Drivers of Decadal Carbon Fluxes Across Temperate Ecosystems.
Ankur R Desai, Bailey A Murphy, Susanne Wiesner, Jonathan Thom, Brian J Butterworth, Nikaan Koupaei-Abyazani, Andi Muttaqin, Sreenath Paleri, Ammara Talib, Jess Turner, James Mineau, Aronne Merrelli, Paul Stoy, Ken Davis
Author Information
Ankur R Desai: Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison WI USA. ORCID
Bailey A Murphy: Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison WI USA. ORCID
Susanne Wiesner: Department of Plant and Earth Science University of Wisconsin-River Falls River Falls WI USA. ORCID
Jonathan Thom: Space Science and Engineering Center University of Wisconsin-Madison Madison WI USA. ORCID
Brian J Butterworth: Cooperative Institute for Research in Environmental Sciences CU Boulder Boulder CO USA. ORCID
Nikaan Koupaei-Abyazani: Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison WI USA. ORCID
Andi Muttaqin: Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison WI USA. ORCID
Sreenath Paleri: Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison WI USA. ORCID
Ammara Talib: Department of Civil and Environmental Engineering University of Wisconsin-Madison Madison WI USA. ORCID
Jess Turner: Freshwater & Marine Sciences University of Wisconsin-Madison Madison WI USA. ORCID
James Mineau: Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison WI USA. ORCID
Aronne Merrelli: Department of Climate and Space Sciences and Engineering University of Michigan Ann Arbor MI USA. ORCID
Paul Stoy: Department of Plant and Earth Science University of Wisconsin-River Falls River Falls WI USA. ORCID
Ken Davis: Department of Meteorology Pennsylvania State University University Park PA USA. ORCID
Long-running eddy covariance flux towers provide insights into how the terrestrial carbon cycle operates over multiple timescales. Here, we evaluated variation in net ecosystem exchange (NEE) of carbon dioxide (CO) across the Chequamegon Ecosystem-Atmosphere Study AmeriFlux core site cluster in the upper Great Lakes region of the USA from 1997 to 2020. The tower network included two mature hardwood forests with differing management regimes (US-WCr and US-Syv), two fen wetlands with varying levels of canopy sheltering and vegetation (US-Los and US-ALQ), and a very tall (400 m) landscape-level tower (US-PFa). Together, they provided over 70 site-years of observations. The 19-tower Chequamegon Heterogenous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors 2019 campaign centered around US-PFa provided additional information on the spatial variation of NEE. Decadal variability was present in all long-term sites, but cross-site coherence in interannual NEE in the earlier part of the record became weaker with time as non-climatic factors such as local disturbances likely dominated flux time series. Average decadal NEE at the tall tower transitioned from carbon source to sink to near neutral over 24 years. Respiration had a greater effect than photosynthesis on driving variations in NEE at all sites. Declining snowfall offset potential increases in assimilation from warmer springs, as less-insulated soils delayed start of spring green-up. Higher CO increased maximum net assimilation parameters but not total gross primary productivity. Stand-scale sites were larger net sinks than the landscape tower. Clustered, long-term carbon flux observations provide value for understanding the diverse links between carbon and climate and the challenges of upscaling these responses across space.
