Trees use water more efficiently due to climate change

An international investigation, in which the Center for Ecological Research and Forestry Applications of the Autonomous University of Barcelona (CREAF-UAB) has participated, has shown that trees and forests are "learning" to adapt to climate change and make more use of efficient water they receive.

The study, published in the PNAS magazine, has revealed that forests have adjusted their way of growing in the face of climate change, taking advantage only of the fertilizing effect of carbon dioxide, and thus grow faster if water is abundant.

Trees have increased water use efficiency in recent decades and they are adjusting the way they grow to climate change. If the water is more abundant, they grow faster and if it is scarce, they photosynthesise at high speed and save it.

The study suggests that plants' water-use efficiency has increased in recent decades, as with more carbon available in the atmosphere they could photosynthesize more quickly and save water.

The research, led by the University of New Hampshire (United States), has found that the relationship is not as direct or simple as it seemed, but that the trees "have learned" to act in the face of the increase in CO2 in one way or another it is depending on the availability of water.

“If water is abundant, they do increase carbon dioxide capture and photosynthesize faster to grow without taking transpiration into account; On the other hand, if water is scarce, they prefer to slow down and conserve it”, explained the author of the article and CREAF ecologist, Rossella Guerrieri.

Growth rings

The results have been obtained thanks to the analysis of 12 different species of trees in the USA. "We have chosen eight mature forests and for each species of tree, we have extracted a piece of wood from its trunk. Once the rings that corresponded to the last 30 years of growth have been identified, we have applied a chemical analysis technique to them”, Guerrieri detailed.

"This procedure -he added- is done with isotopes and it is the only one that allows us to imagine how trees have responded to the increase in atmospheric dioxide and changes in climate over the last decades."

The ecologist has specified that plants use pores in their leaves, known as stomata, to exchange gases from the atmosphere, and regulate their temperature and the water they have absorbed. During photosynthesis, through these pores, they absorb the carbon dioxide they need to feed and grow, "but at the same time, however, these little holes lose water."

"To find out if a plant is efficient or not, we look at how much it grows relative to how much water it uses to grow," biologist Scott Ollinger has reported. “It is the same as the kilometres per litre of gasoline in a car, but with tons of carbon per litre of water”, he has compared.

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