Potential Bias Of Daily Soil Co2 Efflux Estimates Due To Sampling Time

  • Sites: MX-EMg
  • Cueva, A., Bullock, S. H., López-Reyes, E., Vargas, R. (2017/12) Potential Bias Of Daily Soil Co2 Efflux Estimates Due To Sampling Time, Scientific Reports, 7(1), . https://doi.org/10.1038/s41598-017-11849-y
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  • Soil respiration (Rs) has been usually measured during daylight hours using manual chambers. This approach assumes that measurements made during a typical time interval (e.g., 9 to 11 am) represent the mean daily value; locally, this may not always be correct and could result in systematic bias of daily and annual Rs budgets. We propose a simple method, based on the temporal stability concept, to determine the most appropriate time of the day for manual measurements to capture a representative mean daily Rs value. We introduce a correction factor to adjust for biases due to non-optimally timed sampling. This approach was tested in a semiarid shrubland using 24 hr campaigns using two treatments: trenched plots and plots with shrubs. In general, we found optimum times were at night and potential biases ranged from −29 to + 40% in relation to the 24 hr mean of Rs, especially in trenched plots. The degree of bias varied between treatments and seasons, having a greater influence during the wet season when efflux was high than during the dry season when efflux was low. This study proposes a framework for improving local Rs estimates that informs how to decrease temporal uncertainties in upscaling to the annual total.

  • https://www.nature.com/articles/s41598-017-11849-y