Disturbances are important drivers of the forest carbon (C) cycle. Our knowledge on how changing windthrow
disturbance regimes will affect forest C cycling is, however, far from complete. Here, we investigated the impact
of windthrow on soil respiration (Rs) at mountainous forest sites in the Austrian Alps. Additionally, the effects
of tree regeneration on Rs and decomposition were explored by artificial gap disturbance. Rs did not respond
to windthrow in the initial years after disturbance, but increased above pre-disturbance levels roughly a decade
after windthrow. A temperature related increase in microbial respiration (Rm) offset a decrease in autotrophic soil
respiration (Ra) after windthrow when vegetation re-establishment was scarce. A later increase in Rs was related
to the establishment of a dense grass layer and a consequent increase in Ra. A C loss from increased rates in Rm
was assumed to be the main driver of an observed decline in the soil organic C stocks during the post-windthrow
period. Advance tree regeneration could be shown to slow decomposition and mitigate soil C losses mainly via a
modulation of the soil microclimate. An increasing frequency and severity of windthrow events in mountainous
forest ecosystems could positively feedback on atmospheric CO2 concentrations. However, a pro-active forest
management, which facilitates tree regeneration, could reduce post disturbance soil C losses.
