Publication Date:
2017-08-15
Description:
The Pantanal is the largest tropical wetland on the planet and yet little information is available on the biome's carbon cycle. We used an automatic station to measure soil CO 2 concentrations and oxidation-reduction potential over the 2014 and 2015 flood cycles of a tree island in the Pantanal that is immune to inundation during the wetland's annual flooding. The soil CO 2 concentration profile was then used to estimate soil CO 2 efflux over the two periods. In 2014, subsurface soil saturation at 0.30 m depth created conditions in that layer that led to CO 2 buildup close to 200,000 ppm and soil oxidation-reduction potential below –300 mV, conditions that were not repeated in 2015 due to annual variability in soil saturation at the site. Mean CO 2 efflux over the 2015 flood cycle was 0.023 ± 0.103 mg CO 2 -C m -2 s -1 representing a total annual efflux of 593 ± 2690 mg CO 2 -C m -2 y -1 . Unlike a nearby tree island site that experiences full inundation during the wet season, here the soil dried quickly following repeated rain events throughout the year which led to the release of soil CO 2 pulses from the soil. This study not only highlights the complexity and heterogeneity in the Pantanal's carbon balance based on differences in topography, flood cycles and vegetation, but also the challenges of applying the gradient-method in the Pantanal due to deviations from steady-state conditions.
Print ISSN:
0148-0227
Topics:
Biology
,
Geosciences
Permalink
