■■')' 



b. M ethodology . The 2,567 quadrats sampled at the three research sites 

 on Nauset Spit-Eastham in 1977 were resampled in 1978 after the February 1978 

 northeaster. Vegetation and elevation data were analyzed using computer 

 programs for simple and multiple linear regression and t-tests (Dixon, 1977). 

 Since most data were not normally distributed about a mean, Kendall's correla- 

 tion coefficients were calculated for all regression analyses and fed into a 

 program designed to use reduced data (Dixon, 1977). The Kruskal-Wallis test 

 and the Mann-Whitney U-test were used to compare treatment means for nonpara- 

 metrtc data, whenever appropriate. An arcsin transformation was used fcr 

 species cover data, which were expressed as percentages. 



c. Analysis of Data . 



( 1 ) Dune Species . 



(a) A mrnop h i l a bre vil igu la ba . Large sections of the dune at site 

 3, not eroded during the February storm, were buried by up to 98 centimeters 

 of washover sand. A total of IG8 quadrats sampled in 1977 with Ammophila 

 breviligulata were buried by between 5 and 98 centimeters of sand; 68 quadrats 

 (63 percent) were recovered from burial (Table 25). Some of the Ammophila 

 breviligulata that did not recover may have been eroded during the storm or 

 may have been displaced slightly outside the quadrat. 



There is no significant linear relationship between the 1978 (poststorra) 

 cover or density data for Ammophila breviligulata and the depth that plants 

 were buried using quadrats containing Ammophila breviligulata in 1977 (108 

 cases) or quadrats that contained recovering Ammophila breviligulata in 1978 

 (68 cases). The data set was divided into the 1977 quadrats with Ammophila 

 breviligulata that recovered and those that failed to recover. Using the 

 Kruskal-Wallis test (and the Mann-Whitney U-test) no significant differences 

 were determined for burial depth between the two data sets (Fig. 41). 

 .Although 40 quadrats with Ammophila breviligulata did not recover from over- 

 wash burial, burial depth was probably not a limitation to recovery ability. 

 Plants buried by 60 centimeters of sand recovered as well as plants buried by 

 smaller amounts of sand. 



Failed to recover from over 

 burial. x * 33.4 ca (40 ca 



Recovered from overvash burial. 

 x - 30.2 cm (68 cases) 



Kruskal-Wallis test results: The rank mean 

 for quadrats In which plants did not recover 

 from burial does not differ significantly 

 from the rank mean for quadrats in which 

 plants did recover (P > 0.05). 



Figure 41. Comparison of burial depths for quadrats of Ammophila 

 breviligulata that recovered and failed to recover. 



93 



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