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Keywords:

  • Atlantic Canada;
  • forced diffusion chambers;
  • high-frequency data set;
  • soil CO2 efflux

Summary

1. A better understanding of temporal and spatial variability of soil CO2 fluxes is essential to improve model predictions of soil effluxes. To accomplish that goal, high-frequency and long-term data sets for model development and validation are needed. However, the cost and high maintenance associated with the current technology make high-frequency measurements for small or large spatially distributed grids difficult to achieve. Here, we describe a new observational infrastructure for monitoring soil CO2 efflux, which is attractive because of its low cost and low power consumption compared to traditional methods.

2. Three observational stations equipped with forced diffusion (FD) chambers were deployed in the summer of 2010 across a 1000-km transect in Atlantic Canada. At half-hourly resolution, each observational station recorded soil carbon dioxide (CO2) efflux from two flux chambers and from a suite of meteorological sensors and peripherals. Each station was equipped with telemetry, and data were continuously downloaded for c. 1 year.

3. The average power consumption for each station was roughly a third of a LI-COR LI-8100 system. The FD chambers were approximately four times more affordable than conventional equipment and were also reliable with <1% of the data lost because of power failure.

4. High-frequency observations from the three sites showed that the systems were extremely dynamic, with CO2 efflux dependency to temperature and moisture on many time-scales. For instance, the data showed pronounced increases in soil CO2 efflux after major rain events. The results from the FD chambers also highlighted the role of other biological and physical factors on soil CO2 efflux.

5. Overall, this new method was very successful in key areas including survivability, management intensity and cost. The high-frequency data hold many interesting features that are not captured in synoptic data sets and which will be useful for tuning our understanding of soil carbon dynamics.