| Summary: | This collaborative project is composed of the following: 0632277 (Oberbauer, Florida International University, LEAD), 0632184 (Welker, UAA), 0632144 (Klein, CSU) and 0632263 (Hollister, GVSU) and will use isotopes and remote sensing to measure phenology, community composition, and ecosystem properties in response to background climate changes and to long-term warming treatments in continuation of work begun under the International Tundra Experiment (ITEX). The overarching goals of this project are to use the sampling power of the ITEX Network to quantify changes in phenology, vegetation, and ecosystem properties that have occurred in tundra over the past 10-15 years in response to climate change and experimental warming, and to use the Network as the foundation for monitoring and prediction of future changes. Among the earliest signals of climate warming in the Arctic have been changes in the seasonal timing of life cycle events (phenology). Plants are leafing, flowering, and fruiting earlier than ever recorded. Because phenology and physiology are tightly coupled, ecosystem functions such as primary production, as well as the outcome of competition depend on phenological responses. Species phenological and physiological responses to warming differ, causing changes in community composition, biodiversity, and ecosystem function. However, in contrast to phenology, change in community composition is difficult to detect and ascribe to a particular phenomenon. Changes in phenology and species abundance being reported across the Arctic are consistent with the findings of the long-term experimental warming of the ITEX network, a plot-scale, nondestructive, warming experiment conducted across the tundra biome beginning in 1990. Remote sensing analyses have also detected earlier greening and increased biomass across polar regions, but cannot readily identify the basis for changes in community composition, can only infer function, and can say nothing about community trajectories. Intellectual merit: The ITEX network was specifically designed to study phenology and community composition, and has also been used effectively to study ecosystem processes. The ITEX network is perfectly positioned for an intensive, comprehensive study of decadal-scale changes in phenology, community composition, and ecosystem function in response to background climate change, and has the added value of long-term experimental warming. The baseline data and sampling power of the ITEX network and its experimental approach are unparalleled. We will compare the results of a renewed field campaign of phenology and plant community composition measurements on warmed and control plots during the IPY with our historical data from 10-15 years ago. The investigators will run two workshops to synthesize the long-term phenological and community changes observed across the network. Furthermore, a new suite of minimally invasive measurements will cross compare indices of ecosystem function - including: leaf, litter, and soil nutrients; isotopic composition; and secondary chemistry - in the control and warmed plots across the network. The long-term nature of these experiments and the global coverage of the coordinated network will lead to unique insights regarding the tundra response to past, ongoing, and future climate changes. Broader Impacts: This study will provide research opportunities and training for two young investigators, a postdoctoral fellow, and graduate, undergraduate, and high school students. The investigators will also actively seek participation of underrepresented residents of the community at Barrow, Alaska, and have incorporated public awareness components about the teleconnections between the Arctic and the Earth System in the communities of Anchorage, AK and Miami, FL. The findings of this work will be published as broadly synthetic works of international interest. Because of teleconnections, findings of this circumpolar project will be of general importance to decision makers. Finally, meetings of the ITEX network will provide a learning experience rich in synthetic understanding of topics from a variety of international and cultural viewpoints. Relevance to IPY: This project meets the goals of the IPY program as an international network with a strong research, networking and outreach components studying effects of warming and climate variability on ecosystems in the Arctic. The ITEX network has been specifically endorsed by the IPY Secretariat as project #188 as demonstrating a high level of adherence to IPY themes and goals. A related endorsement of the Circumarctic Terrestrial Biodiversity (CAT-B) initiative, an offshoot of ITEX, is further evidence of the relevance of this program to IPY. The project will also link with other IPY themes including Back to the Future and The Greening of the Arctic.
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