Methane from soil released by trees
Methane (CH4) is a rather more potent greenhouse gas than carbon dioxide, although it’s less famous simply because there’s much less of it. So it was a surprise when, a few years ago, some scientists claimed that plants release methane, actually contributing to global warming.
The work people have done since then shows that plants probably don’t make methane themselves, so they’re off the hook there. But a recently released study suggests that they can release it from the soil.
When there’s no oxygen in the soil, for example in flooded land, certain microbes make methane. Chemically, their metabolism is reducing, rather than oxidising, like our own. In fact, that sort of life was the norm for perhaps the first billion years of life on earth. Then photosynthesis (by algae, this was long before plants) produced enough oxygen to tip the atmosphere from reducing to oxidising, and ever since, reducing life has been stuck in flooded soils, animals’ guts, and so on, while all us oxidisers grow, run, fly or swim free.
Rice, A. L., C. L. Butenhoff, M. J. Shearer, D. Teama, T. N. Rosenstiel, and M. A. K. Khalil (2010), Emissions of anaerobically produced methane by trees, Geophys. Res. Lett., 37, L03807, doi:10.1029/2009GL041565.