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Post by ayjay on Jan 17, 2017 22:20:02 GMT
I took my car in for a service, went for a wander while it was being done and noticed this. Lichen on a roadsign, it's only growing on the dark areas but also only directly adjacent to the white areas.  |
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Post by rowanberry on Jan 19, 2017 19:48:14 GMT
Now that is really strange! Why would it do that, I wonder?
I know that flies will sun themselves on white walls whenever it's cool, so could it be that the surface temperature was too warm on the white stripes and so the lichens preferred being close to it, but not exactly on it?
Or perhaps, (just had another thought) there was a tiny gap where the black and white meet, and they were able to colonise there from the metal that might have been rusting there?
I'm glad you post it, though- it is curious.
Edited to add.... Snowlynx has just come up with another theory... if those are decals rather than paint and are glued onto the surface, then maybe the lichens are attracted to any glue that oozed out along the joins?
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Post by ayjay on Jan 19, 2017 22:37:24 GMT
My theory is based more on heat and light, the black will be warmer, but adjacent to the reflective white provides the most light.
There's also moisture to consider, maybe the more shiny white surface will attract condensation/dew/or whatever more readily than the matt black surface and it's likely to run off the shiny white surface onto the black, so closest to the white provides more moisture.
It's all just a guess though.
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Post by Tringa on Jan 29, 2017 16:15:19 GMT
I missed this when you posted it Ayjay.
I don't know how the sign is made but I wondered if there are joins between the black and white areas and if so, perhaps water collects in the joins and this assists the growth of the lichen.
Dave
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