To determine the influence of small mammals on direct seeding, 2,000 seeds of Picea glauca (Moench) Voss were treated with the radioisotope Scandium 46 and placed in their natural environment in early June on two cutover areas near Hinton, Alberta. Each seed carried a tag of 3 microcuries and emitted an average gamma radiation of 10,000 counts per minute at the time of tagging. A sensitive portable scintillometer was used to re-locate the seeds three times during the summer months. Twenty-eight percent of the seeds had been moved from the original points of placement. Maximum recorded movement was 49 inches horizontally and 15 inches in depth through the soil (9 percent of the seeds were lost so actual movement may have been greater than 49 inches). After 17 weeks, whole seeds and hulls were dug up with small quantities of soil and taken into the laboratory for extraction and microscopic examination. A total of 1,819 seeds, approximately 91 percent, were recovered. Recovered seeds were compared with seeds of known fates and classified accordingly. Of the seeds recovered, 21 percent showed no change, 6 percent had germinated, 24 percent had dried up and 49 percent had been destroyed (35 percent by mice, 9 percent by chipmunks, 3 percent by shrews and 2 percent by insects). Destruction and drying up accounted for 73 percent of the recovered seeds. Small mammal studies were carried out on the same study areas to correlate population levels and species present with seed losses.
Document Type: Journal Article
Wildlife Biologist, Canada Dept. of Northern Affairs, Natural Historic and Resourses Branch, Canadian Wildlife Service, Edmonton, Alberta