Intellectual Merit:  The arctic region has warmed significantly over the past 40 years and arctic lands and freshwaters are already changing in response.  The changes include a general “greening” of the arctic landscape, changes in species distributions and abundance, and changes in geophysical and biogeochemical processes and cycles at local and regional scales.  Since 1975, this project and its predecessors have studied these changes by long-term monitoring of tundra and freshwater ecosystems in relation to climate changes, by experimental manipulations of whole tundra, lake, and stream ecosystems, and by comparisons among climatically different sites in northern Alaska and throughout the Arctic.  Increasingly, however, it is apparent that Arctic climate warming is accompanied by dramatic changes in disturbance regime, including the thawing of permafrost, a surprising increase in wildfire, and changes in the seasonality and synchrony of ecosystem processes.  These disturbances, in addition to having major impacts on biogeochemistry, populations, and communities, also lead to major changes in surface energy balance, surface temperatures, water balance, and heat transfer into the permafrost that lies beneath the tundra.  The result is much more dramatic and rapid change in communities and element cycles than is predicted in response to warming alone.  In the long term, warming-related changes in disturbance regime may be more important than the direct effects of warming on arctic tundra and freshwater ecosystems, and on the entire Arctic. 

For these reasons, the overall goal of the Arctic LTER project for 2011-2017 was to understand changes in the arctic system at catchment and landscape scales as the product of: (i) direct effects of climate change on states, processes, and linkages of terrestrial and aquatic ecosystems, and (ii) indirect effects of climate change on ecosystems through a changing disturbance regime. The project addressed these issues in an integrated landscape framework, viewing the Arctic landscape as a spatially linked system including tundra, streams, and lakes. Synthesis of results was further promoted by collocation of terrestrial, stream, lake, and landscape interactions research in the same watersheds and by coordinated sampling of different components of the watersheds.  A mass balance approach to watershed and landscape biogeochemistry was used to develop predictive models and to evaluate results of individual studies in the context of the whole land-water system.  The major products of the research include peer-reviewed publications, a data base, and models that are already proving useful in understanding and predicting long term change in arctic landscape and the interactions and feedbacks between the Arctic and the Globe

Broader Impacts: One key indicator of impact is the number and diversity of citations of Arctic LTER publications. In 2016 we reported over 35,000 citations of the 579 journal publications since 1975 that include contributions from Arctic LTER scientists and collaborators, with an overall h-index of 101. In addition, Arctic LTER scientists had produced 7 books, 95 book chapters, 35 PhD theses, 66 Master's theses, and 15 honor’s theses. The project website is also regularly used as a source of data, with data downloads averaging 5-10 per week.

The Arctic LTER attracts collaborators from all over the world to work at Toolik Lake, make measurements on our long-term manipulations of tundra, streams, and lakes, and make use of our monitoring program and data. Largely because of this leveraging on LTER capabilities, the area around Toolik is the most thoroughly described and studied arctic landscape in the world. Research results from Toolik Lake are often used in comparative studies at other sites. Many of the ideas that drive research in other arctic landscapes were developed from research at Toolik Lake. Examples include the Danish Greenland Ecosystem Monitoring (GEM) programs at Zackenberg and Nuuk, which have continued to call on Arctic LTER personnel for collaboration and advice; the International Tundra Experiment (ITEX) is another example, Examples of impacts outside the Arctic include research to document C losses from surface waters as a component of regional and global C budgets, first pointed out by Kling and colleagues working at Toolik Lake in the 1990s, and the Kuparuk river fertilizer experiment and N isotope experiments, which were the inspiration for the continent-wide STREON experiment.

In education, opportunities for professional training and student research are offered at a variety of levels.  The Arctic LTER maintains an active “Schoolyard Ecology” program in which 2-6 K-12 teachers come to Toolik Lake every summer to work with scientists in the field, leading to improved teaching when they return to their classrooms.  The teachers come from throughout the US, including Alaska.  Arctic LTER also participates most years in the MBL’s Logan Science Journalism program, bringing science journalists to Toolik Lake to work with active scientists in the field.  In addition to graduate student research, 2-6 undergraduates are supported every summer (many via the NSF REU program) to learn research by doing it. 

Last Modified: 05/09/2018
Modified by: Gaius R Shaver