Trophic effects of rainfall on Clethrionomys rutilus voles: an experimental test in a xeric boreal forest in the Yukon Territory
Dates
Year
2002
Citation
Carrier, Patrick, and Krebs, Charles J., 2002, Trophic effects of rainfall on Clethrionomys rutilus voles: an experimental test in a xeric boreal forest in the Yukon Territory: Canadian journal of zoology, v. 80, no. 5, 821 p.
Summary
The Kluane forest is unusual in that it is less productive than other boreal forests because it lies in a rain-shadow zone in the Yukon Territory. Densities of the boreal red-backed vole Clethrionomys rutilus are known to be food-limited in the Kluane region, and its food sources, mostly plants, could be rainfall-limited. Above-average rainfall in the Kluane region could reduce the summer water deficit, which would in turn enhance primary production and reduce food limitation in voles, ultimately leading to a population outbreak. We experimentally tested these two predictions by irrigating three sites in the boreal forest from 1995 to 1999, and concurrently comparing numbers of voles and availability of their potential food sources [...]
Summary
The Kluane forest is unusual in that it is less productive than other boreal forests because it lies in a rain-shadow zone in the Yukon Territory. Densities of the boreal red-backed vole Clethrionomys rutilus are known to be food-limited in the Kluane region, and its food sources, mostly plants, could be rainfall-limited. Above-average rainfall in the Kluane region could reduce the summer water deficit, which would in turn enhance primary production and reduce food limitation in voles, ultimately leading to a population outbreak. We experimentally tested these two predictions by irrigating three sites in the boreal forest from 1995 to 1999, and concurrently comparing numbers of voles and availability of their potential food sources such as mushrooms, understory vegetation, white spruce, Picea glauca trees, and forest-floor invertebrates between irrigated and nearby non-irrigated sites. Irrigation increased rainfall 91% above normal, on average. Neither understory plants, trees, invertebrates, nor the vole population reacted to irrigation. Only mushroom biomass increased. Nitrogen limitation is probably prevalent in the Kluane forest, as in boreal forests in general. However, mushroom biomass increased with irrigation in the Kluane forest and in turn should have increased nitrogen mineralization. Hence, irrigation should have reduced nitrogen limitation through its stimulation of decomposers. It is therefore unclear why plant production and vole numbers did not correlate with mushroom biomass on the irrigated sites.
