I certify that I have read this study and that in my opinion it 

 conforms to acceptable standards of scholarly presentation and is 

 fully adequate, in scope and quality, as a dissertation for the degree 

 of Doctor of Philosophy. 



Frank G. Nordlie, Chairman 

 Professor of Zoology 



I certify that I have read this study and that in my opinion it 

 conforms to acceptable standards of scholarly presentation and is 

 fully adequate, in scope and quality, as a dissertation for the degree 

 of Doctor of Philosophy. 



Claire L. Schelske 



Carl S. Swisher Professor of Water 



Resources 



I certify that I have read this study and that in my opinion it 

 conforms to acceptable standards of scholarly presentation and is 

 fully adequate, in scope and quality, as a dissertation for the degree 

 of Doctor of Philosophy. 



Daniel E. Canfield, J* 



Professor of Forest Resources and 



Conservation 



