saltwater at 2° to 3° Centigrade over winter. Seeding should be done in 

 April (in North Carolina) at the rate of 100 viable seed per square meter 

 by incorporating the seed in the upper 1 to 3 centimeters of the substrate. 

 Seedlings grow rapidly during the first growing season and under favorable 

 conditions usually produce a better cover than transplants during the same 

 period. 



Selecting a site within the proper elevation zone for growth of S. 

 alterniflora is critical. The vertical zonation of the grass is deter- 

 mined by interaction of environmental factors (the most important being 

 tide range) peculiar to each location. The upper and lower limits of 

 growth for a potential planting site can usually be found by determining 

 the upper and lower limits of growth of nearby natural stands. Stands 

 will resist competition from invading plants in areas of higher salinity 

 (>25 parts per thousand) and longer periods of inundation (>8 hours) . 

 The substrate of a planting site is important in its ability to support 

 equipment, its nutrient supplying capacity, and its effect on salt 

 buildup. 



Development of transplanted or seeded areas is rapid. After two 

 growing seasons there is little difference in appearance and primary 

 productivity of the vegetation between artificially propagated marshes 

 and long-established natural marshes. The length of time required for 

 a new marsh to achieve a fully functional biological role is unknown. 



The relationship of mineral nutrition to growth of S. alterniflora 

 was determined by sampling plants and soils in natural stands and by 

 applying fertilizers to natural stands, transplants, and seedlings. 

 Results of the natural marsh sampling and subsequent regression analysis, 

 indicated that tissue concentrations of several nutrients and several 

 soil properties were related to productivity of S. alterniflora. Variables 

 negatively associated with yield were salinity of the soil solution, 

 manganese concentrations in the plants and soil and sulfur concentrations 

 in the plants. Variables positively associated with yield include 

 phosphorus concentrations in the plant tissue and in the soil. 



Results of fertilizer experiments in natural stands indicate that the 

 productivity of some salt marshes is limited by the supply of nutrients. 

 The standing crop of aboveground growth of S. alterniflora growing on a 

 sandy substrate was increased significantly by additions of nitrogen 

 alone and increased about threefold when phosphorus was also applied. 

 In a marsh developed on finer-textured sediments, nitrogen fertilizer 

 doubled the standing crop of short S. alterniflora, but there was no 

 response to phosphorus. Tall S. alterniflora did not respond to either 

 nitrogen or phosphorus. Nitrogen and phosphorus fertilizers enhance 

 growth of transplants and seedlings artificially established on dredge 

 spoil. These findings suggest that salt marshes may be important in the 

 recycling of nutrients that may otherwise occur as pollutants in the 

 estuary. 



151 



