Desert plants also have their limits.
As arid ecosystems experience more intense heat waves and droughts, scientists have wondered how climate change could affect the hardy plants that thrive in harsh deserts or arid mountains.
With around 40% of the earth covered with dry land, the question is of enormous importance for nature conservation policy: Are these plants prepared for even more extreme conditions by their natural resistance? Or have you already reached the limits of your resilience?
Recent research suggests that arid areas are at a breaking point – and this is more closely tied to temperature than previously thought.
Dryland ecosystems “may be more vulnerable to climate change than expected,” wrote researchers from a group at the University of California at Irvine in a recent study around the Anza-Borrego Desert State Park near the Mexican border.
“Our analysis suggests that these ecosystems may have crossed an ecological threshold,” they said, describing a breakdown in the relationship between precipitation and vegetation cover from around 1999.
In the Sonoran Desert and adjacent landscapes, the scientists found, the vegetation cover was shrinking much more than drought or forest fires alone could explain. Satellite observations between 1984 and 2017 showed “widespread” declines in perennial vegetation cover, the researchers wrote, particularly in lowland deserts.
In the lowlands, the modeling found that temperature explains much of the desert vegetation change, according to the study. Rising heat was the best long-term explanation for the decline in vegetation, as rainfall and forest fires varied wildly from year to year.
The importance of warmth surprised even the researchers.
“Many plant species in desert ecosystems have adaptations that allow them to withstand high temperatures, which makes this observation somewhat unexpected,” they wrote.
More research is needed to explain the mechanism behind this relationship, the authors added. One possible reason is that in hot weather, water evaporates faster, causing even worse water stress for plants in the hot summer months.
The effects of the research could be devastating.
Drought conditions have resulted in mass plant deaths in Southern California. This has changed the way the ecosystem reacts to climate change, the researchers write. In particular, it appears to have broken the once predictable relationship between rain and vegetation cover.
“One potential implication is that it will be very difficult to predict future responses to changing environmental conditions. This could be an important constraint on our ability to understand how arid areas will be affected by future climate change, ”they wrote.
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides important news for energy and environmental professionals.