According to Ralph Waldo Emerson, nature is no spendthrift. Alas, he was wrong.
Biologists from the University of Utah including William Anderegg, Anna Trugman, and David Bowling have led new research and discovered that some trees and plants are prolific spendthrifts in drought conditions, "spending" precious soil water to cool themselves and, in the process, making droughts more intense. The researchers published their findings in Proceedings of the National Academy of Sciences.
Anderegg explained that they show that the actual physiology of the plant matters. How trees take up, transport, and evaporate water, can influence societally essential extreme events, like severe droughts that can affect people and cities.
In his research, Anderegg examined how tree traits affect how well forests can handle hot and dry conditions. He discovered that some trees and plants possess an internal plumbing system that slows down the movement of water, helping the plants to minimize water loss during the hot and dry periods. However, other plants have a system more suited for transporting large quantities of water vapor into the air, larger openings on leaves, more capacity to move water within the organism. Past works on Anderegg have been based on how those traits determine how well trees and forests can weather droughts. This new research, however, asks a different question: how do those traits affect the drought itself?
Explaining, Anderegg noted that they have known for a long time that plants can affect the atmosphere and can affect weather. Forests and plants draw water out of the soil and exhale it into the atmosphere, changing the balance of water and heat at the surface of the planet, which fundamentally controls the weather. In some cases, like the Amazon rainforest, all of that water vapor could jumpstart precipitation. Even deforestation can affect weather downwind by leaving regions drier than before.
Hot and dry regions, as it's been in the convention, tend to have more plants and trees that are adapted to dry conditions. Regardless of the climate, however, some species with water-intensive traits such as oaks in a Mediterranean climate can still exacerbate a drought.
Understanding the relationship between a tree's traits and drought conditions helps climate scientists and local leaders to plan for further drought effects on communities, according to Anderegg. He said that failing to account for this crucial physiology of plants would give them less accurate predictions for what climate change is going to mean for drought in a lot of regions.
Always in Anderegg's mind is drought and even during the recent wet spring, he noted that just because there is a good water year in the U.S. and Utah this year doesn't get off the hook. It is good to remember that there is going to be a lot more droughts in the future.
