Last summer I ruminated about whether urban plants are able to “sleep” in the presence of street lamps. (It sure is difficult for those of us humans with a light shining right into our window!) My mind came back to this question as I was taking a few more pictures of plants at night. Above, truckers take their night’s rest next to the trees in the parking lot of a Lowe’s below the Smith Street subway station in Brooklyn.
Continuing my query from last summer, I Googled “urban plants streetlamps.” This time around, I got a little more information.
First in my search results was a page about a conference in 2002 on “Ecological Consequences of Artificial Night Lighting.” In the list of lecture abstracts, the first, on plant photoreceptors, came to the following inconclusive conclusion:
“There is virtually no rigorous research on the influence of urban lighting on plants. There are anecdotal reports of leaves of deciduous trees failing to senesce in proximity to streetlights because they perceive a long day instead of a short one, but little else. While it is highly likely that urban light does affect plant development, research is badly needed to assess what the effects might be.”
Presumably more research has been made since then. Upon visiting the homepage of www.urbanwildlands.org, one of the groups that hosted the conference, I saw plenty of up-to-date news and saw that a book came out in 2005 with the same title as the conference. But it seems that there’s a lot more research out there on how street lights affect urban wildlife rather than plants.
The second result in my Google search was perhaps more definitive. It linked to the Wikipedia page on “Street light” (which has nice street lamp photography, by the way!). If you scroll down to the part on light pollution, it talks about plants in a single, authoritative sentence (no footnote or anything!):
“The light pollution also disrupts the natural growing cycle of plants.”
urban plant research 
Hello Sara!
This is a fascinating and somewhat sad topic. I remember once reading about a British supermarkt chain who were proud of the fact that the street lamps on there open air parking lots faced downwards rather than up to the sky. Apparently this is “better” for wildlife. I am not so sure.
Man knows no limits, it is too unfortunate, too often.
Many regards!
Jo
These pictures are beautiful! I love to look at plants in glowing windows at night time. Maybe we can do night photography together during our residency at Open Source.