The extensive storage of organic C in forest soils relies on the relatively slow turnover of this carbon pool. However, changes in water availability due to changing precipitation patterns may alter the rate of micorbial soil organic matter degradation and thus lead to shorter organic carbon turnover time and a positive feedback, which may even accelerate climate change.
In this work we present the findings from a three year drought elimination experiment in Yatir forest, a pine forest planted in the semi-arid region of Israel. The measured soil C fluxes under trees and between trees are compared with those in a non-irrigated plot, to try and elucidate the effect of soil moisture availability on soil C processes. The effects of drought elimination on soil C emission following re-wetting are highlighted.
In addition measurements of the soil organic C pools six years after irrigation commenced and the partitioning between a stable soil organic C pool (associated with soil minerals) as compared to a labile organic C pool are discussed. The integration of the soil fluxes and pools is used to elucidate major mechanisms expected to take place in a changing climate.