Appendix B. A description of white spruce cone crops that were rated in Alberta-based forestry publications as well as supplemental information on interpreting squirrel harvest records.
Chronological order of years for which cone crops of white spruce were rated in Alberta-based forestry publications. Cone crops that were described in these studies as "high," "heavy," "good," or "excellent" were classified as mast years, while all years described by other terms were classified as non-mast years. The cone ratings are classified as: (1) anecdotal for ratings without data, (2) localized data when sites were few or close by, and (3) extensive data when many sites greater than 50 km apart were assessed. These data were used primarily for comparison purposes with cone survey and red squirrel trapping data.
| 1948–1953 localized data |
Crossley, D. 1955. Survival of white
spruce reproduction resulting from various methods of forest soil scarification.
Technical note 10. Department of Northern Affairs and National Resources, Forestry
Branch, Alberta, Canada. |
| 1951–1953 anecdotal |
Quaite, J. 1956. Survival of white
spruce seedlings resulting from scarification in a partially cut mixedwood stand.
Technical note 44. Forest Research Division, Calgary, Alberta, Canada. |
| 1952–1955, 1957–1958 anecdotal |
Lees, J. C. 1963. Partial cutting
with scarification in Alberta spruce-aspen stands. Department of Forestry publication
1001. Forest Research Branch, Ottawa, Ontario, Canada. |
| 1959–1967 extensive data |
Kemp, G. A., and L. B. Keith. 1970.
Dynamics and regulation of red squirrel (Tamiasciurus hudsonicus) populations.
Ecology 51:763–779. |
| 1966–1968 localized data |
Rusch, D. A., and W. G. Reeder. 1978. Population ecology of Alberta red squirrels. Ecology 59:400–420.
|
| 1979 localized data |
Cerezke, H. F., and R. E. Holmes.
1986. Control studies with carbofuran on seed and cone insects of white spruce.
Information report NOR-X-280. Northern Forestry Centre, Edmonton, Alberta, Canada.
|
| 1993–1996 extensive data |
Stewart, J. D., S. M. Landhausser, K. J. Stadt, and V. J. Lieffers. 2000. Regeneration of white spruce under aspen canopies: seeding, planting and site preparation. Western Journal of Applied Forestry 15:177–182. |
Supplemental information on interpreting squirrel harvest records
Squirrel population peaks coincide with peaks in cone records, and populations are low in poor cone years. This is an anticipatory reproductive response (i.e., there is no lag) that appears to be induced by increased availability of immature cones in the year prior to cone maturation. For further information on this topic, see Kemp and Keith (1970) and Rusch and Reeder (1978).
Market factors do not appear to have influenced the usefulness of red squirrel trapping records for identifying peaks in their population between 1941–1965, hence our use of these records for identifying the 1941 mast and 1942 non-mast year is justified. Analyses indicate that there was a weak negative correlation between fur returns and market price over this time period; so high harvests were more likely to reduce price, rather than the reverse (Kemp and Keith 1970). Thus the peaks in the squirrel records are likely a conservative indication of the extent to which their populations responded to masting in white spruce. See Todd and Giesbrecht (1979) for further discussion of fur returns and market factors.
LITERATURE CITED
Kemp, G. A., and L. B. Keith. 1970. Dynamics and regulation of red squirrel (Tamiasciurus hudsonicus) populations. Ecology 51:763–779.
Rusch, D. A., and W. G. Reeder. 1978. Population ecology of Alberta red squirrels. Ecology 59:400–402.
Todd, A., and L. Giesbrecht. 1979.
A review of Alberta fur production and management, 1920–1921 to 1977–1978.
Alberta Energy and Natural Resources, Fish and Wildlife Division, Edmonton,
Alberta, Canada.