Climate poses a stronger control on litter decomposition than the species or the origin of the litter. That is the main conclusion of our recent paper in Biogeosciences
(on which I collaborated primarily as a statistician).
Getting to know the details about the decomposition of organic matter is a key part in our growing understanding of climate change, as it is a fundamental part of the cycle driving the movement of elements like carbon and nitrogen throughout the ecosystem. The latter is in its turn strong interwoven with the causes and effects of climate change.
- Experimental litter in bags in beech forest in Denmark (These and the next pictures: MPE)
We now proved with data from a large European gradient that the rates at which this plant litter decomposes strongly depends on the climate. Temperature, precipitation and water content of the soil, all of them influenced how much of the litter remained, and which elements to find in the remaining parts.
Pine forest in southern Estonia
This clear correlation is interesting, as it allows us to predict the decomposition with a few parameters that are easy to obtain. Within our diverse set of sites throughout Europe, warmer and wetter climate makes the breakdown go faster. We could then start speculating if this decomposition would also accelerate when the climate gets warmer.
Litter bags distributed on the forest floor
This nice correlation with the climate of course does not replace the role of all kinds of other factors that drive decomposition on a small scale (like mycorrhiza and soil organisms, for example), yet the broad correlations found along the European gradient prove that fast large-scale predictions are definitely possible.
Portillo-Estrada et al. (2016). Climatic controls on leaf litter decomposition across European forests and grasslands revealed by reciprocal litter transplantation experiments. Biogeosciences.