Landscape Analysis of Treeline Dynamics in Southwest Yukon

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PPS-Arctic Canada
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Canada West
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Yukon Research (Johnstone)

• Field Sites
• Eagle Plains, Dempster Highway
• 2005 Burn near latitudinal treeline
• Undisturbed treeline surveys
• Old Crow
• Latitudinal/altitudinal treeline
• Undisturbed treeline surveys
• Community plant use workshop
• Graduate student
• Carissa Brown, Ph.D. student (started Jan. 2007)
• Thesis Disturbance and climate effects on
  treeline vegetation

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Research Objectives (Johnstone)

• Disturbance effects on treeline dynamics
• Latitudinal treeline (Picea mariana)
• Emphasis on tree recruitment processes
• Response to climate warming
• Approach
• Seeding trials with multiple species
• Disturbed/undisturbed comparison
• Levels of disturbance severity
• Small scale warming
• Surveys of natural regeneration

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Research Objectives (Johnstone)

• Vegetation structure of current treeline
• Age structure analysis gt recent treeline change
• Permanent plots for vegetation monitoring
• 3 blocks of 6 plots est. 1997 in Old Crow
• soil temps in treed plots
• Environmental gradients across treeline
  boundaries
• Soil temperature, nutrient pools, snow (?)

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Scott Green
Trajectories of existing populations -isolated
populations vs contiguous forest -extended
photoperiod impacts on water
relations Regeneration -species/population
suitability -facilitation/competition
-disturbance
Potential methodologies 1) Tree rings 2)
Common-garden studies and provenance
trial 3) Leaf-level physiology
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PPS Arctic Canada Treeline Research Mackenzie
Delta Region

• Objectives
• Determine changes in white spruce reproduction
  through treeline
• Determine changes in density of tree islands at
  individual and landscape scales.
• Determine establishment periods and relations to
  climate in white spruce populations through
  treeline
• Contribute to PPS Arctic common studies

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Approaches

• Relocate and re-measure tree islands studied in
  early 1990s by K McLeod
• Growth, cone and seed production, germination,
  seed banks
• Survivorship of seedlings planted in 1993
• Use disks collected in 1990s 2008 compare
  chronologies
• Measure age and spatial structure of forest
  stands through treeline in Tuk region
• Has there been an increase in density of saplings
  in the forest tundra over the past decade?
• Establish permanent plots
• Use repeat air photos along transects
• Experimental studies
• Warming by OTCs around established saplings
• Snow fences to alter snow depth
• Transplant experiments for longer term monitoring

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Sites used in 1990s for studies of white spruce
through treeline
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Germination rates of white spruce seeds collected
from sites through treeline in 1993-95. Have
these rates changed over the last 15 years?
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Effect of location on survivorship of planted
seedlings of white spruce at three tree island
sites in the Tuktoyaktuk region. Seedlings were
planted inside the tree island or at least 1 m
from the edge of the tree island. Survivorship
was assessed two years after planting.
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Mackenzie Mountains
Churchill
ACIA 2005
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• Since 1990

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Mackenzie Mountains NWT
Krummholz
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Long-Term Environmental Monitoring Sites

• Natural ecosystems
• TUN Undisturbed Tundra
• TIS Forest-Tundra Tree Island
• FEN Fen (wetland)
• WSU White Spruce Upland Forest
• BSW Black Spruce Wetland
• PPA Polygonal Peat Plateau
• Aggrading permafrost in a tundra peatland
• Naturally-disturbed ecosystems
• PPD Polygonal Peat Plateau
• Degrading permafrost in a tundra peatland
• BFR Burned White Spruce Upland Forest
• Anthropogenically-disturbed ecosystems
• BWP naturally-recovering Borrow Pit in the
  forest
• Reclamation test treatments
• PFR Planted Burned Forest
• PN Pit Nicole
• PP Pit Ptarmigan
• PL Pit Launch

Seedlings
Seedlings
Dendroclimate
Since 2000
Seedlings
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Churchill MB
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Rod Savidge
Lat. 62.09931, Long. -137.20435
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1947
1969
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Alaska
Yukon
Gulf of Alaska
B.C.
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Kluane Field Studies

• Build on recently completed field study of stand
  dynamics and experimental warming through
• Experimental manipulations (shrub cover
  alteration, transplants, etc.)
• Seedling microhabitat modeling
• Long term monitoring plots
• Repeat photography

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Scaling Up

• Explore relationship between spatial
  heterogeneity of treeline ecotone and
  environmental/biological variables at multiple
  (6) sites across Canada
• Use nested remotely sensed imagery to scale-up
  from field observations/data to landscape,
  regional and national scales
• MODIS / Landsat / ASTER / Quickbird

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Yukon Research Synergies

• Questions
• Disturbance and treeline dynamics
• Shrub component
• Seed production, viability, germ plasm
• Field Methods
• Environmental site measurements/monitoring
• Experimental manipulations
• Dendrochronology