Data from: Drought disrupts atmospheric carbon uptake in a Mediterranean saline lake

Saline inland lakes play a key role in the global carbon cycle, acting as
dynamic zones for atmospheric carbon exchange and storage. Given the
global decline of saline lakes and the expected increase of periods of
drought in a climate change scenario, changes in their potential capacity
to uptake or emit atmospheric carbon are expected. Here, we conducted
continuous measurements of CO2 and CH4 fluxes at the ecosystem scale in a
saline endorheic lake of the Mediterranean region over nearly 2 years. Our
focus was on determining net CO2 and CH4 exchanges with the atmosphere
under both dry and flooded conditions, using the eddy covariance (EC)
method. We coupled greenhouse gas flux measurements with water storage and
analyzed meteorological variables like air temperature and radiation,
known to influence carbon fluxes in lakes. This extensive data integration
enabled the projection of the net carbon flux over time, accounting for
both dry and wet periods on an interannual scale. We found that the system
acts as a significant carbon sink by atmospheric CO2 uptake in
wet conditions, with uptake ceasing in periods of drought. Moreover,
increased air temperatures during wet phases slightly decrease the CO2
uptake efficiency. Regarding CH4, we measured uptake rates that exceeded
those of well-aerated soils such as forest soils or grasslands.
Additionally, we observed that CH4 uptake during dry periods was nearly
double that of wet periods. However, the absence of continuous data
prevented us from correlating CH4 uptake processes with potential
environmental predictors. Our study challenges the widespread notion that
wetlands are universally greenhouse gas emitters, highlighting the
significant role that endorheic saline lakes can play as natural sink of
atmospheric carbon. However, our work also underscores the vulnerability
of these ecosystem services in the current climate change scenario, where
drought episodes are expected to become more frequent and intense in the
coming years.