The three other major dune species (Solidago senrpevvivens, Avtemiuia 

 stelleviana, and Lathyvus japonicus) on Nauset Splt-Eastham are also able to 

 expand both vertically and laterally by rhizome extension, although not to the 

 same degree as Ammophila bveoiligulata. Individual plants of Solidago sempev- 

 virens that recovered from burial (of about 40 centimeters) were as much as 40 

 centimeters larger in diameter the year after overwash. Artemisia, stelleviana 

 plants expanded less rapidly, approximately 10 to 20 centimeters per year. 

 Lathyvus japonicus can freely expand by rhizome extension; plants in the dunes 

 may be several meters apart and connected by rhizomes. During the 1978 and 

 1979 seasons, Lathyvus japonicus did not, however, appear to expand into 

 uncolonized substrate on Nauset Spit -East ham. 



(2) Salt Marsh . Both Spavtina patens and Spavtina altevniflova 

 commonly colonize new substrate by rhizome extension. Redfield (1972), 

 studying the development of the salt marsh behind Sandy Neck in Barnstable, 

 Massachusetts, over a 12-year period, calculated that Spavtina altevniflova 

 would have to colonize new substrate at a rate of 1.3 meters per year to 

 produce the salt-marsh enlargement evident in dated peat deposits. He rea- 

 soned that Spavtina altevniflova rhizome extension alone was not sufficient to 

 account for this rate of expansion. Colonization by new propagules (either 

 seeds or fragment regeneration) would be necessary for such rapid salt-marsh 

 establishment. Over hundreds of year.;, new marshes formed at the leading edge 

 of the sandflats and were eroded several times before a permanent, continuous 

 marsh was formed. 



On Nauset Spit-Eastham, there were no salt-marsh plants unaffected by 

 burial contiguous to washovers in 1978. Spavtina patens and Spavtina altevni- 

 flova plants that were able to recover did so by vertical rhizome ext3t>t>ion 

 through washover deposits. These plants did not expand laterally the first 

 year. 



Stands of Spavtina patens that had recovered in 1978 enlarged by rhiacnie 

 extension the following year. There was no evidence from quadrat data that 

 Spavtina altevniflova had expanded by rhizome extension. Vegetation maps of 

 site 1 in 1977, 1978, and 1979 indicated that Spavtina altevniflova popula- 

 tions expanded 1 meter into new substrate at lower elevations. Spavtina 

 patens patches expanded vigorously on all fronts, extending as far as 50 

 centimeters per year from the 1978 plants. Elevation information indicated 

 that Spavtina patens was present in quadrats at higher elevations in 1979 than 

 In 1978 or 1977. In 1979, 34 quadrats, which were not vegetated in 1978, were 

 colonized by Spavtina patens through rhizome extension. Mean elevation for 

 these quadrats wss 8 centimeters higher than the mean of recovering quadrats; 

 these higher elevations were within the range of Ammophila bveviligulata. 



d. Seed and Fragment Regeneration . The depth of 1978 washover deposition 

 on Nauset Spit-Eastham generally exceeded levels from which marsh vegetation 

 could recover. Sand dunes were generally eroded by storm surges, except where 

 low or initially building. Most washovers on Nauset Spit-Eastham were also 

 too far removed from remnant dunes or recovering salt marshes to be affected 

 by rhizome extension. The most effective means of colonizing washovers is by 

 the establishment of new vegetation. In all, within sampled sites, 89 quad- 

 rats (of a total of 2,567 quadrats) were populated with new plants in 1978. 

 In 1979, following a winter with exceptionally high tides, 298 quadrats had 

 new plants. 



125 



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