To Gauge Impact of Nitrogen Pollution, Sri Lanka Project Looks to Lichens

When a study published in January flagged the risks to Himalayan forests from excessive atmospheric nitrogen pollution, it relied on an often-overlooked member of the ecosystem to assess the level of the threat: lichens.

A composite organism of algae and fungi, lichens, like plants, need nitrogen in order to thrive. But too much of it — either in the air, in the form of ammonia, or when it settles on soil and vegetation, in a process known as deposition — can be damaging.

And that was the message these bioindicators were sending back, with headline findings that up to 85% of Himalayan forests are impacted by critical levels of ammonia, and up to 98% by total nitrogen deposition.

Now, some of the researchers behind that study are digging deeper into the findings, focusing again on lichens, which cover an estimated 8% of Earth’s land area, but this time narrowing down on an experimental plot in central Sri Lanka.

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