Salt-iaarsh plants did not recover from overwash burial that exceeded 45 

 centimeters. Six salt-marsh species were present in 1977; four drift-line 

 species were present in 1978. Postoverwash vegetation was found in scattered 

 storm-generated drift piles and bay-side drift lines. The similarity index 

 (0.0) emphasized the complete change in plant community composition. 



(d) Comparison 8 . Site l-F-78 was subdivided in order to 

 analyze a salt-marsh community that received greater than 34 centimeters of 

 overwash sand burial. Quadrats at site 1 fan that received greater than 

 34 centimenters of sand and had not eroded were analyzed. A map of the loca- 

 tion of these 261 quadrats appears in Figure 38. Vegetation data for these 

 quadrats were compiled for iy77 and 197a (Tables 23 and 24). The 1977 area 

 was dominated by Spar'tina patens (l.V. « 242.9) with Spartina altevniflora 

 (l.V. = 28.7) and Salicofnia virginica (l.V. = 13.1) as subdominants. 



Mean elevation in the area was raised 72 centimeters. As in comparisons 

 5, 6, and 7, topographic relief was increased from 1977 (o » 0.19 taster) to 

 1978 (o = 0.29 meter). Plants did not recover from overwash burial in excess 

 of 34 centimeters. Six salt-marsh species were present in the sampled quad- 

 rats in 1977, while three drift-line species were present in 1978. Postover- 

 wash vegetation was found principally in bay-side drift lines deposited during 

 the late March spring tides. As in comparison 7, the similarity index was 

 0.0, stressing a complete change in plant community composition in areas 

 receiving deep (>34 centimeters) deposits of sand. 



(e) Comparison 9. (juadrats sampled at site l-F-w-77 were com- 

 pared with quadrats from site " 1-F-ru- 7 7 to analyze the effect of deep overwash 

 burial on a salt marsh after b years (Tables 5 and 7). The mean elevation of 

 the washover area was 41 centimeters higher than the surrounding marsh. Salt- 

 marsh vegetation did not recover from the initial washover deposit. Only one 

 species, Sparf-ina patent, was present at the salt marsh, and also on the wash- 

 over fan. Aeolian deflation of the surface created a low area where seedlings 

 of Spar'tina patens because established. Kruskal-Wallis tests on cover and 

 density of Spar'tina patens and cover for bare sand showed that there were 

 significant differences between 1977 and 1978 (P < 0.01). The high similarity 

 index (42.2) comparing the two areas reflects the growth habit and elevation 

 r&nge of Spa^tina patena and the sparseness of vegetation on recent washovers. 



(f) Comparison 10 . The 234 quadrats saaspled at site 2 in 1977 

 were compared with the sasee quadrats resaapied in 1378 to illustrate the 

 effect ot continual overwash o.i a mixed high or low aarsh community. Site 2 

 supported a mixed high or low marsh coarauntty in 1977 that experienced between 

 20 and 50 centimeters of overwash deposition during the February atona. The 

 area, however, continued to overwash during spring tides until July. Plants 

 did not recover from overwash burial, although at tiaes during the growing 

 season dead biomass frois the 1977 vegetation was exposed. Drift-tine vege- 

 tation was not present in the area because drift aater'at was not deposited on 

 the washover surface. Drift-line vegetation could not have withstood salt- 

 water inundation during the growing season, even if it had been present.. 



(4) Ordination of Data. In Figure 39, wo distinct groupings aie 

 evident in the ordination of data collected on Nauset Spit-Easthara in 1977 and 

 1978: salt-marsh communities (lower right) and dune coisaunities (upper left). 

 Marshes affected by shallow overwash burial (site l-F-p-77 and site l-F-p-78) 



85 



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