Regent Street in London (Photo from https://www.bbc.co.uk/news/business-37522674)

Dear Readers, before we get on to the main subject of my piece today, I wanted to say a few words about the violence  being wreaked across the country by far-right thugs. If you belong to one of the groups that this hatred has been aimed at, please know that the vast majority of people are appalled at the racism and Islamophobia being expressed and are horrified by the wanton destruction that is happening in local communities, some of it aimed at the most vulnerable people in our society. These thugs do not speak for me, nor i’m sure for the people who read this blog,  And if you are not in one of the groups that are being targeted, and have friends or neighbours who are, it’s worth reaching out to see how they’re doing, and to offer your support. I have a Muslim friend with two small children, who has lived here all her life, and is now afraid to go out. What a terrible state of affairs.

Like so many people, I’ve been appalled by events such as the destruction of the Citizen’s Advice Bureau office in Sunderland (for those who don’t know, these are often the only places offering free advice on debt, housing etc to the poorest people in a location) and the attack on the Spellow Lane library in Liverpool, with all  the shelving and books destroyed. I can’t find a Go Fund Me  for the Citizen’s Advice Office, but there is one for the library, so if you have a few quid lurking  down the back of the sofa, this wouldn’t be a bad place to put it.

Anyway, back  to the nature! I’ve written before about the problem with street lights being left on all night, and the way that affects the insect population, but a recent Chinese study has pointed out that something more subtle has been going on. Scientist Dr Shuang Zhang of the Chinese Academy of Sciences noticed that trees growing in urban  settings had far less insect damage than the same species in  rural settings. The study centred on two species – the Japanese Pagoda tree (a popular street tree in the UK) and green ash trees.

Japanese Pagoda tree (Sophora japonica) Photo By Jean-Pol GRANDMONT – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=5618874

Green Ash (Fraxinus pennsylvanica) Photo By Jerzy Opioła – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1796487

The Japanese Pagoda tree in particular has soft, juicy leaves that are normally eaten by a whole variety of insects, but in the areas of highest illumination  they were practically untouched. The scientists visited 30  sampling sites, and looked at the size, toughness and chemical composition of over 5500 leaves.

The hypothesis had been that the increased hours of light would enable the plants to photosynthesize for longer, which could give one of two results – larger leaves, or leaves that were better defended. The study showed clearly that the second hypothesis fitted what was happening – the leaves that were exposed to the most light for the longest time were thicker and had much higher levels of tannins, which are used as a chemical defence against insects. Some of the most brightly-lit trees had not been nibbled by insects at all.

Although these trees might look nicer than those that have been munched upon, Dr Shuang Zhang points out that the caterpillars that eat the leaves are part of a food web that includes the birds and other insects that eat them, and the birds of prey that eat the birds, to mention just a few links.

it’s a bit of a conundrum – it’s important to keep cities safe for those who use them, but surely there’s a way to devise lighting that doesn’t have such a bad effect on animals? Or maybe we could turn at least some of them off at night? And if we have lights in our gardens, can we turn them off when we’re going inside? I shall be interested to see what further research reveals about light pollution and its effects on the natural world.