DUNE STABILIZATION WITH PANICUM AMARUM ALONG THE 

 THE NORTH CAROLINA COAST 



by 



E.D. Seneca, W.W. Woodhouse, Jv., 

 and S.^ . Broome 



I. INTRODUCTION 



The perennial coastal dune grass Paniaim amariffn Ell. (bitter 

 panicum) (Fig- 1) is distributed on foredunes in a discontinuous manner 

 from New England to Florida, and around the gulf to Texas. The 

 taxonomy, distribution, and habitat preferences of bitter panicum have 

 been described in a study by Palmer (1975) . She indicated that this 

 grass is a sterile form of Paniaum amarulum Hitchc. § Chase (shoredune 

 panicum), and is well adapted to the foredune habitat. The shoot and 

 rhizome systems have the potential to produce new shoots and roots at 

 the respective nodes as described by Dahl, et al. (1974). The growing 

 season (aboveground growth) along the North Carolina coast is from May 

 through October, which is about 2 to 3 months less at this latitude than 

 that of Ammophila brevil-igulata Fern. (American beachgrass) . However, 

 unlike American beachgrass which is a temporary stabilizer and often 

 loses dominance within 5 to 10 years along the southeastern coasts, 

 bitter panicum forms a part of the permanent cover along with Uniola 

 panioulata L. (sea oats). 



There is no universal agreement among dune researchers as to the 

 reason for the discontinuous distribution and, until recently, for the 

 relative sparsity of bitter panicum along much of the coast. Some 

 researchers believe that this grass was grazed out by free-roving 

 livestock, while others feel that certain environmental factors are 

 responsible. Dahl, et al . (1974) noted that it is preferred by cattle 

 to several other dune grasses on the Texas coast. Whatever the 

 limiting factors were in the past, within recent years established 

 stands of bitter panicum on the North Carolina coast have spread and new 

 areas are being colonized. 



Earlier dune building and stabilization studies along the North 

 Carolina coast have concentrated on American beachgrass (Woodhouse and 

 Hanes, 1967) and sea oats (Woodhouse, Seneca, and Cooper, 1968). 

 Although American beachgrass is a good dune builder at this latitude, it 

 is attacked by a scale insect, Eviocooous aarolinae Williams (Campbell 

 and Fuzy, 1972), is susceptible to the mushroom- forming fungus, 

 Marasmius sp. (Lucas, et al., 1971), and appears less drought tolerant 

 than sea oats. A controlled environment study with seedlings grown from 

 seed collected along the Atlantic and gulf coasts suggested that 

 temperature is a major factor responsible for the observed replacement 

 of American beachgrass by sea oats south of the Virginia-North Carolina 

 line (Seneca, 1972). A recent study on the Texas coast established that 

 bitter panicum and sea oats were the two best adapted plants tested for 



