4,680 g C/mVyr, most of 

 the einerjent grass. Net 

 tion was 3,670 g/m^/yr. 

 other figures comparable 

 direct measurement. 



which is due to 



primary produc- 



There are no 



to these from 



Net aboveground production from clip 

 plot studies is only about 850 g/m^/yr. 



leaving an estimated 2,800 g/mVyr under- 

 ground production. That is not impossible 

 but is certainly very high. Community 

 respiration was about 3,150 g/m^/yr, which 

 is not too different from the estimates of 

 Day et al . (1973) and Hopkinson and Day 

 (1977) of around 3000 g/mVyr; but in 

 their studies 90 percent of this was plant 



Table 29. Estimates of different components of the carbon budget of 

 a Mississippi deltaic salt marsh community (g C/m^/yr). 



Carbon flux Technique 



Reference 



Input 

 Gross community primary 



production 4,680 



Net plant primary production 



(above and belowground) 3,670 



Aboveground einergents 793 



578 

 871 

 1,158 

 Mean 850 



Belowground production 2,820 



Output 



Community respiration 



Emergent plant respiration 

 Consumers 



Leaching from live plants 

 Methane production 

 Lost to deep sediments 



3.150 

 3,081 



1,010 

 2,750 



2,140 

 302-316 



140 



5 

 265 



Balance (export and unaccounted) 

 Net community production 1,260 



300 

 300 

 150 



CO2 flux 



II M 



CI ip plot 

 11 II 



M II 



II II 



II II 



Difference (3,670-850) 



a 

 b 

 c 

 d 



Mean 



CO2 flux a 

 Sed. oxygen flux 



& calc. pi ant resp. f ,g 



CO2 flux a 

 calculated from 



other studies f,g 



CO2 difference a 

 Oxygen flux & calc. 



for large consumers f,g 



Leaching studies i 



Methane flux h 

 Subsidence rate 



X sed. C content j 



from CO 2 a 



from organic balance f,g 



from N bal ance j 

 from estuary export 



& bay P:R ratio k 



References : 



a - Gossel ink et al . 1977 and unpubl. 



b - Kirby 1971 



c - Kaswadji 1982 



d - Hopkinson et al. 1978 



e - White et al . 1978 



f - Hopkinson and Day 1977 



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