Syndonia Bret-Harte, IAB Univ. Alaska Fairbanks AK 99775 ffmsb@uaf.edu
John Hobbie MBL, Woods Hole, MA 02543 jhobbie@mbl.edu
Jeff Welker Univ. Alaska Anchorage, AK 99508 afjmw1@uaa.alaska.edu
John Yarie Univ. Alaska Fairbanks AK 99775 j.yarie@uaf.edu
This NEON Research Design uses an existing climate and biota gradient in Alaska to address the NEON Science Challenges of 1) developing a predictive model of effects of climate change on ecosystems and their components, and 2) discovering how internal responses and feedbacks of biogeochemistry, biodiversity, hydroecology, and biotic structure and function interact with climate changes.
This research design would enable us to address these challenges in NEON sites along a gradient of climate and biota in Alaska where temperatures have already risen more than two degrees (C) over the past three decades. The annual temperatures range from -10° to +5° C and the annual precipitation from 10 to 470 cm. Vegetation follows the climate from a temperate rain forest in the south through boreal spruce and aspen forests in the interior to tundra in the north. Effects of climate change so far depend greatly on the state of the permafrost that underlies most of Alaska. Where permafrost is thawing, the associated slumping of the soil as embedded ice disappears is having major impacts on commercial infrastructure of homes, roads, and airfields. Lakes are disappearing as their permafrost dams thaw and groundwater movement increases. Farther north, the permafrost is warming but has not yet begun to thaw. Even in these northern sites the chemistry of soil and stream water is changing as increasing depth of the summer thaw exposes soil minerals to weathering. A slow but well-documented change is also occurring as shrubs increase in the tundra and the treeline of spruce moves northward and upward (in the mountains). We expect that changes in biogeochemistry and biotic structure and function already noted in the southern half of the state will begin to be observed throughout the entire state.
The existing knowledge of climate change effects on ecosystems and their components comes from the long-term studies at two LTER sites (Arctic/Toolik, Bonanza Creek/Caribou Poker Creek) as well as short-term observations, past and present, at numerous other sites (e.g., Barrow, Atqasuk, Happy Valley, Dietrich, Nome, Denali, Campbell Creek). Even at the LTER sites, there is no standardization of what is being measured and how. A NEON network offers coordination and standardization of measurement protocols across the network that will provide the opportunity to compare ecosystem response across the gradient. Equally important, NEON will provide long-term data sets at sites where the only data so far came from three-year projects that may or may not continue into the future. Finally, the NEON network will provide intensively-collected data from new locations along the climate and biotic gradient and in this way fill in many of the gaps in our knowledge. For example, there are very few if any data presently being collected along the 580 km of road between Toolik and Bonanza Creek/Caribou Poker Creek LTER sites yet this region includes the transition from boreal forest to tundra. In this proposed Research Design, three new sites (Dietrich, Yukon Mature, Yukon Burn) would be established in this region. In this transition region we will address questions such as: controls on changes in biome distribution, ecotones and the nature of ecotones from an ecosystem perspective-are they abrupt changes in ecosystem properties or gradual; how do changes in ecotones correlate with changes in ecosystem processes?
Partnerships with federal agencies are probable and even necessary for this gradient study. Many of the proposed sites are located on BLM, National Park Service, and US Forest Service land.