Small Rodent Populations and Conifer Seedling Damage on a Reclaimed Area in West Central Alberta

Abstract

Small rodent populations and conifer seedling survival were monitored on a reclaimed area in west central Alberta from September 1979 to September 1985. Although several species of cricetid rodents and shrews were captured during the live-trapping program, only meadow voles (Microtus pennsylvanicus) and deer mice (Peromyscus maniculatus) occurred in sufficient number to monitor annual changes in abundance. Meadow voles increased rapidly on the reclaimed area from 1979–1981, remained at high numbers until 1984, then declined sharply in 1985. Deer mice increased to moderate numbers from 1979–1981 and declined gradually until 1983. By 1984–1985, very few deer mice were present.Two species of conifer seedlings, lodgepole pine (Pinus contorta) and white spruce (Picea glauca) were planted on the reclaimed area in 1979 and 1980. Numbers of seedlings killed or damaged by small rodents, primarily by girdling, increased sharply in 1981 and remained at high levels through to 1984. Significant correlations between the percentage of the annual mortality of seedlings attributed to small rodents or the percentage of live seedlings damaged by small rodents, and the abundance of meadow voles the previous winter, indicate that the amount of mortality and damage to seedlings in this reclamation area is in part determined by the overwintering abundance of meadow voles. This is in direct agreement with conclusions from similar studies in other areas of North America and Europe.

Retention of cotyledons is crucial for resprouting of clipped oak seedlings

“…This may suggest that the amount of metabolizable biomass in cotyledons acts as backup reserves for growth and survival of seedlings in the presence of various environmental disturbances 11 26 27 28 29 . Among these disturbances, seedling browsing and clipping by livestock and rodents have apparently contributed to seedling damage in the fields 6 30 31 . However, resprouting is the main regeneration mechanism of most Quercus species after severe disturbances 32 .…”

Winter herbivory by voles during a population peak: the importance of plant quality

“…Arctic and subarctic ecosystems are characterized by substantial variation in plant community structure and plant species composition, both on local and landscape scales (Bliss and Matveyeva 1992, Oksanen and Virtanen 1995, Virtanen et al 1997). This variability in habitat characteristics in turn affects the distribution of small mammal herbivores (Batzli 1983, Batzli and Lesieutre 1991, Oksanen et al 1999) and, as a consequence, interactions between these herbivores and their food plants (Kennedy et al 1989, Ida and Nakagoshi 1996, Hambäck et al 1998). The spatial variability in plant‐herbivore interactions is well‐known from small‐scale exclosure experiments where effects of removing small mammal herbivores on plant growth and biomass often show substantial variability both between replicates and between localities (e.g., Oksanen and Moen 1994).…”