Data from: Increased belowground carbon allocation reduces soil carbon losses under long-term warming

The response of the carbon cycle in forests to global warming could lead
to a positive climate feedback if warming accelerates the mineralization
of soil organic carbon (SOC), thereby causing net emissions of CO2 into
the atmosphere. In Europe, humus-rich alpine forest soils could be
particularly affected by global warming, as a greater rise in temperature
is expected in this region than the global average. Here we show that
nearly two decades of experimental soil warming (+4°C during the snow-free
seasons) in a mountain forest in the Northern Limestone Alps significantly
(13% per 1°C warming) and persistently (no change in response over 18
years) increased soil CO2 effluxes. The SOC stocks in the warmed plots
decreased compared to controls, yet non-significantly, and quantitatively
much less than the surplus carbon outflux from warmed soil suggests. We
attribute the increase in soil CO2 efflux primarily to stimulation of root
respiration, which was most sensitive to long-term warming.