Conifer communication is altered by air pollution

Conifers are dominant tree species in boreal forests that are susceptible to bark beetle attacks. When under attack, the trees release volatile organic compounds to warn neighboring seedlings. These are the findings from a new study out of the University of Eastern Finland.

When plants are damaged, they release odorous chemicals into the atmosphere as a way to communicate. This defense mechanism had not been identified in conifer trees. 

“We decided to look at whether conifers undergo a similar response and were amazed at the results,” said study co-author Hao Yu.

The experts found that when Scots pine seedlings are damaged by bark-feeding weevils, they release volatile chemicals into the atmosphere. Undamaged plants exposed to these chemicals also start to release volatiles and prepare themselves to emit more once they are under attack. 

“This observation is novel and has broad implications for further research investigating the mechanisms of how plants obtain information from their neighbors,” said Professor James Blande.

After the warning, receiver plants altered resin duct traits, and were subject to reduced amounts of damage by pine weevils. The researchers also discovered that receiver plants had increased their net photosynthesis rate.

The team investigated the responses of receiver plants under elevated ozone conditions to represent more polluted regions. They found that the responses were significantly altered, but the final defense outcome was not affected.

“The different responses of receiver plants made us think that the communication process was eliminated, but receiver plants still had more resistance to weevils,” said Yu. 

The research sheds new light on conifer communication, and indicates that it can be substantially altered by air pollution.

The study is published in the Proceedings of the Royal Society B: Biological Sciences.

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By Katherine Bucko, Earth.com Staff Writer