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Response to Physical Environment -Tundra Robert D. Hollister

Response to Physical Environment -Tundra Robert D. Hollister. What is ITEX?. International Network of experiments Focus on climate change impacts on tundra vegetation of Arctic and Alpine (recently Antarctic) Formalized 1990, earliest sites initiated 1992

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Response to Physical Environment -Tundra Robert D. Hollister

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  1. Response to Physical Environment -Tundra Robert D. Hollister

  2. What is ITEX? • International Network of experiments • Focus on climate change impacts on tundra vegetation of Arctic and Alpine (recently Antarctic) • Formalized 1990, earliest sites initiated 1992 • Primary experiment: passive warming (1-2 ºC) with Open Top Chambers (OTCs), non-destructive measurements. • Networking (16 workshops) • Standard protocols (ITEX manual) • Outputs • Phenology (synth. workshop 1996, publ. 1997, 1999) • Community (synth. workshop 2001, publ. 2005, 2006) • Ecosystem (synth. publ. 2007)

  3. Barrow 13 The original 26 International Tundra Experiment study sites.

  4. Data Collection • Abiotic • Plant • Community • Ecosystem

  5. Abiotic Measures • Screen Height Temperature • Canopy Temperature • Soil Temperature • Precipitation • Canopy Relative Humidity • Soil Moisture • Light Intensity • Wind Speed Near the Ground • Thaw Depth

  6. Plant Measures • Phenology (first visible: leaf, bud, flower, fruit) • Growth(leaf number, leaf length) • Reproduction(number and size of flowers)

  7. Luzula confusa 25 AD 20 AW BD Inflorescence length (cm) BW 15 10 1998 1999 2000 5 0 160 180 200 220 Julian day 25 20 Inflorescence length (cm) 15 10 5 0 0 200 400 600 TDDsm Symbol - site Line - year Fill/Color - treatment control warmed

  8. Atqasuk Wet Meadow Warmed (OTC) plot • Community Measures • Species Composition (measured using a point frame):

  9. Atqasuk Dry Heath Warmed (OTC) plot • Ecosystem Measures • Carbon Exchange(measured using a LiCOR) • Nutrient Changes (soil samples and resin membranes)

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