and rolling of leaves, followed by chlorosis on the outer older leaves 

 with leaf tips becoming yellowish^ Necrosis later proceeded from the 

 tips downward, affecting the newest leaves last, Ammophila 

 breviligulata and Uo pan-icuZata grew moderately well in salinities 

 up to 1 percent while P. amaTulum showed no signs of salinity stress 

 until subjected to 2-percent NaCl. Seedlings of So patens showed 

 salinity stress only at the 4-percent level. It was the only species 

 to actively secrete what was thought to be NaCl from its leaves. All 

 species lived for at least 10 days when exposed to 4-percent NaCl. 



bo Nutrients. Willis, et al . (1959) reported a low level of 

 nitrogen in the sandy soil of the coastal dune system of Braunton 

 Burrows, North Devon, England. After further studies Willis (1963) 

 attributed the sparse vegetation on this dune system to low levels of 

 nitrogen and phosphorus, which appeared to be due to the high 

 leachability of the coarse sandy soils. 



Wave deposition of organic detritus has been suggested as the 

 source of nutrients for the lower beach (Ranwell, 1972), Wagner (1964) 

 cited the freshly deposited beach sands as a source of nitrogen, while 

 Morris, et al . (1974) suggested ocean spray-carried neuston as a 

 possible source. 



Hassouna and Warling (1964) isolated bacteria from the root soil 

 and roots of A, arenaria and found that Asotobaotov , a nitrogen-fixing 

 bacterium, constituted a large proportion of these organisms. Their 

 studies indicated that the root surface micro-organisms in the dune 

 sand could stimulate significantly higher plant growth in the absence 

 of added nitrogen when root exudates (a carbon source) was added. They 

 concluded, "there seems little doubt that the fixation of atmospheric 

 nitrogen is an important factor in the nutrition of A. arenari-a^^^ 



Stewart (1967) showed that nitrogen fixed by blue-green algae in 

 soil was utilized by higher plants. Most fixed nitrogen remained in 

 the first centimeter of the soil unless leached. 



Morris, et al . (1974) have shown that root nodules on M, 

 pensylvaniaa contain a bacterial endophyte. They found large numbers 

 of nodules on main and adventitious roots. Nitrogen fixation was 

 vigorous. They concluded that the success of M. pensylvaniaa as an 

 early successional species on dunes and other impoverished soils was 

 due, at least in part, to the nitrogen-fixing capacity of their 

 nodular bacteria. 



Gorham (1958) found the mobile dunes in Norfolk, England, richer 

 in soluble calcium, nitrate and silica and the stable phase dunes 

 richer in soluble carbon and phosphate due to humus accumulation. 

 The oldest stabilized dunes were richest in potassium, sulfate, 

 and phosphate. Magnesium, sodium, and chlorine were always 

 highest in the embryo dunes due to salt spray. Potassium was least 

 in the embryo dunes, and greatest in the stabilized dunes. Calcium 



