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This dataset consists of pulse-amplitude modulation (PAM) fluorometry data collected using six Micro-PAM (Walz GmbH, Effeltrich, Germany) measurement heads installed on two black spruce trees at the Caribou-Poker Creeks Research Watershed National Ecological Observatory Network (NEON) site (site abbreviation: BONA) near Fairbanks, Alaska. These measurements provide information on the physiological status of photosystem II and photosynthesis more broadly for the needles and trees observed. Three PAM measurement heads were installed on each tree at low, intermediate, and high heights qualitatively within the canopy. Five measurement heads (second intermediate position measurement excluded) were installed in March 2022, with the sixth measurement head being installed in July 2022. Data was collected semi-continuously, including the harsh winter season, until July 2024. PAM fluorescence measurements were collected in a ramped scheme centered around noon to maximize measurement frequency while still allowing for adequate dark acclimation for the nighttime measurement. Saturation pulses were performed by each measuring head every fifteen minutes from 9:00AM – 5:00PM, every thirty minutes from 7:00AM-9:00AM and 5:00PM-7:00PM, and every hour from 2:00AM-7:00AM and 7:00PM-9:00PM. 

This dataset consists of tower-based remote sensing measurements collected using a pair of Fluospec2 (FS2; Yang et al., 2018) instruments, each consisting of two QEPro spectrometers (Ocean Optics, Orlando, USA), installed at the Caribou-Poker Creeks Research Watershed National Ecological Observatory Network (NEON) site (site abbreviation: BONA) near Fairbanks, Alaska. Remote sensing observations include solar-induced fluorescence, derived via a spectral fitting method, near-infrared reflectance of vegetation, and several vegetation indices that can collectively be used to evaluate canopy productivity, photosynthetic phenology, and physiology. Data was collected from two subsites, one FS2 (frequency-synthesizer) instrument installed at each site, located roughly one kilometer apart along a topographic gradient. The evergreen site consists of a black spruce canopy and a lichen and moss understory, with a few larch trees interspersed. The FS2 instrument here was installed on an observation tower (latitude/longitude: 65.15401/-147.50258) installed by NEON that also hosts NEON's meteorological and flux instruments, with the FS2 instrument observing a cluster of black spruce (Picea mariana) trees. At the deciduous site (latitude and longitude: 65.15686833, -147.50367667), a mast was installed within a deciduous canopy consisting of alaskan paper birch (Betula neoalaskana), black spruce, and quaking aspen (Populus tremuloides) trees located roughly one kilometer (km) uphill from the evergreen site. The FS2 instrument installed here observed a paper birch tree located near-nadir from the instrument. Literature Citation: Yang, X., Shi, H., Stovall, A., Guan, K., Miao, G., Zhang, Y., Zhang, Y., Xiao, X., Ryu, Y., & Lee, J. E. (2018). FluoSpec 2—an automated field spectroscopy system to monitor canopy solar-induced fluorescence. Sensors (Switzerland), 18(7). https://doi.org/10.3390/s18072063 

This project aims to gain an improved understanding of the boreal forest carbon balance, including the seasonal contributions of carbon flux (μmol m^-2 s^-1 [micromoles per square meter per second]) and the influence of key environmental conditions (e.g., soil moisture, soil temperature, and vegetation community characteristics) that regulate carbon loss. The dataset includes carbon flux data from chamber-based measurements and the Bonanza Creek National Ecological Observatory Network (BONA NEON) eddy covariance tower, which we gap-filled using a random forest machine learning model. It also includes associated measurements of vegetation (aboveground woody biomass, understory biomass, tree age), radiation (photosynthetically active radiation, leaf area index, air temperature), and soil (moisture, temperature, thaw depth, organic layer depth, bulk density %C [percent carbon], %N [percent nitrogen], C:N [carbon-to-nitrogen ratio], 13C [carbon-13], 14C [carbon-14]), including a soil incubation experiment which measured microbial respiration (mg C / kg soil d [milligrams of carbon per kilogram of soil per day]) under different soil conditions. Chamber-based carbon flux data and their associated measurements (soil moisture, soil temperature, PAR [Photosynthetically Active Radiation], thaw depth) are available May - September 2021 and 2022. In situ sensor data (soil temperature, soil moisture, air temperature, PAR) is available June 2021 - August 2022. Vegetation data and soil samples were collected in July 2022. The gap-filled tower flux data is available from 2019 - 2024. A land cover analysis of the tower footprint is available 2021 - 2022. The study area spans the footprint of the eddy covariance tower, and a 300 m (meters) slopeside lowland-to-upland forest within the Caribou-Poker Creek Research Watershed northeast of Fairbanks, Alaska, described below. 

DVM-DOS-TEM model version used for simulations at Caribou-Poker-Creek Watershed.