[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) 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?
I suggest you post this question to the Bryonet listserve. Contact
jmglime at mtu.edu
Dorothy J. Allard, Ph.D.
Analytical Resources, L.L.C.
1331 Waterville Mountain Road
Bakersfield, VT 05441
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
301 N. King St.
Shepherdstown, WV 25443 U.S.A.
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
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
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>
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>
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)
-find some actual insects feeding
-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
-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.
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)
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
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
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.
Div of Entomology, CSIRO,
GPO Box 1700,
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
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" <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,
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.
Contact information: http://delta-intkey.com/contact/dallwitz.htm
DELTA home page: http://delta-intkey.com
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
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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