Floods may be nearly as important as droughts for future carbon accounting

 Stanford University researchers found that photosynthesis -was primarily influenced by floods and heavy rainfall nearly as often as droughts in many locations

In a global analysis of vegetation over more than three decades, Stanford University researchers found that photosynthesis -- the process by which plants take up carbon dioxide from the atmosphere- was primarily influenced by floods and heavy rainfall nearly as often as droughts in many locations.

The paper, published in the journal Environmental Research Letters, highlights the importance of incorporating plant responses to heavy rainfall in modeling vegetation dynamics and soil carbon storage in a warming world.

"These wet extremes have basically been ignored in this field and we're showing that researchers need to rethink it when designing schemes for future carbon accounting," said senior study author Alexandra Konings, an assistant professor of Earth system science in Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "Specific regions might be much more important for flood impacts than previously thought."

More photosynthesis in combination with other factors can enable greater amounts of carbon to be stored in the soil over the long term, according to the researchers. To estimate the presence of photosynthesis, they analyzed plant greenness according to publicly available satellite data from 1981 to 2015.

Because the field of carbon accounting is dominated by research on drought impacts, the co-authors were surprised to find that photosynthesis was affected by flooding so frequently- in about half the regions in the analysis. While drought is known to decrease photosynthesis, wet extremes can either decrease or accelerate the process.