[Taxacom] liverwort circles

[Ken Kinman]

     I would tend to agree with Dave that grazing is an unlikely cause.   
And also that fungal causes are unlikely, although that hypothesis sure 
beats grazing in my opinion.

      I do not believe that the mild winter would negate my "receding ice 
hypothesis".  It could be as simple as cold meltwater dripping onto the logs 
from branches above, which then refroze (then followed by the process of the 
ice receding over a period of days or even weeks).  Even in this scenario, I 
suppose fungal infection could be a secondary factor (but does it 
necessarily have to be the primary factor?).

     I haven't yet gotten access to Wilson, 1951, to see the reasons why he 
rejected a freeze-thaw scenario, but a paper referencing his paper states 
that the infected moss he studied was dead.  The present situation involving 
*living* bryophytes might be quite different.  I would also add that I'm not 
sure whether the bryophyte involved is a moss or a liverwort would make much 
of a difference (although any additional information could be helpful).

    Mere presence of fungi would not convince me that infection was the 
primary cause of these rings.  I'd need an explanation that is more 
convincing than the "receding ice hypothesis", and I haven't seen anything 
like that so far.  A little more context would be very helpful, especially 
whether there were branches or other vegetation above these logs which could 
have dripped water onto them to form ice patches.
   ---Not ready to concede,
           Ken Kinman    :-)
**********************************
>From: "Dave Jefferies" <d.w.jefferies at shu.ac.uk>
>Reply-To: d.w.jefferies at shu.ac.uk
>To: <taxacom at mailman.nhm.ku.edu>
>Subject: Re: [Taxacom] moss circles
>Date: Fri, 23 Mar 2007 11:18:04 -0000
>
>The patterns are intriguing.
>
>I think that mollusc grazing, or any grazing on the surface, is unlikely -
>no 'turning circles' for a grazer to move from one track to the next.
>
>Fungal causes are unlikely, I would expect something more like a fairy 
>ring.
>Of course the lichen comparison does challenge this. (And see below)
>
>Is there an underlying pattern in the bark or wood? This would give
>variations in the substrate that may be reflected in the moss growth. Fungi
>could then be associated if they had grown out from gaps in the bark, as
>could sub-surface grazing by insects sheltering under the bark.
>
>Were there examples of completely brown rings or where the gaps between the
>brown regions were narrower? They may provide better clues.
>
>Dave
>

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