 third growing season, the American 

 beachgrass section had accumulated more 

 sand and moved further toward the ocean 

 than either the bitter panicum or the 

 sea oat sections. A section of the bit- 

 ter panicum and sea oats together did 

 almost as well as the section of Ameri- 

 can beachgrass alone; however, the mix- 

 ture did not migrate as far toward the 



ocean. The mixture of American beach- 

 grass and bitter panicum was no more 

 effective than that of American beach- 

 grass alone. American beachgrass is 

 still superior to anything else that we 

 have tried. When we planted a three-way 

 mixture (American beachgrass, sea oats, 

 and bitter panicum), a dune was created 

 that was a little steeper on both the 

 front and back slopes than dunes created 

 by American beachgrass alone. For all 

 practical purposes, however, sand accum- 

 ulation was the same. Experiments 

 indicate that it is best to use mixtures 

 of grasses to stabilize and build dunes 

 along our coastline, even though Ameri- 

 can beachgrass alone might accumulate 

 sand at a faster rate. The mixture is 

 best because American beachgrass is 

 subject to disease and insect problems 

 which become evident the second growing 

 season following planting. 



Coastal foredunes are the first 

 line of defense. They are dominated 

 primarily by perennial grasses with a 

 scattering of other plants. Woody 

 plants do not appear to be the answer to 

 problems involved with dune building and 

 dune stabilization with a situation of 

 rising sea level and a retreating shore- 

 line. Shrubs grow on the back side of 

 the foredune and in other protected 

 areas. They cannot survive on the top 

 and ocean slope of the foredune because 

 they cannot withstand the high concen- 

 trations of wind-borne salt spray. Be- 

 hind the foredunes there may be inner 

 dune areas, swales, or sand flats, where 

 grasses and other herbaceous vegetation 

 still dominate, but where shrubs become 

 more prominent. Still further inland, a 

 zone of woody vegetation develops. This 

 woody vegetation may be a low-growing 

 maritime shrub thicket or it may be a 

 maritime forest. It is composed of wax 

 myrtle ( Kyrica cerifera ), yaupon ( Ilex 

 vomitoria ), red cedar ( Juniperus virgin- 

 iana ), five oak ( Quercus virginiana ), 

 and laurel oak ( Quercus lauri folia ) to- 

 gether with greenbriar ( Smil"ax spp.), 

 wild grapes ( Vitis spp.) and poison ivy 

 ( Rhus radicansj! Where you find trees 

 or shrubs next to the ocean, it is prob- 

 able that the ocean has cut to them, not 

 that the trees and shrubs have grown 

 toward the ocean. 



In summary, coastal foredunes are 



61 



