| Summary: | 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) and the influence of key environmental conditions (e.g., soil moisture, soil temperature, and vegetation community characteristics) that regulate carbon loss. This dataset includes chamber-based carbon dioxide (CO2) and methane (CH4) fluxes and environmental variables along a 300m slopeside lowland-to-upland forest transect within the Caribou-Poker Creek Research Watershed northeast of Fairbanks, Alaska. The transect spans lower-hillslope black spruce (Picea mariana), mid-slope white spruce (Picea glauca ) and upper-slope deciduous (Betula neoalaskana, Populus tremuloides) dominated tree stands. Two closed chambers, attached to a portable LICOR LI-7810 gas analyzer, were used to measure CO2 and CH4 fluxes at collars along the transect. Soil respiration (including autotrophic respiration from roots, and microbial respiration) was measured at 21 collars where aboveground vegetation had been clipped and removed prior to the study, using a pressure, temperature, and humidity controlled LI-COR Smart Chamber. We also used an acrylic clear chamber at 10 locations over intact ecosystems (i.e., where vegetation was not removed) along the transect to measure net ecosystem CO2 and CH4 exchange and net ecosystem emission (e.g,. clear chamber was covered to create no-light conditions, preventing carbon uptake through photosynthesis). The dataset also contains environmental variables that may be correlated with carbon flux. These include soil moisture (m^3 m^-3), soil temperature (°C), thaw depth (cm), and photosynthetically active radiation (PAR, μmol m^-2 s^-1) along the transect. Sensor arrays at each end of the transect collected soil moisture and soil temperature at 20cm and 40cm depth, as well as PAR and air temperature (°C). Analysis of these data can help determine which environmental variables are controls of soil respiration and photosynthetic uptake. Smart Chamber data are available weekly May-September 2021 and every other week May-August 2022. Clear chamber date are available weekly July-August 2022. Sensor array data are available June 2021-August 2022 with some gaps.
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