Depth profiles of soil CO2 Concentrations, soil temperature, and soil moisture (Rocky Mountain Biological Laboratory, Gothic, Colorado, 2011-2016)

Soil respiration (the flux of CO2 from the soil surface) is one of the largest and most variable fluxes in the global carbon cycle, and yet also one of the least understood, primarily due to methodological difficulties. These are (1) measuring soil respiration at high temporal frequencies and (2) attributing flux variations to its functionally different sources, plants and microbes. In 2009, we installed vertical profiles of automated soil pore space CO2 concentration sensors (Vaisala GMM 222; 5-sensor profile) under two forest cover types (deciduous aspen and evergreen spruce) at the Rocky Mountain Biological Laboratory (RMBL) in Gothic, Coloardo. These sensors are advantageous for the RMBL ecosystem because they have no moving parts, and thus can make measurements throughout the winter and underneath the snowpack. The CO2 profile measurements are paired with soil temperature and moisture measurements. The CO2 concentration sensors were recalibrated in 2018. The concentration data can be converted to estimates of soil CO2 production using a 1-D gas diffusion model. The profile information allows us to spatially separate soil CO2 production within the soil profile, and to assess how soil respiration responds to varying environmental conditions in the different vegetation communities. The datasets (.csv format) contain the following variables: Year — YYYY Month — MM Day — DD Hour — HH Day of Year — DOY Fraction of Year — YYYY+DOY/366 CO2 50cm — Soil CO2 concentration @ -50 cm depth (ppm) (Vaisala) CO2 15cm — Soil CO2 concentration @ -15 cm depth (ppm) (Vaisala) CO2 5cm — Soil CO2 concentration @ -05cm depth (ppm) (Vaisala) CO2 0cm — Soil CO2 concentration @ soil surface (ppm) (Vaisala) CO2 1.5m air — Ambient air CO2 concentration @ 150 cm above soil surface (ppm) Soil T 50cm — Soil temperature @ -50 cm depth (°C) Soil T 15cm — Soil temperature @ -15 cm depth (°C) Soil T 5cm — Soil temperature @ -05cm depth (°C) Soil T 0cm — Soil temperature @ soil surface (°C) T 1.5 air — Air temperature @ 150 cm above soil surface (°C) VWC 50cm — Soil volumetric water content @ -50 cm depth (%) (Campbell) VWC 15cm — Soil volumetric water content @ -15 cm depth (%) (Campbell) VWC 5cm — Soil volumetric water content @ -05cm depth (%) (Campbell) Decagon Soil T 50cm — Soil temperature @ -50 cm depth (°C) (Decagon) Decagon Soil T 15cm — Soil temperature @ -15 cm depth (°C) (Decagon) Decagon Soil T 5cm — Soil temperature @ -05cm depth (°C) (Decagon)