John Faithfull 🌍πŸ‡ͺπŸ‡ΊπŸ΄σ §σ ’σ ³σ £σ ΄σ ΏπŸ§‘βœŠπŸ»βœŠπŸΏ
Interesting to see 115 years of lichen growth: the same outcrop of metamorphic rock in Mull from a photo published in 1910, and from last year. Given that deglaciation was ca. sixteen-and-a-half thousand years ago, the early C20th outcrop was still remarkably free of lichen. Over the last century lichen growth seems to have become turbocharged. Changed climate? #Lichen #Lichenodon #LichenSubscribe #Mull #Geology
Nov 6, 2023 at 3:25pmWeb
Show threadSulfide_SleuthNov 6, 2023
@FaithfullJohn
I think you'll find if you read the methods section of that paper that the oucrop was scrubbed with bleach prior to that picture being taken.
Was standard practice in the UK into the 60-70s, and in North America until the late 90s (although I hear rumors of oldtimers in Canada still doing this before bigger field trips).
My guess is that the licen growth is more like 50-60 years. Possibly more recent if it was a field trip stop for any undergrad program.....
Show threadBashStKidNov 6, 2023
@PhilGopon @FaithfullJohn That's interesting, thank you.
I guess you could also date it by too late for bleach, but too early for 1" core drills all over the outcrop ...
Show threadJohn Faithfull 🌍πŸ‡ͺπŸ‡ΊπŸ΄σ §σ ’σ ³σ £σ ΄σ ΏπŸ§‘βœŠπŸ»βœŠπŸΏNov 6, 2023
@PhilGopon I did wonder about that - I've sometimes thought of doing it myself! But I don't think it's likely in remote areas of Mull before 1910. Might try to find out more about this though - any knowledge of bgs photographers doing this back in the day @scotfot ?
Show threadBob McIntoshNov 7, 2023
@FaithfullJohn @PhilGopon No, I've not heard about this sort of pre-photography treatment - The majority of early Survey photos seem to be views, close outcrop photos are in a minority. Outcrop photos increased in later years - especially with colour photography - no metrics on this, just an impression!
Show threadJohn Faithfull 🌍πŸ‡ͺπŸ‡ΊπŸ΄σ §σ ’σ ³σ £σ ΄σ ΏπŸ§‘βœŠπŸ»βœŠπŸΏNov 8, 2023
@scotfot @PhilGopon Yes -that's my impression too: I've never seen mention of bleach being taken as fieldwork kit in any old field notes / archives at the Hunterian. Which is not to say that it's not a good idea 😈
Show threadCatherine Rowan JonesNov 6, 2023
@FaithfullJohn
Changed climate (warmer, wetter) is likely a factor, I think, augmented by aerial nitrogen perhaps.
IIRC David Elias considers this in his book "Shaping the Wild: Wisdom from a Welsh Hill Farm".
Additionally I found this article online:
https://pubmed.ncbi.nlm.nih.gov/33935994/
Do Aerial Nitrogen Depositions Affect Fungal and Bacterial Communities of Oak Leaves? - PubMed

The amount of nitrogen (N) deposition onto forests has globally increased and is expected to double by 2050, mostly because of fertilizer production and fossil fuel burning. Several studies have already investigated the effects of N depositions in forest soils, highlighting negative consequences on …

PubMed
Show threadPeter L BowdenNov 7, 2023
@FaithfullJohn I think I read somewhere that lichen thrives in less polluted air. So it might be an indication of the improvement in air quality over recent yearsπŸ€”
I like lichen on trees, not on the Lewisian😞
Show threadJohn Faithfull 🌍πŸ‡ͺπŸ‡ΊπŸ΄σ §σ ’σ ³σ £σ ΄σ ΏπŸ§‘βœŠπŸ»βœŠπŸΏNov 7, 2023
@PeterLBowden1 Yes - I wondered about that too. But on the far west coast air is pretty clean, and probably always has been. The smell of peat and coal smoke used to be a thing near houses sometimes, but this outcrop is over 200m away from one remote house, so pollution seems unlikely? I need to collect more auld rock pix, with dates, and see how consistent this lichen story is in different places... πŸ€“πŸ€”