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Near Islands

Western Aleutian Plant Distribution: Buldir Island as a Dispersal Filter Monte Daniel Garroutte and Stefanie M. Ickert-Bond University of Alaska Museum of the North & Department of Biology and Wildlife. Western Aleutian Islands. Near Islands. Buldir Island. Rat Islands. Buldir Island, AK.

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Near Islands

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  1. Western Aleutian Plant Distribution: Buldir Island as a Dispersal FilterMonte Daniel GarroutteandStefanie M. Ickert-BondUniversity of Alaska Museum of the North & Department of Biology and Wildlife

  2. Western Aleutian Islands Near Islands Buldir Island Rat Islands

  3. Buldir Island, AK • 26 breeding species of seabirds • 3 million + individual birds • Aleutian Cackling Goose

  4. Nutrient subsidy Ocean Island Nutrients

  5. Seabird Islands are nutrient subsidized; • When compared to fox-infested islands: • ~3-fold increase in graminoidbiomass • ~10-fold decrease in low-lying shrub biomass (Croll et. al., 2005)

  6. Questions • What is driving the vegetation composition on Buldir Island? • How does the vegetation differ in surface nesting and burrowing seabird colonies?

  7. Surface Nesting Burrowing Seedling trampling Root damage Seabird Vegetation Disturbance Increased soil litter Decreased soil litter Soil compaction Erosion

  8. Surface Nesting Burrowing Seabird Vegetation Disturbance Introduction and expansion of annuals and colonizing plants Increased density Increasing homogenization: Decline of native woody and herbaceous perennials

  9. 55m elev. Surface nester plots Glaucous-winged Gull: “Loafing areas” 5-7 plant species per plot- Changes with elevation Annual Callitriche sp. collected in 2007, in loafing area 246m elev. 196m elev.

  10. Leach’s Storm Petrels Fork-tailed Storm Petrels Cassin’s Auklets Ancient Murrelets ~5 plant species in each plot -changes with slope, nest density Burrow nester plots High Burrow Density Lesser Burrow Density

  11. Asian N.A. N.A. Asian N.A. Asian Aleutian Plant Dispersal“Two Way Filter Bridge” (Carlquist, 1965) Amphi-Pacific Amphi-Pacific Amphi-Pacific Commander Is. (Russia) Buldir Is. Rat Is. (US) Near Is. (US)

  12. Proposed Constraints Distance barrier • Time constraint: • Deglaciation • Eruptions Biotic Constraint: Seabirds as dispersal filters Aleutian Plant Dispersal Asian N.A. Asian N.A. Commander Is. (Russia) Amphi-Pacific Amphi-Pacific Buldir Is. Rat Is. (US) 71 Species not found in Rat Islands (25%) 91 Species not found on Near Islands (29%) Near Is. (US)

  13. Hypothesis- Buldir Island acts as a dispersal filter between the Near and Rat Islands. Near Islands Rat Islands • Species that survive Buldir’s constraints will be dispersed • Near Islands  Rat Islands dispersal is rare

  14. Sorbus sambucifolia Buldir Island Antennariamonocephala

  15. Methods: Phylogenetic Analyses Phylogenetic approaches utilize the relatedness among species to infer assembly processes. Requires: • Knowledge of floral composition • Aphylogenetic “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)

  16. Western Aleutian Islands by Plant # and Island Size Near Islands Rat Islands * Amchitka graminoids added

  17. 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

  18. Future Work • Complete Buldir seabird colony survey & island flora (August 2011) • Complete phylogenetic analyses • More collecting in the Western Aleutians

  19. Western Aleutian Islands • 2010 Survey • First collection of Saxifragaunlaschensis • 226 collections (138 taxa) • Population samples • Therorhodioncamtschaticum • Saxifragafoliolosa 194 205 145 24 142 Near Islands 270 Rat Islands

  20. 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)

  21. 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

  22. Questions?

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