Figure 42. Aerial view of relict rice fields on former bottomland hardwood forests 

 that are presently managed for waterfowl. Photo courtesy of the Georgia Department of 

 Natural Resources. 



PRIMARY PRODUCTIVITY OF FLOODPLAIN FORESTS 



High productivities of the floodplain 

 forest (Conner and Day 1976) are made 

 possible by several subsidies offered to 

 the floodplain by the watershed and river, 

 including particulate and dissolved or- 

 ganic matter, water, soil (especially clay 

 and silt), and nutrients (inorganic, 

 sediment-adsorbed, and organically com- 

 plexed). These inputs support what is 

 essentially an increased rate of ecosystem 

 community metabolism, reflected in (1) 

 annual litterfall and nutrient turnover 

 rates as high or higher than most temper- 

 ate deciduous forests; (2) relatively high 



detrital decomposition rates, except in 

 systems with permanently ponded water; (3) 

 periodic "flushing" of accumulated refrac- 

 tory organic detritus and metabolic by- 

 products; and (4) the operation of several 

 microbial conversion processes character- 

 istic of widely varying conditions, such 

 as nitrification, denitrif ication, ammoni- 

 fication, methanogenesis, sulfate reduc- 

 tion, and general nutrient mineralization 

 (Wharton and Brinson 1979a). 



In addition to these physical and 

 chemical subsidies, the river contributes 

 macro- and microfauna during flood periods 

 that both speed detrital decomposition and 



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