[Taxacom] moss circle replies

Charles R Parker chuck_parker at usgs.gov
Fri Mar 23 10:03:01 CDT 2007

Thanks to everyone who has responded so far.  Below I have copied the 
responses received thus far. 

To summarize, basically nobody knows what's happening, but John Landolt 
and Mike Dallwitz both referred us to papers in which similar patterns are 
explained by a fungal infection.  Both of these examples occur in the 
Arctic.  So, a fungal infection clearly fits the pattern, but this 
apparently is the first record of this type of thing happening outside the 
Arctic region.  Now we need to confirm that this is the case here.

As far as snail or other invertebrate grazing, there is no slime or frass 
associated with these, but that is not conclusive by itself.  So grazing 
remains a possibility.

Freezing and thawing were suggested for the Arctic moss rings, but that 
hypothesis was rejected for several reasons by Wilson (J. Ecology 1951). 
DK Singh also has not seen anything like it in the Himalayas, where it 
does get cold.  Besides, these examples are from low elevations (<1000 m) 
in the park, and we have had very mild winters the past several years, 
with little snow or ice to speak of.

Finally, all of the logs are lying on the ground.  They are not standing 

I'll let you know if we are able to confirm the fungal infection 

Charles R. Parker, PhD
Research Aquatic Biologist
USGS Biological Resources Discipline
1314 Cherokee Orchard Road
Gatlinburg, TN 37738-3627

Chuck_Parker at usgs.gov
(865) 436-1704
(865) 430-4753 [fax]

Recently, circles were discovered in moss living on barkless pine logs in
an area of the Great Smoky Mountains National Park in Tennessee.  A good
number of logs having moss had the circles.  Examples can be viewed at

Most of the suggestions we have come up with for the origin of these
features are as fanciful as those advanced to explain crop circles
(miniature aliens, drunken snails, etc.).  Anyone have any knowledge of
these and of what causes them?


Hi Chuck,
I suggest you post this question to the Bryonet listserve. Contact 
jmglime at mtu.edu
(Janice Glime)
Dorothy J.  Allard, Ph.D.
Analytical Resources, L.L.C.
1331 Waterville Mountain  Road
Bakersfield, VT 05441

fax 802/827-3617
cell  802/279-4249


This is probably way off the mark, but I did run across the following 
paper that describes a fungus disease in arctic/antarctic mosses that 
produces circular and "concentric circles" of moribund moss in moss mats.


How are things going otherwise in the Park these days?

Good luck with the moss circle puzzle.  I'd be interested in it's final 



John C. Landolt
Department of Biology
Shepherd University
301 N. King St.
Shepherdstown, WV 25443 U.S.A.
Ph: 304-876-5357
jlandolt at shepherd.edu

Looks like grazing to me. Perhaps by snails or slugs? Are there
remnants of slime trails with the tracks?

John D. Oswald
Associate Professor
Department of Entomology
Texas A&M University
College Station, TX  77843-2475

E-mail: j-oswald at tamu.edu
Phone: (979) 862-3507
More at: http://insects.tamu.edu/people/faculty/oswaldj.cfm

Dear Chuck,

The look to me to be made by a gastropod (snail or slug) of some
sort.  One often will see similar patterns in algae on rocks and
aquarium glass from aquatic snails.


David Remsen <dremsen at mbl.edu>

Hi Chuck,
I am guessing, but will suggest insect.  I do not see enough
slime trail for it to be a mollusc.

"Robin Leech" <releech at telusplanet.net>

Hi Chuck, 

I looked at you moss circles from an e-mail Re: Robin Leech. 

If it was an insect I would expect to see: 
-maybe different sized channels based on the larvae/insect growing (only 
if it occurred over an extended period) 
-some excreta 
-find some actual insects feeding 

I wonder: 
-are all the "circles" the same size - width 
-what time of year they occur 
-any observations on insects in the area 
-the shape, is circular in some but linear in others, or is it 
predominately circular 
-location on the logs, are they perimeter re; access or are they high/low 

I guess I'd try to rule out a few things like rabbits (low and perimeter), 
flying animals (?), tall animals (?) etc. 

Jim Broatch
Insect Pest Management Specialist
Postal Bag 600, 4705-49 Street
Stettler, Alberta. T0C 2L0
Ag-Info Centre: Toll Free in Alberta 1-866-882-7677
or 310-FARM (3276)
Cell (403)877-4687
e-mail to: jim.broatch at gov.ab.ca

"We are continuously faced with a series of great opportunities, 
brilliantly disguised as insoluble problems." -John A. Gardner

Just as a curiosity, there is a lichen that looks similar to the crop 
circles in the moss:
see great photos at 

Parmelia centrifuga
When I took botany in Sweden, it was nicknamed "Russian Empire" since it 
expanded outwards and died from the inside, but the real Swedish name is 
"Winter Lichen".

Lena Struwe
Rutgers University

Lena Struwe <struwe at AESOP.Rutgers.edu> 

Some fungi are renowned for forming "fairy circles", etc., of fruiting 
bodies.  Could there be an analogy here.

Don Colless,
Div of Entomology, CSIRO,
GPO Box 1700,
Canberra. 2601.
Email: don.colless at csiro.au
Tuz li munz est miens envirun 

I did not look at the moss circles, but many vascular plants form
circles as they grow out from the center. I have always taken it that
individual plants do not survive for long and that the ground that they
grew in is left less rich in the nutrients the young plants need as the
area outside. No, I have not tested any part of this.

