Impacts of drought on grassland production and SOC stocks in a future climate

Severe droughts are expected to become more frequent in a future climate.

Water availability controls crop growth, which in turn has direct and indirect effects on flows of energy, water, carbon (C), and nutrients in the soil-plant system.

For grasslands, there are indications that drought may alter the partitioning of above- and below-ground production, with more C being allocated to the root system. Microbial carbon use efficiency (CUE) may also change in a warmer climate. The amount of root-derived C that can be stored in the soil therefor difficult to predict in a future climate climate.

Soil C models assume that the C supply from plants is a fixed input unaffected by climate.

On the other hand, the  interactions between soil water dynamics and plant growth in existing crop models are generally poorly described, although they have a significant impact on C dynamics.

In this four-year project, we will develop a new model that will account for dynamic feedbacks between soil hydrology, plant growth, and microbial activity.

It will be tested against data from the Tereno-SoilCan lysimeter network in Germany and a field experiment in Sweden with grass subjected to drought and control treatments.