DISCUSSION 

 Odum: 



Smalley: 



Odum: 



Davis: 



Smalley: 



Davis: 



Teal: 



Davis : 



Teal: 



Smalley: 



If you take the slope of the standing crop graph of living Spartina, 

 not the dead, what would the rate in gms/unit of time look like on 

 a year's basis? Would you get a net production excess at the 

 time of appearance of dead material? Try to see from these 

 graphs whether you can compute the rate of export of organic 

 matter or not. 



I don't think you can say you are exporting organic matter from 

 the marsh because export is a function of detritus in the water. 

 I will not say that the Spartina marsh is a system in itself. The 

 matter of export in the salt marsh-estuarine system is a matter 

 of sedimentation and export to the sea and I do not know that. 



From your graph it appeared that in the spring you had the fast- 

 est growth - it looked like April. Taking your figure off the 

 graph it works out to be 13 grams per square meter per day net 

 growth and that isn't far from the maximum growth of Chlorella 

 cultures in a steady state that Tamiya has reported in a recent 

 summary. Thus it looks like marsh growth may be of the same 

 order of magnitude as the best yields in laboratory photosynthesis. 



There is one factor that I have been wanting to mention that has 

 not been stressed. That is the loss by simple oxidation. Any 

 substance like peat or any inert substance or organic matter is 

 going to lose weight. I do not know how you are going to handle 

 that. In this whole eco-system business, as you get toward the 

 tropics you do not get any leaf mold at all, because in your trop- 

 ical A horizon there is no A horizon at all. Another trouble is 

 comparing underwater productivity with above water because you 

 won't get oxidation under water and you will above water. So you 

 take Tom Odum's figures for Silver Springs and your figures for 

 these Spartina marshes, and you are comparing two entirely dif- 

 ferent habitats. One is subject to oxidation without any apparent 

 way of measurement. 



This does not inake any difference in the production of the grass. 



No, but it makes a difference, 



On what happens to it afterwards. 



That is right and you use the word "decomposition". 



I will talk about that. 



We did not use the figure supplied from the graph's data for the 

 bacterial decomposition. 



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