Richardson, C. J. Duke university, curtr@duke.edu
Qian, S. J. Portland state university,

 
PHOSPHORUS ASSIMILATIVE CAPACITY IN FRESHWATER WETLANDS: A NEW PARADIGM FOR MAINTAINING ECOSYSTEM STRUCTURE AND FUNCTION
 
We developed a P mass loading model from statistical analyses of a North American wetland data base (NAWDB). This model was used to separate P assimilative capacity (PAC, defined as P absorption with no significant ecosystem change and no elevated P output) from P storage capacity (maximum storage) in wetlands. Our analysis indicates that average PAC in North American wetlands is near 1 g m-2 yr-1. From the cross-sectional analysis we proposed a "One Gram Assimilative Capacity Rule" for P loadings within natural freshwater wetlands if long-term storage of P, maintenance of community structure and function, and low P effluent concentrations are required. An Everglades test site supports our hypothesis. Moreover, the natural wetlands will lose native species, become P saturated in a few years, and export unacceptable amounts of phosphorus, when P loading exceed PAC. Our findings clearly demonstrate that even P-limited wetlands have the capacity to assimilate low levels of P loadings without significant changes in ecosystem structure and function. P storage capacity in wetlands is much greater than PAC, but significant ecosystem changes will result when wetlands are exposed to P loadings above PAC capacity.
 
Day: Monday, Feb. 1
Time: 02:00 - 02:15pm
Location: Hilton of Santa Fe
 
Code: SS06MO0200H