higher live standing crops than do respective Big Island Bayou stations. Finally, both upstream 

 stations have proportionally higher standing crops of Scirpus olneyi than Spartina patens than do 

 the downstream stations. In addition, downstream stations consistently have a third plant species 

 component--v/««cuj roemerianus or Fimbristylis castanea. Although standing crop is herein defined 

 as the live plant material, stem counts and average lengths were also measured. Stem counts prove 

 to be less useful in estimating standing crop because plant width-to-length ratios vary with time of 

 year and among sites during the same sampling period. Dry weight measurements per unit area 

 are the only reliable quantifiable way to make comparisons in standing crop. 



No spatial patterns in belowground biomass could be detected. Average belowground biomass 

 was found to be 5010 gm/m 2 . Fifty-one percent of the roots were found in the 0- to 10-cm soil 

 interval. 



Salinity 



Marsh surface water salinity data are presented by season and by annual averages (Table 3). 

 Seasons were: winter= January-March; spring= April-June; summer= July-September; and fall = 

 October-December. This subdivision fits the seasonal temperature and plant growth cycles quite 

 well (e.g., Scirpus olneyi usually has three crops; one maturing in April, one in July, and one in 

 October) and allows comparison of the growth season salinity levels with crop biomass. 



Seasonally, salinity in the marsh is lowest during the winter and highest either in the spring or 

 summer depending upon rainfall, Gulf of Mexico salinities, and winds. Little difference existed in 

 mean salinity levels among years at each station except for BID. Salinities in 1985 in BID were 

 elevated because Hurricane Danny's storm tide waters did not drain from the marsh before 



Table 3. Annual mean marsh salinity summary, May 1985 through May 1987. 



Top number=annual mean salinity; bottom number=standard deviation; see Table 1 for 

 site abbreviations. 



b Paired data=salinity measurements taken at all stations within one work day. 

 c Complete data = all measurements of salinity taken at particular station. 



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