LTER: The Role of Climate Variability in Controlling Arctic Ecosystem Function

DESCRIPTION: The Arctic is warming more rapidly than the rest of the planet. Thawing of previously frozen soils will have consequences for society through alteration of carbon emissions. Most previous research has focused on how Arctic ecosystems respond to average warming trends. There is however very little research on variability of environmental conditions within that average warming trend. The Arctic Long-Term Ecological Research site (ARC-LTER) community has found that tundra ecosystems respond strongly to fluctuations in environment on a range of time scales. ARC-LTER will continue to produce long-term data and perform modeling simulations that examine the role of that environmental variability on critical ecosystem functions. The main activities in this renewal will expand our understanding by focusing on how climate variability affects the terrestrial production and breakdown of organic matter and how those processes combine to affect CO2 production in lakes and streams. The project will therefore contribute understanding of how trends in mean climate, climate variability, and disturbances all interact to control arctic ecosystem structure and function. The project will have many broader impacts such as training of young investigators, engagement of K-12 teachers in research via the Earth Camp program, schoolyard activities and research experiences for teachers. Outreach to stakeholders will include briefings to Alaska State, North Slope Borough, and US government agencies overseeing environmental and natural resource programs. ARC-LTER will also work with the Study of Environmental Arctic Change program on co-production of knowledge with Indigenous experts for use in decision making. The 2023-2029 ARC-LTER project will determine how concurrence of climate trends and altered variability of environmental conditions combine to affect arctic ecosystems. The project will test the hypothesis that variability in environmental conditions is a stronger driver of change in the Arctic than are the average long-term trends in climate. The project will examine how ?openness? and ?connectedness? of ecosystems relate to disturbances such as wildfire and climate change. This research will include the maintenance of ongoing and development of new activities associated with long-term monitoring, experiments and numerical modeling work in the vicinity of Toolik Lake, AK. The project will address three main questions which will integrate research along the terrestrial-aquatic continuum: Question 1: How does climate variability affect the openness and connectivity of arctic ecosystems? This research will focus on vegetation and biogeochemical cycles in moist acidic tundra along an existing nutrient gradient, within warming plots, and in nearby Alder stands. Question 2: How does climate variability affect key consumers and their influence on ecosystems? The research activities will focus on how climate variability affects the composition of consumer communities, their influence on ecosystems, and the genomic potential and metabolism of microbial communities. Question 3: How does climate variability affect carbon dynamics along the terrestrial-aquatic continuum? The project will study how the dynamics of carbon biogeochemistry along the continuum are affected by environmental variability. Together, the answers to these questions will improve our understanding on how long and short-term changes in environment shape ecosystem function.

BROADER IMPACTS: ARC-LTER research has broad impacts on science with over 68,000 citations of the 730 journal publications by our researchers and collaborators since 1975. The 145 publications since 2017 have been cited 2,660+ times. This impact will grow with new publications from ongoing long-term and proposed research. Associated researchers, postdocs, and students benefit from access to long-term data and the ability to conduct complementary studies in our monitoring and experimental sites. This approach will maintain a pipeline of support for the many excellent assistant and associate researchers now affiliated with the project. Education and outreach to non-scientists will be expanded, and a new ARC-DEI plan guides our efforts to broaden diversity and participation in all our activities. These activities include: (i) engagement of K-12 teachers in summer research programs via our Schoolyard program, Earth Camp, NSF RET, and NSF PolarTREC efforts, (ii) support, mentoring, and inclusion of undergraduates (including two REUs) and graduate students associated with ARC, (iii) briefings to Alaska State, North Slope Borough, and US government agencies overseeing environmental and natural resource programs, (iv) collaboration with the NSF SEARCH program co-producing knowledge with Indigenous experts for use in decision making, (v) engaging learners in analysis of ARC data by producing education modules, and (vi) graduate student participation in workshops, LTER all-scientist meetings, and in an open, annual ARC-LTER meeting.