SECTION I 



CONCLUSIONS 



The primary conclusions from studies on this project 

 can be summarized as follows: 



1. Plant analysis is a relatively simple and useful 

 procedure for evaluating nutrient supplies and growth- 

 limiting nutrients for nuisance macrophytes , and 

 probably for other obnoxious plants as well. 



2. Plant analysis is most reliable as a diagnostic 

 technique when based on the index segments established 

 in these studies (the first and second one-inch 

 segments of stems and laterals) rather than on entire 

 plants. 



3. Establishing critical concentrations for most of the 

 essential elements in Elodea occidentalis makes it 

 possible to use this species as a general bioassay 

 organism in evaluating whether any of these elements 

 become growth-limiting in lakes or streams. 



4. Evaluations of nutrient supplies in Wisconsin lakes 

 indicated neither nitrogen nor phosphorus was a 

 general limiting nutrient in the lakes sampled. 



5. The element most likely to limit macrophyte growth 

 varied in different lakes. Evidence was obtained that 

 nitrogen, phosphorus, calcium, and copper were limiting, 

 or were close to growth-limiting, in different lakes. 



6. Although confirming evidence is required, the results 

 indicated copper deficiency is common in soft-water, 

 infertile northern Wisconsin lakes. 