"Mary Barkworth" <Mary at biology.usu.edu>


After looking at the moss photos again I recant my suggestion that it 
was caused by snails.   After looking at the high resolution photos I 
am less convinced because much of the moss is left behind whereas I 
would have thought a grazing gastropod would remove more material.

Meredith Lane, a botanical colleague thinks it is a fungus causing 
the pattern.

A real mystery.

David Remsen <dremsen at mbl.edu> 

    Well, I don't know the answer, but I will add another possibility. 
Given that these were found in late winter, could this pattern be the 
of slowly receding patches of ice (or snow)?  Each ring of moss could form 

at one favorable time of day along the wet edges of the sheet of ice.  At 
night the thin edges of ice would just evaporate leaving a ring of drier 
wood surface.  The next day another wet ring forms (along the receding 
that would be suitable for the moss.

    Of course, the drier "rings" would eventually get wet and the moss 
fill in those gaps, but in the meantime you could have a tree-ring pattern 

of alternating moss and drier wood.  I would think this would be more 
if the ice patch was in the shade and not in direct sunlight, but this is 
all just an educated guess.
             Ken Kinman

"Ken Kinman" <kinman at hotmail.com>

fungi attack ?

(expanding fungi myceliums can make enlarging circles...)

just a guess


pierre deleporte <pierre.deleporte at univ-rennes1.fr> 

Heh!  Posts from people who didn't look at the photos! Fantastic!

Just to clarify (I looked at the hi-res photo) - these look somewhat 
like typical grazing traces of a small invertebrate (like a mollusc or 
caterpillar), except that the moss is seemingly partly still there but 
turned brown (no chlorophyll).

Does that help anyone?

Geoff (knows nothing about moss or moss eaters)

   Geoff Read <g.read at niwa.co.nz>

     I don't much about moss-eaters either, but I am still not convinced 
something munched through healthy moss to produced these fairly concentric 

dead "rings".  Any brown moss in these rings could just as well be moss 
plants that tried to grow but just didn't have enough moisture.

      In my "receding ice patch hypothesis", the ice above these dead 
simply freeze-dried during the cold nights and mornings.  Perhaps during 
warm afternoons when the temperature rose above freezing, enough liquid 
water would melt around the edge of the receding ice that moss could get a 

start in that thin zone ("ring"), and once established could hold onto 
enough moisture to keep from freeze-drying.  Any moss trying to get 
established in the dead zones would be freeze-dried to death and turn 
during the night.

      If these were grazing trails, are they really typical?  Aren't they 
typically more random and even looping around and sometimes crossing back 
over themselves?  Especially looking at the left photo (#5) which is oddly 

symmetrical and oval.  I propose that the top central part of that oval is 

where the last of the ice patch (then rather thin) finally melted when 
temperatures were high enough to prevent nighttime freeze-drying of the 
spot.  The moss therefore covered that part of the oval rather quickly 
only after the photo was taken did the dead zones in rest of the oval area 

get wet enough to allow moss to grow without drying out).  Anyway, lack of 

moisture (due to freeze-drying) just seems a more parsimonious explanation 

to me than munching invertebrates (especially in late winter).

"Ken Kinman" <kinman at hotmail.com> 

Dear Dr Charles R. Parker,

Its really strange. I have never observed such pattern during my over 32 
years of experience in the Indian Himalayan region. What's the species, 
any way?


D.K. Singh

Dr D.K. Singh
Botanical Survey of India
CGO Complex, 3rd MSO Building
Salt Lake Sector I
Kolkata - 700 064 (INDIA)
Ph. : +91 33 23214050
E-mail: singh_drdk at rediffmail.com 

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 
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. 
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 
brown regions were narrower? They may provide better clues.



> Aren't [grazing trails] typically more random and even looping
> around and sometimes crossing back over themselves?

Not always - see Scribbly Gum Moth at

Notice that the larva turns around and comes back parallel to its earlier
track. The track never crosses itself.

For an explanation of moss rings, and diagrams of different patterns, see
J.W. Wilson, 1951. Observations on Concentric 'Fairy Rings' in Arctic Moss
Mat. J. Ecology 39, 407-416.

Mike Dallwitz
Contact information: http://delta-intkey.com/contact/dallwitz.htm
DELTA home page: http://delta-intkey.com

Hello Chuck,

I took a look at two photos posted, moss rings #5 & 7.  To me they 
appear to be the result of herbivory, some invertebrate.  I can't tell 
from the image, but could the "moss" be liverwort, perhaps a 
Cephalozia or Nowellia?  Well I went back an found the larger file and 
yes, you have liverwort but the leaves look rounded, perhaps 
Jamesoniella or Odontoschisma.  Plant material is not taken down to 
xylem.  I'm not sure if the dead bryophyte is the same liverwort (or 
liverworts) or a dead moss underneath.  Another wild idea would be the 
excretions of a millipede, millipedes sometimes amass, perhaps they 
had a circle gathering?

I will gladly examine the material more closely if you send any to 
me.  I like puzzles and have looked at quite a few specimens of 
regional bryophytes with a hobby interest in invertebrates.


Paul G. Davison, Ph.D.
UNA Box 5232
Department of Biology
University of North Alabama
Florence, AL  35632

Phone (256) 765-4434
Fax (256) 765-4430

We are probably going to find out that the perp used a small electric 
razor to
shave the paths.

As a follow-up to the Mike Dallwitz references to moss circles, see:


I had previously sent this to Chuck Parker as a "way out"
possibility, but perhaps not so much.  Are there any other
correlations between the Smokies and arctic biology?

John C. Landolt

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