Influences of Herbivory on Treeline under Changing Climate

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Influences of Herbivory on Treeline under
Changing Climate

• David M. Cairns1, Charles W. Lafon1, Jon Moen2
• 1Department of Geography
• Texas AM University
• 2 Department of Ecology and Environmental Science
• Umeå University

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• Project Development
• Funding Situation
• Contribution to PPS-Arctic
• Data Collected

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Nordic Treelines
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Plant Animal Interactions
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Hypotheses

• Contemporary spatial patterns in the density of
  mountain birch seedlings above the treeline
  correspond to spatial variations in reindeer
  populations within the region.
• Treelines in which the relative palatability of
  forage is shifted toward arboreal vegetation
  (e.g., birch treelines) should exhibit a Type II
  (sensu Cairns Moen 2004) response to herbivory
  pressure.
• Temporal variations in tree establishment above
  treeline have been influenced by both climate and
  herbivory.
• Fluctuations in herbivore activity (i.e.,
  reindeer density and autumnal moth outbreaks)
  influence tree growth.

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Study Site Locations
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• Project Development
• Funding Situation
• Contribution to PPS-Arctic
• Data Collected

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Funding Status

• Funded by NSF through August 2008
• Expect data collection in summer 2007

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• Project Development
• Funding Situation
• Contribution to PPS-Arctic
• Data Collected

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PPS Arctic Aims

• Understand the controls on the location and
  pattern of the tundra-taiga ecotone (TTE).
• Determine the effects of global change on the
  location of the TTE.
• Study the feedbacks between the character and
  location of the TTE and the global climate.

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• Project Development
• Funding Situation
• Contribution to PPS-Arctic
• Data Collected

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Study Sites
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Data Collected

• Reindeer activity line transects and pellet
  counts
• Adult trees 20 tree-ring cores collected at
  each location
• Saplings Two 10 x 50 m quadrats. All saplings
  lt 5 cm basal diameter sampled by cross section.

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Time Table

• Summer 2006
• Initial Field Data Collection
• Winter 2006/7
• Generation of master chronologies
• Cross dating of cores
• Determination of establishment dates
• Summer 2007
• Completion of Field Data Collection
• Winter 2007 / Spring 2008
• Continuation of tree ring analysis
• Summer 2008
• Project wrap up and publication