View article

Changes in land‐use and climate are likely to alter moisture and substrate availability in tropical forest soils, but quantitative assessment of the role of resource constraints as regulators of soil trace gas fluxes is rather limited. The primary objective of this study was to quantify the effects of moisture and substrate availability on soil trace gas fluxes in an Amazonian regrowth forest. We measured the efflux of carbon dioxide (CO₂), nitric oxide (NO), nitrous oxide (N₂O), and methane (CH₄) from soil in response to two experimental manipulations. In the first, we increased soil moisture availability during the dry season by irrigation; in the second, we decreased substrate availability by continuous removal of aboveground litter. In the absence of irrigation, soil CO₂ efflux decreased during the dry season while irrigation maintained soil CO₂ efflux levels similar to the wet season. Large variations in soil CO₂ efflux consistent …