Artificial light at night counts as a nuisance for insects, and it falls on the trees as well. The researchers collected thousands of leaves from trees growing in pairs: one beside a streetlight and one in a darker spot. What was the difference?
Tougher leaves and fewer bites. Across almost 5,500 leaves and both species, the higher the light at night, the lower the share of leaves that had been eaten. One species showed greater and the other a change in its defensive compounds, which is mechanical defense in one and chemical in the other. Intact leaves may look healthy, and they pass less energy to the insects and the birds that eat them.
Intact leaves look like a sign of health, and under they mark something else.
The researchers ran , collecting almost five and a half thousand leaves from trees growing two by two: one beside a streetlight and one in a darker spot. Pairing like that cancels soil, climate and air pollution.
In both species, the higher the light at night, the lower the share of leaves that had been eaten. One species showed greater leaf toughness and the other a change in the concentration of its defensive compounds, which is to say mechanical defense in one and chemical in the other.
The result is not good news. runs through the bite: a leaf that goes uneaten does not feed the insects, or the birds that depend on them. So a streetlight changes not only the night sky but the urban food chain. This is observational work in one city and two tree species, and the insect population was not measured directly.
wat. Almost 5,500 leaves from Beijing showed that strong night lighting goes together with tougher leaves and fewer insect bites.
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A streetlight changes not only the night sky but the relationship between tree, insect and bird inside an urban food chain.
How do we know?
A paired field survey examined 180 trees of two species at 30 urban sites, measuring light, toughness, nutrients and the share of leaves eaten.
What is still unknown
This is observational work in one city and two tree species. The association is consistent and does not show that light alone caused every change, and the insect population was not measured directly.
Learn something?
Where to next
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