Near Islands
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Transcript of Near Islands
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Western Aleutian Plant Distribution:
Buldir Island as a Dispersal FilterMonte Daniel Garroutte and Stefanie M. Ickert-Bond
University of Alaska Museum of the North & Department of Biology and Wildlife
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Near Islands
Rat Islands
Western Aleutian Islands
Buldir Island
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Buldir Island, AK• 26 breeding species of seabirds• 3 million + individual birds• Aleutian Cackling Goose
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Nutrient subsidy
Ocean Island
Nutrients
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Seabird Islands are nutrient subsidized;When compared to fox-infested islands:• ~3-fold increase in graminoid biomass• ~10-fold decrease in low-lying shrub biomass (Croll
et. al., 2005)
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Questions• What is driving the vegetation composition
on Buldir Island? – How does the vegetation differ in surface
nesting and burrowing seabird colonies?
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Seabird Vegetation Disturbance
BurrowingSurface Nesting
ErosionSoil compaction
Root damageSeedling trampling
Increased soil litter Decreased soil litter
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Seabird Vegetation Disturbance
Increasing homogenization: Decline of native woody and
herbaceous perennials
Introduction and expansion of annuals and colonizing plants
BurrowingSurface Nesting
Increased density
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Surface nester plotsGlaucous-winged Gull:
“Loafing areas”5-7 plant species per plot- Changes with elevationAnnual Callitriche sp. collected in 2007, in loafing area
246m elev.
55m elev.
196m elev.
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Burrow nester plotsLeach’s Storm PetrelsFork-tailed Storm PetrelsCassin’s AukletsAncient Murrelets~5 plant species in each plot -changes with slope, nest density
High Burrow Density Lesser Burrow Density
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Aleutian Plant Dispersal“Two Way Filter Bridge” (Carlquist, 1965)
Near Is. (US)
Rat Is. (US)
Commander Is. (Russia)
Buldir Is.
Commander Is. Rat IslandsNear Islands
Amphi-Pacific Amphi-PacificAmphi-Pacific
N.A.
N.A.
AsianAsianAsianN.A.
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Aleutian Plant Dispersal
Near Is. (US)
Rat Is. (US)
Commander Is. (Russia)
Buldir Is.
Proposed ConstraintsTime constraint:• Deglaciation • Eruptions
Distance barrier
Biotic Constraint:Seabirds as dispersal filters
71 Species not found in Rat Islands (25%)
Rat IslandsNear Islands
Amphi-PacificAmphi-Pacific
N.A.
N.A. Asian
91 Species not found on Near Islands (29%)
Asian
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Near Islands
Rat Islands
Hypothesis- Buldir Island acts as a dispersal filter between the Near and Rat Islands.
• Species that survive Buldir’s constraints will be dispersed• Near Islands Rat Islands dispersal is rare
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Sorbus sambucifolia
Antennaria monocephala
Buldir Island
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Methods: Phylogenetic Analyses
Phylogenetic approaches utilize the relatedness among species to infer assembly processes. Requires:• Knowledge of floral composition• A phylogenetic “supertree” built from floral composition and a
phylogenetic database• The identification of constraints
Phylogenetic analyses have been used to infer the distance barriers driving community composition in the Ryukyu Archipelago (Kubota et. al., 2011)
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* Amchitka graminoids added
Western Aleutian Islands by Plant # and Island Size
0 100 200 300 400 500 600 700 800 900 10000
50
100
150
200
250
300
Attu
Agattu
Buldir
Amchitka
Kiska*
Island Size (km 2)
Plan
t Spe
cies # Near Islands
Rat Islands
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Conclusions• The Western Aleutians are important for East-
West and West-East dispersal• The Rat islands and Near Islands are
floristically dissimilar• Buldir Island community assemblage is highly
constrained by seabird colonies
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Future Work• Complete Buldir seabird colony survey &
island flora (August 2011)• Complete phylogenetic analyses• More collecting in the Western Aleutians
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Near Islands
Rat Islands
Western Aleutian Islands
24
194
205
145
142270
2010 Survey• First collection of Saxifraga
unlaschensis• 226 collections (138 taxa)
Population samples• Therorhodion camtschaticum• Saxifraga foliolosa
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There are still several incomplete floras in the Western Aleutians
Semisopochnoi Island: • 60th largest Island in the United
States• 25 collections in ARCTOS, totaling 24
species
Attu Island 194 collected species
Kiska Island: Only ~6 graminoid species have been collected & reported (largest families in the Aleutians)
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Acknowledgements• Jeff Williams & Dr. Vernon Byrd of AMNWR• Herbarium – Jordan, Zach, Carolyn, Dave, Kelsey, Stephanie J.• Dr. Christa Mulder• Melody Durrett• Tiglax Crew• Ian Jones• Scott Freeman• 2010 Buldir FWS personnel
Funding• Acknowledgement to Alaska EPSCoR NSF award #EPS-0701898 and the
state of Alaska• Acknowledgement to FWS via AMNWR for travel and logistical support
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Questions?