sites (Tab. 1 and Fig. 1). Site duplication spreads the risk, so that if 

 one site is destroyed not all the information is lost. 



Special measures of plant growth response are described for certain 

 experiments, but the following measures generally have been used to obtain 

 estimates of vegetative growth and development in the field: 



1. Aerial dry weight - oven dry weight of aboveground 

 growth per transplant (hill) or per unit area. 



2. Belowground dry weight (yield of rhizomes and roots) - 

 oven dry weight of belowground plant material (rhizomes and 

 roots) for entire transplant (hill) for first-year transplants; 

 for older plantings usually two cores were taken from each 

 quadrat harvested for aboveground growth. Samples were taken 

 to a depth of 30 centimeters with a stainless-steel coring tube 

 with an inside diameter of 8.5 centimeters. Samples were washed 

 and plant parts separated, weighed, and expressed as belowground 

 growth per transplant (hill) or per unit area. 



3. Number of flowers - flowering culms per transplant (hill) 

 or per unit area, gives some measure of vigor. 



4. Number of center culms - number of culms (stems) 

 clustered around the original transplant (hill) , recorded on 

 first-year transplants only. 



5. Number of rhizome culms - number of culms (stems) arising 

 from rhizomes, away from the original transplant (hill) , gives 

 some measure of spread, recorded on first-year transplants only. 



6. Height - distance from base to tip of culm in centimeters, 

 usually the average of five culms per sample. 



7. Basal area - area covered by culms (stems) at ground 

 level as determined by harvesting culms, holding them tightly 

 bunched and measuring their cross sectional diameter, then 

 determining cross sectional area; recorded per transplant (hill) 

 or per unit area. 



The exposed locations and unstable conditions of many study sites 

 rendered them more vulnerable to damage or total loss than is typical of 

 upland studies; hence, higher experimental errors are obtained from coastal 

 studies. Compensation for this problem was attempted through duplication 

 of field tests. Major hazards inflicting damage and loss were: storm 

 associated wave action, shifting of channels causing undermining, and 

 burial by windblown sand. 



III. PROPAGATION 



Spartina alterniflora invades new sites by both vegetative means and 

 by seeds. Pieces of marsh dislodged by water or ice may be deposited on 



15 



