II-B-17 



Williams, R.B. and M.B. Murdoch. 1972. Compartmental analysis of 



the production of Juncus roemerianus in a North Carlina salt marsh. 



Chesapeake Science 13:69-79. 



Juncus roemerianus (needlerush) grows in the upper intertidal zone 

 of salt marshes and covers extensive areas along the shore of North Carolina 

 and elsewhere along the southeastern seaboard. Other species of Juncus are 

 important components of salt-marsh floras elsewhere in the world. As 

 part of a study of total plant production in the estuarine areas adjoining 

 Beaufort, N.C, the authors endeavored to measure the annual aboveground 

 production of a nearly pure stand of Juncus roemerianus . First the 

 standing crop was followed for a year by harvesting quadrats of Juncus . 

 When it became obvious that there were no pronounced seasonal cycles in 

 production, the growth and longevity of individual leaves was followed 

 for nearly 2 years. These data (obtained near Cape Lookout, North Carolina 

 during 1965 to 1968 on standing crop, growth rate, and longevity of above- 

 ground portions of needlerush) were synthesized into a three- compartment 

 linear mathematical model. Analysis of field observations yielded 

 average standing crops for live, dying and dead Juncus of 344, 504, and 

 1,604 g dry wt m-2^ respectively, and an annual production of 754 g dry wt m- 

 The model duplicated the average standing crops and annual production; 

 it also yielded seasonal cycles in the standing crops of the three 

 compartments, these cycles explaining much of the variations observed 

 during the field work. 



The seasonal changes in standing crop observed were generally similar 

 to those reported previously. Stroud and Cooper (1968) and Waits (1967) 

 also found the proportion of dead material least in the summer and greatest 

 in the winter. In all three studies the proportion of living material had, 

 of course, a reverse cycle. Foster (1968) reported that the number per 

 square meter of green and brown leaves was greatest in the summer and 

 least in the winter. These results agreed with the author's observations 

 on the seasonal cycle in biomass in the dying compartment. Foster's 

 observations on the number of green leaves indicated, however, a seasonal 

 cycle with a maximum in midsummer, whereas the reported seasonal cycle in 

 biomass had its maximum in the fall. This lack of agreement reflected 

 different in methods. (G.S.) 



Keywords: Juncus roemerianus , salt marsh, needlerush. North Carolina 



II-B-18 



Waits, E.D. 1967. Net primary production of an irregularly flooded 



North Carolina salt marsh. Ph.D. Thesis. North Carolina State University 



at Raleigh. 124 pp. (Diss. Abstr. 28:4027-B) 



The major vegetation types of an irregularly flooded salt marsh on 

 the Outer Banks of North Carolina were defined by analyzing species pres- 

 ence data obtained from sample plots. Six vegetation types were described 



45 



