Abstract

We have measured the levels of CO₂, CH₄, H₂O vapor, and isoprene in areas within the Coconino National Forest (Arizona, USA) that have been burned by wildfires. Current data is compared with data obtained from the same areas four years prior. Overall, compared to soil gas levels in untouched, pristine forests, soil CO₂ levels were found to be higher in the burned areas. In the case of CH₄, the reverse was true, with levels of CH₄ lower that those found in unburned forest areas. Compared to the same areas studied 4 years prior, greenhouse gas soil concentrations were found to be roughly similar, except for one area in which larger levels of CO₂ and CH₄ were observed. These results may be directly correlated with differences in soil H2O vapor concentration. Here, H₂O levels that are higher may result in greater CO₂ production by soil bacteria, while lower H₂O levels result in higher soil CH₄ relative concentrations. This result is further supported by soil gas measurements taken in the dry season of 2021, prior to the onset of the wet monsoon season. We have also obtained baseline measurements of soil and atmospheric isoprene to use for future comparisons of the levels of forest soil microbial activity.