Balsam fir (Abiesbalsamea (L.) Mill.) mortality caused by the last spruce budworm (Choristoneurafumiferana (Clem.)) outbreak (1970–1987) was studied in 624 sites belonging to a complex natural forest mosaic originating from different fires in northwestern Quebec. Multiple regression analyses were used to assess the respective effects of stand structure, species composition, site characteristics, and the forest composition surrounding the stand on observed stand mortality. Mortality was observed to increase in relation to diameter of the trees, basal area of balsam fir, and the number of stands dominated by conifers in the forest mosaic. All of these factors showed significant independent effects, but 60% of the variance remained unexplained. Site characteristics, however, did not show a significant relationship to stand mortality. The results suggest that forest composition at both the stand and the forest mosaic levels may be responsible for differing degrees of defoliation that result in differences in stand mortality. Forest management strategies that favor the presence of mixed compositions both at the stand level and at the mosaic level may contribute to decreased stand vulnerability.

SUMMARY:Thiamine and folate levels in blood and cerebrospinal fluid (CSF) were determined by microbiological assays in 23 control subjects and 11 phenytoin-treated epileptics. There was no significant difference between the two groups for serum and CSF folate levels. There was, however, a statistically significant difference between the groups for both whole blood thiamine and CSF thiamine levels. Epileptic patients being treated with phenytoin had lower values than control subjects (p < 0.001)

Female CD-1 mice were evaluated on three occasions over a nineteen month span in tests of exploration, motor coordination, and spatial orientation in a water maze. Aging decreased motor activity and exploration of specific environmental stimuli found in a hole-board and in a T-maze. Age-related deficits were also found in three motor coordination tasks (inclined grid, coat-hanger, and round bridge) and during retention but not acquisition of the hidden platform version of the water maze task. Performance on some motor coordination tests was linearly correlated with either motor activity or exploration, implying the existence of similar neurobiological pathways responsible for these age-related changes.