Data from: Proximate controls on semiarid soil greenhouse gas fluxes across 3 million years of soil development

Soils are important sources and sinks of three greenhouse gases (GHGs):
carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, it
is unknown whether semiarid landscapes are important contributors to
global fluxes of these gases, partly because our mechanistic understanding
of soil GHG fluxes is largely derived from more humid ecosystems. We
designed this study with the objective of identifying the important soil
physical and biogeochemical controls on soil GHG fluxes in semiarid soils
by observing seasonal changes in soil GHG fluxes across a three million
year substrate age gradient in northern Arizona. We also manipulated soil
nitrogen (N) and phosphorus availability with 7 years of fertilization and
used regression tree analysis to identify drivers of unfertilized and
fertilized soil GHG fluxes. Similar to humid ecosystems, soil N2O flux was
correlated with changes in N and water availability and soil CO2 efflux
was correlated with changes in water availability and temperature. Soil
CH4 uptake was greatest in relatively colder and wetter soils. While
fertilization had few direct effects on soil CH4 flux, soil nitrate was an
important predictor of soil CH4 uptake in unfertilized soils and soil
ammonium was an important predictor of soil CH4 uptake in fertilized soil.
Like in humid ecosystems, N gas loss via nitrification or denitrification
appears to increase with increases in N and water availability during
ecosystem development. Our results suggest that, with some exceptions, the
drivers of soil GHG fluxes in semiarid ecosystems are often similar to
those observed in more humid ecosystems.