Conclusion 



This study describes a fairly simple structure that forest 

 managers can use to assign relative mortality risks to indi- 

 vidual trees threatened with infestation by gypsy moth. A 

 tree's crown condition, crown position, and species group 

 are the only information items needed to assign probabili- 

 ties of death. This information will allow better evaluation of 

 silvicultural proposals aimed at adjusting forest stand struc- 

 ture to reduce risks of mortality. 



Literature Cited 



Campbell, Robert W.; Sloan, Ronald J. 1977. Forest stand 

 responses to defoliation by the gypsy moth. Forest 

 Science Monograph. 19: 1-34. 



Herrick, Owen W. 1982. Hazard rating forest trees threat- 

 ened with gypsy moth invasion. In: Proceedings of 

 coping with gypsy moth; 1982 February 17-18; University 

 Park, PA. University Park, PA: The Pennsylvania State 

 University: 38-42. 



Herrick, Owen W.; Gansner, David A.; DeBald, Paul S. 1979. 

 Predicting forest stand losses from the gypsy moth: an 

 application of automatic interaction detection (AID). 



Journal of Forestry. 77(2):91-94. 



Houston, David R.; Valentine, Harry T 1977. Comparing and 

 predicting forest stand susceptibility to gypsy moth. 



Canadian Journal of Forest Research. 7(3):447-461. 



Sonquist, John A.; Baker, Elizabeth L.; Morgan, James N. 

 1973. Searching for structure. Ann Arbor, Ml: Survey 

 Research Center, Institute Society of Research, Univer- 

 sity of Michigan. 236 p. 



Northeastern Forest Experiment Station 

 370 Reed Road, Broomall, PA 19008 



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