Understanding drought effects on litter decomposition

Laura Reinelt, Jeanette Whitaker, Elena Kazakou, Laurent Bonnal, Denis Bastianelli, James M. Bullock, Nicholas J. Ostle

This is a plain language summary of a Functional Ecology research article which can be found here.

Droughts will become more frequent and severe with climate change. This can in turn affect ecosystem carbon and nutrient cycling in a way that leads to altered greenhouse gas emissions, creating feedback loops that can potentially further amplify climate change. One puzzle piece to understanding and predicting these feedback loops is to understand the effect of drought on root and shoot litter decomposition.

In our study, we grew three common European grassland species (perennial ryegrass, ribwort plantain and white clover) under droughted and non-droughted conditions in a greenhouse. We then collected the root and shoot litter and conducted a laboratory incubation experiment to compare how quickly the different types of litter decomposed. We also measured traits of the plants, such as leaf and root morphological features and chemical composition, to see if they can explain the differences in decomposition we observed.

Plants of the drought experiment in the greenhouse (left) and laboratory incubation to measure litter decomposition (right, photo credits: Laura Reinelt)

We found that drought strongly affected some morphological and chemical plant traits in all three species, but had much smaller effects on litter decomposition. This is important to know, as results from other studies comparing decomposition between species indicate that plant traits can be used to predict litter decomposition. However, our results suggest traits may not have predictive value in plant communities which have experienced drought. We found that the roots of perennial ryegrass decomposed a little bit faster and the leaves of ribwort plantain decomposed a little bit slower after being subjected to drought. This means that the decomposition of droughted plants could contribute to either positive or negative feedback loops to climate change, depending on the species and the part of the plant. The next step will be to study drought effects on decomposition in more species and under more realistic field conditions.


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