Artificial lighting and climate change: CNR investigates their combined effects on trees
Does climate change affect the life cycle of plants, and how? And does artificial lighting affect their vegetative season?
A study conducted by the Institute of Biometeorology of the National Research Council (CNR-IBIMET), published in the journal Urban Forestry & Urban Greening, helps to answer these questions.
The research started from the fact, observed a few years ago, that plane trees near street lights in Florence maintained green leaves in late winter.
“In 2015, green branches were observed on trees near street lights until February, during a particularly mild autumn-winter period”, explained Luciano Massetti from CNR-IBIMET. “In the following two years, of the more than 200 trees lining three avenues in the city centre and suburbs, the percentage of trees with green leaves under luminaires was significantly higher until the end of December, in some trees until the end of January, whereas plane trees less exposed to light were completely bare of leaves. In many cases, the lamp posts are completely surrounded by the foliage of the trees”.
These results indicate that the vegetative season of trees can be affected by artificial lighting. “To survive the reduction of daylight hours and the lower temperatures in winter, deciduous trees go into the so-called vegetative season that ends in spring. Our study seems to suggest the combined effects, increasingly frequent and intense, of artificial lighting and progressive increase in winter temperatures caused by climate change”, concluded Massetti.
The study was presented at the international symposium on the promotion of the night sky on Capraia, organized by CNR-IBIMET in collaboration with University of Pisa, Attivarti.org and with the support of Regione Toscana and the international project Stars4all.