Table 14. Belowground biomass of Mississippi Delta narsh plant spe- 

 cies (g dw/m^). 



*Percentage of total biomass. 



References : 



a - White et al . 1978 



b - Payonk 1975 



c - Sasser et al . , LSD, unpubl 



d - Johnson et al. LSU, unpubl. 

 e - Mendelssohn, LSU, unpubl. 



where, for example, S_. al terni flora 

 root:shoot ratios increase from 1-8 

 streamside to 1.2 - 49 inland (Good et al. 

 1982). 



As vn'th root biomass estimates, 

 aboveground production estimates vary 

 widely, even for a single species. Again 

 this is partly because of methodological 

 problems. Production is calculated from 

 at least two sets of measurements - 

 biomass and sone measure of mortality 

 during the interval between sampling. The 

 latter introduces a large element of 

 uncertainty in the estimate. One study 

 can generate several estimates that vary 

 from each other by as much as a factor of 

 three, depending on the assumptions made. 

 Shew et al. (1931) have an excellent 

 discussion of this topic. For example 

 Kaswadji's (1982) study was designed to 

 compare four different techniques for 

 detemiining production in a S^. 

 al terni flora marsh. The four methods 

 resulted in estimates of annual production 



(g/m2) varying fron 641 to 2,220 (Table 

 15). The higher estimates are commonly, 

 but not universally, considered the more 

 realistic in gulf coast marshes. 



Aside from tlie variation in reported 

 production due to the nethods of analysis. 



Table 15. Production estimates for a 

 Spartina al terni flora stand based on 

 different techniques (Kaswadji 1982). 



Technique 



E s t i na te 



^See Table 13 for references to tech- 

 niques. 



48 



