From the «use less water» department:
Feed: SoylentNews
Title: Ultrasound Reveals Trees’ Drought-survival Secrets
Author: janrinok
Date: Wed, 26 Apr 2023 09:53:00 -0400
Link:
https://soylentnews.org/article.pl?sid=23/04/25/1345232&from=rss
upstart[1] writes:
Scientists turned a forest into a lab to figure how some species cope with repeated dry spells[2]:
The tissues of living trees may hold the secrets of why some can recover after drought and others die. But those tissues are challenging to assess in mature forests. After all, 90-year-old trees can't travel to the lab to get an
imaging scan. So most studies of the impacts of drought on plants are done in the lab and on younger trees — or by gouging cores out of mature trees.
[...] In the Kranzberg Forest outside Munich, the team outfitted stands of mature spruce and beech trees with rugged, waterproof ultrasound sensors. Some of the stands had been covered by roofs to block the summer rain, creating artificial drought conditions.
Five years of monitoring revealed that beeches (Fagus sylvatica) are more drought-resilient than spruces[3] (Picea abies), the team reported in the December Plant Biology. Delving into the underlying mechanisms explained this difference.
Drought-stressed trees produced more ultrasound signals than trees exposed to summer rains. Those faint acoustic waves were bouncing off air bubbles called embolisms deep within the trees' vasculature. Surface tension keeps water moving[4] through a tree's thousands of tiny vessels — evaporation from pores in leaves drives water up the trunk (SN: 9/6/22). But if there's insufficient water in the soil, this upward pull can generate embolisms that clog vessels. In the experiments, spruces pinged much more than beeches, suggesting they had far more embolisms.
That's despite the fact that beeches appear to be less conservative with their water management, at least above ground. Trees can prevent embolisms by
closing the pores on their leaves, but there's a trade-off. Doing so cuts off the supply of the carbon dioxide that drives photosynthesis, which makes the carbohydrates and sugars that trees need to live and grow. In dry conditions, trees face an impossible choice "between starving and dying of thirst," Beikircher says.
Read more of this story[5] at SoylentNews.
Links:
[1]:
https://soylentnews.org/~upstart/ (link)
[2]:
https://www.sciencenews.org/article/ultrasound-trees-drought-survival-secrets (link)
[3]:
https://onlinelibrary.wiley.com/doi/10.1111/plb.13444 (link)
[4]:
https://www.sciencenews.org/article/plant-sap-water-power-energy-world (link)
[5]:
https://soylentnews.org/article.pl?sid=23/04/25/1345232&from=rss (link)
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