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What is ITEX?

Collaborative Research: Study of Arctic ecosystem changes in the IPY using the International Tundra Experiment (ITEX). Steve Oberbauer, Robert Hollister*, Jeff Welker, Julia Klein, William Gould, Patrick Sullivan, Bartmar Sveinbjornsson, Keith Boggs, & Caroline Lewis. What is ITEX?.

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What is ITEX?

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  1. Collaborative Research:Study of Arctic ecosystem changes in the IPY using the International Tundra Experiment (ITEX) Steve Oberbauer, Robert Hollister*,Jeff Welker, Julia Klein, William Gould, Patrick Sullivan, Bartmar Sveinbjornsson, Keith Boggs, & Caroline Lewis

  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. ITEX sites directly and collaboratively involved with this project (Southern Australian and Switzerland sites not shown).

  4. 1 Thule, Greenland • 2 Barrow, Alaska • 3 Atqasuk, Alaska • 4 Toolik, Alaska • 5 Tibetan Plateau, China • 6 Niwot Ridge, Colorado

  5. Project components • Phenological Change (weekly, 2007, 2008) • Compare control vs. warmed, current vs. past • Remeasurement of first green leaf, flowering & seed set and progression of growth & reproductive effort • Community Change (once peak season, 2007 or 08 ) • Compare control vs. warmed, current vs. past • Remeasurement of ITEX plots and km2 grids at Toolik & Imnavait Creek using point framing • Ecosystem change (once peak season, 2007 or 08 ) • Compare control vs. warmed • Reflectance measurements of cover/biomass (NDVI) and photosynthetic physiology (PRI) • Leaf, litter, and soil nutrients • Leaf and litter isotopes (13C, 15N, 18O) • Leaf secondary compounds (tannins and lignins) • Radiocarbon of soil respiration (age of carbon leaving soil)

  6. Synthesis workshops • Phenological change 2008 • Community change 2009

  7. Data management • Data collection: all non real-time • Limited sites-weekly: plant phenology, plot reflectance • Cross sites-peak season: reflectance; point-quadrat plot canopy structure and composition; nutrients and isotopes of leaves, litter, and soil; leaf tannins and lignins; respiratory and soil radiocarbon • Data Screening: Data double checked/ outlier/visualization screening • Metadata: JOSS format • Data archiving: NSIDC

  8. Major results • OTC approach validated with natural climate variation • Phenology changes with small temperature increase • Controls are changing with background • Community changes toward taller, shrubbier with warming • Wet sites accumulate carbon, dry sites release carbon with warming

  9. The value of ITEX for IPY • Stable network, broad international coverage • Long-term data 10-15 years for some. • Experimental changes • Changes on Controls • Detailed vegetation analysis • Ecosystem • Nondestructive (repeated measures)

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