Plants are having a hard time on an ever-warming planet. Not only do high temperatures make survival more difficult, but dehydration also causes problems. The question that has been preoccupying climate scientists for some time is: Which plants are more resistant to dry soil or dry air?
The question is complicated because we know much more about warming than its effect on soil moisture, plus plants are smarter than you think. They can adapt to a bone-dry environment. It’s important to know more about this so we can ensure as many plants as possible survive the climate crisis.
So scientists from Harvard University investigated a very special place in this case, the salt flats of Utah and Nevada, where no plants grow at all. They looked at the defense mechanism of plants. In doing so, they close the tiny pores on their leaves, called stomata, to limit photosynthesis and retain water. It turns out that this mechanism works better with dry ground than with dry air.
This is great, because Previous search He showed that it was the opposite. Plants close their stomata in dry air. But the researchers immediately believed that these results did not tell the full story of plants’ vulnerability to the dry environment.
There is no causal relationship
According to researchers, a phenomenon known to science played a role. “The problem with this interpretation is that correlation does not mean causation,” says lead researcher Caegen McCall. “If plants close their stomata, it can cause the air to become dry, rather than the other way around.”
A bold hypothesis, which would also require a bold research site. Why look for plants to survive in a place where nothing grows? The answer: Because the salt flats of the American desert are one of the few places on Earth where there is a strong water cycle, but there is no vegetation.
I’m looking for another explanation
Then the researchers started calculating. Using data from the deserts of Nevada and Utah, they reproduced previous studies that showed the relationship between air dryness and the movement of moisture, in this case through evaporation from the Earth’s surface, and attributed the numbers to plants closing their stomata to retain water.
The Harvard team discovered something special: Their calculations matched the results of previous studies almost perfectly, but… there were no plants at all on the salt flats. So there had to be another explanation.
There is no consensus
Evaporation in this plant-free environment responds only to the degree of dryness of the soil. Therefore, the response of plants to moisture deficiency may have been overestimated in previous studies. The researchers believe that plants respond mainly to dry soil, a stress factor known to reduce photosynthesis.
The conclusion then is that soil dryness has a greater impact on plant ecosystems than air dryness. This could have consequences for global climate policy. “Our findings confirm expectations regarding water for the future,” says researcher Vargas Zepitello. “People talk about consensus on climate change, but this is primarily about global temperatures. There is much less consensus about what regional changes in the water cycle will look like. It is important that we gain more knowledge about this, so that we can better understand Preserving ecosystems.
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