DATE 



F-lguve 5. — Seasonal variation of seedling deaths due to severed stems (cutworms) and 



severed cotyledons (birds and small mammals). 



Approximately 20 percent of the seedlings turned brown and became very brittle with 

 no obvious cause. This type of casualty was common on nearly all treatments. There 

 was no relationship between open versus canopy, or the presence or absence of litter 

 with this type of mortality. Possible causes were heat stress, root death due to too 

 much soil moisture or undetected root pathogens, or perhaps the expression of a lethal 

 gene. 



The disappearance of seedlings accounted for 10 percent of the losses. As men- 

 tioned earlier, this could have been the work of cutworms which devoured the entire 

 seedling. The greatest number of disappearances occurred in treatments where there was 

 ground litter or cover which was considered earlier as an important factor for cutworm 

 presence, and where it was more difficult to find the evidence of chewed seedling 

 remains . 



The remaining four casualty classes--poor root development, sun scald, damping-off, 

 and miscellaneous--were responsible for 13 percent of total seedling deaths. Poor root 

 development had its greatest effect in the opening-cleared treatment and very little 

 effect elsewhere. Sun scald was associated with plots receiving the greatest amounts 

 of sunlight. Conversely, damping-off was more prevalent in plots with heavy shade and 

 deep litter. 



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