Table 30. 

 al terni flora 



Influence 

 plants on 



of Spartina 

 recovery of 



•'^N- ammonium added over 18 weeks to soil 

 cores (Buresh et al. 1982) . 



Recovery of added N 



Soil Aboveground Total 



tissue 



Includes belowground tissue. 



The overall N budget for a salt marsh 

 is summarized in Figure 64. There is a 

 large reserve in the sediment. New N is 

 introduced in particulate fonn in tidal 



water. DeLaune et al . (1981) estimated 

 this source to be about 23 g/m^/yr from 

 the N concentration in sediment trapped in 



shallow pans 

 mul tipl ied by 

 detennined from 

 sediments are a 



■>et 

 the 

 i^'Cs 

 sink 



marshes are subsiding 

 quite accurately from 

 about 16 g/m^/yr. 

 surface water, the 

 balance the budget, 



into the marsh, 



sedi.iientation rate 



profiles. The deep 



for N, because the 



This loss, known 



^"Cs profiles, is 



Nitrogen export in 



amount needed to 



is 14 g/mVyr. 



Presumably this is primarily bound up in 

 organic fonn. Notice that there are no 

 estimates of the flux of dissolved N in 

 the water column. Nobody has made even a 

 first order estimate of that. 



Phosph orus 



At first glance the P budget appears 

 to be much less complex than the N budget. 



PLANT TOP 



ISOOgOM 

 13gN 

 1.3gP 



PRODUCTION 



y , 2900qOM 



N FIXATION^ ° ^5^ 



1 IgN 



OVERLAND FLOW 



23gN 

 2.5gP 



-\— \-l ► 



1450gOM\ I 



DENITRIFICATION 



OVERLAND FLOW 



14 OgN 

 6gP 



PERMANENT SINK 



1 5gN 

 1.75gP 



Figure 64. Nitrogen and phosphorus budgets for a Mississippi deltaic salt marsh 

 (adapted from DeLaune and Patrick 1979). 



76 



