Multiple-linear regression was used to determine if there wer<» an inter- 

 action between initial (1977) cover or density values and burial depth that 

 could lead to a significant prediction of final cover value. A significant 

 relationship was not determined. 



Ammophila breviligulata is able to recover from 59 centimeters of overwash 

 sand burial. Plant recovery shows no differential response to burial depth. 

 The physiological Limit of Ammophila breviligulata for recovering from burial 

 was probably not reached in this field study. Initial cover reflects original 

 aboveground biomass and often nay be used to predict final cover. Initial 

 density reflects the number of tillers that can grow through sand deposition. 

 The ability of a plant to grow through a sand deposit must be determined by 

 the amount of stored material (carbohydrates and nitrogenous compounds) that 

 can be remobilized for the large burst of growth needed to reach the new sand 

 surface. Plants that produce high aboveground biomass, measured by the cover 

 figure, are not necessarily those plants with best below-ground biomass and 

 therefore storage capacity. High aboveground biomass may be produced at the 

 expense of stored material, but may also reflect a greater ability to produce 

 photosynthate and therefore greater storage ability. Density data indicate 

 the number of actively dividing apexes present that can grow through sand 

 deposition. While cover and density data for Ammophila breviligulata were 

 highly correlated (1977, r = 0.548; 1973, r = 0.522), density is a much better 

 predictor of recovery ability (cover, r = 0.245; density, r = 0.502) than 

 cover. 



Overwash activity is important in dune-building processes, at least during 

 the early stages of development (Schwartz, 1975). In some areas, overwash 

 swashes will climb low dunes without causing major erosion. Energy will be 

 dissipated and any entrained sediment will settle out on the low dune area, 

 resulting in sand deposition and dune growth. Differential deflation of wash- 

 overs also leads to the formation of dunes. Hosier (1973) ana Godfrey and 

 Godfrey (1974) cite the role of washover sand deposition in the formation of 

 low, Vniola dunes in North Carolina. Some overwash deposits contain Uniola 

 paniculata (sea oats) fragments that regenerate, grow, and trap sand. The 

 combined action of sand accretion in vegetated areas and unvegetated washover 

 fan deflation led to the formation of small dunes. Dune size is limited by 

 the amount of available sand, which is reduced by (a) the formation of a heavy 

 lag layer of shell and pebble, and (b) the development of dense vegetative 

 cover on the washover fan from recovering or colonizing plants. 



Limited areas of the touset Spit-Eastham dune line were buried by washover 

 sand. Ammophila breviligulata growing on high, well-developed dunes may be 

 either unaffected by overwash or eroded. Ammophila breviligulata does not 

 grow in low-lying areas near the ocean or bay beach since it cannot withstand 

 seawater flooding during the growing season. It also does not grow in low- 

 lying areas within the dune field since the freshwater table is very near the 

 sand surface, and Ammophila breviligulata roots and rhizomes cannot tolerate 

 waterlogging (Jones and Etherington, 1971). Dunes that are affected by over- 

 wash burial and can recover are, therefore, restricted by storm erosion and 

 the natural elevation range of Ammophila breviligulata. A transect surveyed 

 in the summer of 1977 and in February, June, and August 1978 is presented with 

 quadrat information in Figure 44. Areas of dense Ammophila breviligulata 

 recovered best from overwash burial; areas that did not recover from burial o^ 

 were unvegetated in 1977 were deflated by the wind. A more generalized model 

 of the overwash role in dune building on northeastern barrier beaches appears 

 in Figure 45. 



95 



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