Trophic Dynamics of the Boreal Forests of the Kluane Region

Charles Krebs, Rudy Boonstra, Stan Boutin, A Sinclair, James Smith, B. Gilbert, Kathy Martin, Mark O'Donoghue, Roy Turkington

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The trophic dynamics of the Yukon boreal forest have been under investigation at the Kluane Lake Research Station since 1973. We monitored and conducted experiments on the major species in this ecosystem, except the large mammals (for logistic reasons). The central problem has been to determine the causes of the 9 – 10 year cycle of snowshoe hares, and to achieve this we carried out several large-scale experiments manipulating food supplies, predator pressure, and soil nutrient availability to test hypotheses that food, predation, or habitat quality regulate populations. The hare cycle is driven top-down by predators, and most hares die because they are killed by predators. Predators also cause stress in female hares, and the stress response seems to be responsible for the loss of reproductive potential in the decline and low phases of the hare cycle. Many of the specialist predators and some herbivores in this ecosystem fluctuate with the hare cycle. Arctic ground squirrels do, but red squirrels do not, being linked closely to white spruce seed masting years. Small rodents fluctuate in numbers in two patterns. Red-backed voles and four species of Microtus voles have a 3 – 4 year cycle that seems to be driven by food supplies and social behaviour. Deer mice, in contrast, have fluctuated dramatically in the 38 years we have monitored them, but not cyclically. White spruce seed production varies with temperature and rainfall, but was not affected by adding nutrients in fertilizer. Global warming and reduced hare browsing in the last 20 years have helped to increase the abundance of shrubs in these forests. It will be challenging to predict how this system will change as climatic warming proceeds, because even closely related species in the same trophic level respond differently to perturbations. We recommend continued monitoring of the major species in these boreal forests.
Original languageEnglish
Pages (from-to)71-81
Number of pages11
JournalArctic
Volume67
DOIs
Publication statusPublished - 2014
Externally publishedYes

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hares
boreal forests
boreal forest
predator
predators
food supply
Picea glauca
squirrels
global warming
masting
seed productivity
reproductive potential
ecosystem
Lepus americanus
social behavior
browsing
Peromyscus
seed production
habitat quality
Yukon Territory

Cite this

Krebs, C., Boonstra, R., Boutin, S., Sinclair, A., Smith, J., Gilbert, B., ... Turkington, R. (2014). Trophic Dynamics of the Boreal Forests of the Kluane Region. Arctic, 67, 71-81. https://doi.org/10.14430/arctic4350
Krebs, Charles ; Boonstra, Rudy ; Boutin, Stan ; Sinclair, A ; Smith, James ; Gilbert, B. ; Martin, Kathy ; O'Donoghue, Mark ; Turkington, Roy. / Trophic Dynamics of the Boreal Forests of the Kluane Region. In: Arctic. 2014 ; Vol. 67. pp. 71-81.
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Krebs, C, Boonstra, R, Boutin, S, Sinclair, A, Smith, J, Gilbert, B, Martin, K, O'Donoghue, M & Turkington, R 2014, 'Trophic Dynamics of the Boreal Forests of the Kluane Region', Arctic, vol. 67, pp. 71-81. https://doi.org/10.14430/arctic4350

Trophic Dynamics of the Boreal Forests of the Kluane Region. / Krebs, Charles; Boonstra, Rudy; Boutin, Stan; Sinclair, A; Smith, James; Gilbert, B.; Martin, Kathy; O'Donoghue, Mark; Turkington, Roy.

In: Arctic, Vol. 67, 2014, p. 71-81.

Research output: Contribution to journalArticle

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T1 - Trophic Dynamics of the Boreal Forests of the Kluane Region

AU - Krebs, Charles

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AU - Boutin, Stan

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AU - Smith, James

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AU - Martin, Kathy

AU - O'Donoghue, Mark

AU - Turkington, Roy

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AB - The trophic dynamics of the Yukon boreal forest have been under investigation at the Kluane Lake Research Station since 1973. We monitored and conducted experiments on the major species in this ecosystem, except the large mammals (for logistic reasons). The central problem has been to determine the causes of the 9 – 10 year cycle of snowshoe hares, and to achieve this we carried out several large-scale experiments manipulating food supplies, predator pressure, and soil nutrient availability to test hypotheses that food, predation, or habitat quality regulate populations. The hare cycle is driven top-down by predators, and most hares die because they are killed by predators. Predators also cause stress in female hares, and the stress response seems to be responsible for the loss of reproductive potential in the decline and low phases of the hare cycle. Many of the specialist predators and some herbivores in this ecosystem fluctuate with the hare cycle. Arctic ground squirrels do, but red squirrels do not, being linked closely to white spruce seed masting years. Small rodents fluctuate in numbers in two patterns. Red-backed voles and four species of Microtus voles have a 3 – 4 year cycle that seems to be driven by food supplies and social behaviour. Deer mice, in contrast, have fluctuated dramatically in the 38 years we have monitored them, but not cyclically. White spruce seed production varies with temperature and rainfall, but was not affected by adding nutrients in fertilizer. Global warming and reduced hare browsing in the last 20 years have helped to increase the abundance of shrubs in these forests. It will be challenging to predict how this system will change as climatic warming proceeds, because even closely related species in the same trophic level respond differently to perturbations. We recommend continued monitoring of the major species in these boreal forests.

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KW - red-backed voles (Myodes rutilus)

KW - Microtus spp.

KW - Arctic ground squirrels (Urocitellus parryi)

KW - red squirrels (Tamiasciurus hudsonicus)

KW - grouse

KW - fertilization

KW - predation.

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DO - 10.14430/arctic4350

M3 - Article

VL - 67

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Krebs C, Boonstra R, Boutin S, Sinclair A, Smith J, Gilbert B et al. Trophic Dynamics of the Boreal Forests of the Kluane Region. Arctic. 2014;67:71-81. https://doi.org/10.14430/arctic4350