Claim: Twentieth century warming allowed moose to colonize the Alaskan tundra

“The average shrub height in 1860 is only an estimate, which is a limitation of the study.” Not science. An unverifiable hypothesis.

The media release is below.

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Twentieth century warming allowed moose to colonize the Alaskan tundra
Warming increased shrub availability for foraging, allowed moose to colonize hundreds of miles of tundra

PLOS

The establishment of moose in tundra regions of Alaska was the result of warmer and longer summers that increased their shrub habitat, according to a study published April 13, 2016 in the open-access journal PLOS ONE by Ken Tape from the University of Alaska, USA, and colleagues.

Moose, an iconic wildlife presence throughout Alaska, were actually absent from its tundra regions earlier in the 20th century. It was previously speculated that overhunting was responsible for this absence.

In the tundra landscape characterized by very short plants, moose must forage on shrubs sticking up above the snow during winter to survive. The authors of the present study therefore wanted to investigate whether a lack of available shrub vegetation was an alternative explanation for the previous absence of moose in the tundra. They used recent changes in shrub cover and relationships between shrub height and summer temperature to estimate the available moose habitat in Arctic Alaska around 1860, to compare it to that available in 2009.

The researchers estimated that average shrub height has increased since 1860 from around 1.1m to around 2m, greatly increasing the available forage sticking up above the snow. They therefore suggest that shrubs prior to the 20th century were too short and sparse in the tundra to support moose. They posit that as shrub habitat has increased as a result of twentieth century warming extending the summer growing season, moose have moved northward into tundra regions.

The average shrub height in 1860 is only an estimate, which is a limitation of the study. Nonetheless, the study provides evidence that shrub availability may explain the 20th century colonization of the tundra by moose. The authors suggest that the northward shift of moose in Alaska by hundreds of miles may be one of the most dramatic wildlife changes linked to climate change.

Ken Tape notes, “Although scientists have been anticipating changes to wildlife in response to the observed changes climate and vegetation of the Arctic, this is one of the first studies to demonstrate it. We showed that the large-scale northward shift of moose was likely in response to their increasing shrub habitat in the tundra.”

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Adapted by PLOS ONE from release provided by the author.

In your coverage please use this URL to provide access to the freely available paper: http://dx.plos.org/10.1371/journal.pone.0152636

Citation: Tape KD, Gustine DD, Ruess RW, Adams LG, Clark JA (2016) Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat. PLoS ONE 11(4): e0152636. doi:10.1371/journal.pone.0152636

Funding: KDT was supported by EPSCoR NSF award #OIA-1208927. DDG and LGA received support from U.S. Geological Survey’s Changing Arctic Ecosystem Initiative within the Wildlife Program of the Ecosystem Mission Area. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

3 thoughts on “Claim: Twentieth century warming allowed moose to colonize the Alaskan tundra”

  1. I can “prove” anything if I am permitted to make an “estimate” [read; fudge the data] for the primary baseline of my thesis.

  2. Along with musk oxen, moose (aka ‘elk’ in Eurasia) are probably the last of the surviving mega fauna from the Holocene extinction about 12,000 years ago. Their range is between latitudes 45° N and 70° N (inside the Arctic circle). In some areas they were hunted to extinction or nearly so, but have been reintroduced and have recovered.
    They have never been bothered by cold, and do not need a trivial warming to make their old habitats habitable again. They do not thrive where permafrost (N. Canada, Siberia) or permanent ice cover (Greenland) prevents forage from growing.

  3. I am reminded of a study a couple of years back that a herd of over 1000 had disappeared, blamed on humans. Retracted when a neighboring herd was found to have increased by the same amount.

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