Elevation 



All elevations are given in relation to the average elevation of 

 the natural marsh at the particular site, lie Grande or Kerlavos. At 

 lie Grande the average elevation of the Juncus marsh on the southwest 

 side of the bridge was the reference datum. This average elevation is 

 tied to a white mark on the rock wall of the bridge for which 

 Mademoiselle Odile Guerin, who has worked on the lie Grande project, 

 has elevation tied to a national datum. The average elevation is also 

 tied to the concrete foundation of the bridge itself. At Kerlavos the 

 average elevation of the marsh is tied to a bench mark at an electric 

 station tower ca . 0.5 km from the study site. Based on relating water 

 levels at the two sites, the Juncus marsh at lie Grande is about 0.1 m 

 above the elevation of the natural marsh at Kerlavos. 



At lie Grande we planted Juncus , Puccinellia , Spartina and 

 Triglochin over a range of elevation from 0.8 m below to 0.3 m above 

 the average elevation of the natural Juncus marsh. Juncus transplants 

 did not survive at elevations below that of the natural Juncus marsh 

 and best survival occurred at 0.3 m above that of the natural Juncus 

 marsh. Puccinellia transplants did not survive at elevations of 0.7 m 

 below that of the natural Juncus marsh and survival was less than 10% 

 at elevations of 0.5 m below that of the natural Juncus marsh. The 

 best growth and survival of Puccinellia transplants was achieved in the 

 range of elevation between 0.1 m below and 0.3 m above that of the 

 natural Juncus marsh. Spartina transplants survived at the lowest 

 elevations of all species tested. Although Spartina transplants 

 survived at elevations of 0.8 m below that of the natural Juncus marsh, 

 growth was best at 0.3 m below that of the natural Juncus marsh. 

 Survival and growth of Triglochin was generally poor but its elevation 

 response was similar to that of Puccinellia with no survival at 

 elevations of 0.7 m below that of the natural Juncus marsh. 



At Kerlavos experimental plantings of Puccinellia and Triglochin 

 were established over a range of elevation from 0.5 m below to 0.1 m 

 below that of the natural marsh. The best survival and growth of these 

 Puccinellia transplants occurred at 0.2 m below that of the natural 

 marsh. Transplants at 0.4 m below the elevation of the natural marsh 

 did very poorly. Triglochin transplants responded in a similar manner. 



Halimione was planted at elevations from 0.1 m below to 0.3 m 

 above that of the natural marsh at lie Grande. Survival and growth of 

 these transplants were best at about 0.3 m above the elevation of the 

 natural marsh, but survival was good throughout the range of elevations 

 planted. At Kerlavos, Halimione was planted from 0.4 m below to 0.2 m 

 below the elevation of the natural marsh. Survival and growth was best 

 in the upper half of this elevation range. 



Plantings in General 



About 9,700 transplants have been planted at lie grande and about 

 1,800 others at Kerlavos over the period May 1979 through May 1981 

 (Table 2). Although half of these transplants were those of 



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