An international team of researchers from different institutions has identified the biological mechanism that causes death to tropical trees when they suffer the effects of a prolonged drought. Until now, the most widespread hypothesis among experts was that the absence of water prevented plants from manufacturing the sugars necessary for their metabolism to function properly . This is, in essence, an intense drought could end them due to lack of nutrients.
In a recent essay published in the journal Nature , these scientists point out that, in reality, the amount of water available does not affect the ability of trees to store sugars . In fact, after studying the behavior of the tallest species that cover the Amazon basin for 13 years, they observed that it was the same regardless of whether there was rain or not. However, they found that when a severe drought occurred, air bubbles formed in the sap, preventing the water from flowing properly through the plant tissues.
Likewise, these ecologists, coordinated by Lucy Rowland, from the Faculty of Geosciences at the University of Edinburgh, found that the most vulnerable trees were the tallest, while the smallest had the best chance of survival.
Some climate models argue that in the coming decades rainfall will decrease in many tropical areas, so, they indicate, this phenomenon could significantly affect the amount of carbon dioxide that reaches the atmosphere. And, on the one hand, smaller species store less carbon than larger ones ; on the other, dead specimens that decompose contribute to more CO2 being produced.
