ARBOREAL COMMUNISM ? N O T
(c) 1997 Ian Williams Goddard
SCIENCE NEWS [1] recently reported a study
purported to have found an example in nature
of organisms practicing the communist ethic
"from each according to ability, to each
according to need." This alleged communist
conspiracy includes the Paper birch [2],
the Douglas fir [3], and several fungi [4].
SN proclaims that this study "challenges
the current ecosystem models, which assume
that plants constantly compete with one
another for resources." That extrapolation
is, however, not supported by the evidence.
WHAT THE STUDY SHOWS
The study found that carbon dioxide (CO2)
in the form of sugar is distributed from
the roots of trees in the sun with the most
CO2 to the roots of trees in the shade with
the least CO2. This egalitarian transfer is
performed by a network of subterranean fungi.
The result is a more equitable distribution
of CO2 than would otherwise exist in the
arboreal community. As SN states:
The [research] team showed that
some trees give their neighbors
carbon that they have captured
from the atmosphere. An under-
ground network of fungi collabo-
rates in transporting the goods.
... The network envelops the
roots of both types of trees.
The scientists discovered that
shade [ or need ] enhances a
tree's ability to receive [CO2].
Irrespective of this fungi-facilitated sub-
sidy, the trees have a symbiotic relation
(mutualistic symbioses) with the fungi in
which the trees give the fungi CO2 in ex-
change for nitrogen (N) and phosphorus (P),
which the fungi liberate from the soil.[5]
It is after this tree-fungus exchange that
the fungi will then transfer some of their
earned CO2 to trees in need of CO2.
This process of redistribution subsidizes
CO2-starved trees that are shaded under the
canopy of larger trees that take up all the
direct sun. The researchers found, however,
that as a rule, birch trees tend to experi-
ence a net loss while firs enjoy a profit.
WHO SUBSIDIZES WHO?
With the SN report entitled "Communism In
Trees Goes Underground," the presentation
of the study by SN promotes confusion by
suggesting that this egalitarian distribu-
tion can be attributed to the trees them-
selves, when in fact it can only be attrib-
uted to actions of the "middle men fungi."
Statements like these cause this confusion:
Although plants don't plot to
overthrow capitalist regimes,
their actions demonstrate a
clear communist bent. ...
... trees give their neighbors
carbon... Birches subsidized firs...
Let's think for a moment: if you gave the
baker $5 for bread and then the baker gave
$2 to the poor, it would be erroneous to
say that you subsidized the poor. Yet that's
just what SN is saying by suggesting that
because Tree 1 (T1) gave fungus (F) CO2 in
exchange for N and P, and then F gave Tree
2 (T2) some of that CO2, therefore T1 has
subsidized T2 -- a false conclusion.
exchange subsidy
| |
(TREE 1) <---> (FUNGUS) ---> (TREE 2)
T1 gave x to F in exchange for y, therefore
T1 subsidized neither F nor T2. F, not T1,
subsidizes T2. Because T1 does not subsidize
T2, the extrapolation presented by SN that
this study "challenges the current ecosystem
models, which assume that plants constantly
compete with one another for resources" is
simply NOT supported by the evidence.
(It should be noted that while fungi are
members of the kingdom Fungi, which is a
division of the kingdom Plantae, fungi are
not plants; so to claim that the plants
in the study subsidize each other is false.
Mutualistic symbioses -- not an example of
the communist ethic -- between plants and
fungi is already well-established. [5])
The fact is that the evidence presented in
the study indicates only self-interest on
the part of all the organisms in the study.
NAKED SELF-INTEREST RULES
The only possible instance of a subsidy
and thus of "communism" to be found in the
study is the "gift" of CO2 by the fungi to
trees in need of CO2. In this way it could
be said that the fungi act like Robin Hood
-- taking from the rich to give to the poor.
But what's in it for the fungi?
The answer seems obvious to me: I suspect
that the fungi feed weaker trees that grow
in the shade beneath larger sun-drenched
trees because this subsidy ensures that
trees will shade the ground more constantly
than they would without the subsidy, thereby
maintaining the dark, damp, and cool condi-
tions that the fungi need to survive.
If, due to lack of CO2, smaller trees did
not exist under the dark canopy of large
trees, then when those large trees died --
particularly if many died suddenly -- the
ground would be exposed to more sunlight
than if a new crop of smaller replacement
trees were always waiting under the canopy
to quickly fill the vacated space. Maintain-
ing such an "assembly line" of trees en-
sures the constant shade the fungi need.
Maintaining a constant rotation of trees also
ensures a continuous supply of falling dead
trees, which the fungi consume. Which is what
one of the researchers suggested, hypothesiz-
ing that by feeding the weak, the fungus may
be "planning for its next meal." [1]
Through exchange with Tree 1 (T1), Fungus (F)
subsidizes Tree 2 (T2). When T1 dies, T2 is
ready to take the place of T1. F then subsid-
izes T3 via exchange with T2 in preparation
for the death of T2, and so forth... sustain-
ing a continuous life-support system for F:
(TREE 1) <---> (FUNGUS) ----> (TREE 2)
(T1 dies) ----> (FUNGUS) <---> (TREE 2)
(TREE 3) <---- (FUNGUS) <---> (TREE 2)
(TREE 3) <---> (FUNGUS) <---- (T2 dies)
(TREE 3) <---> (FUNGUS) ----> (TREE 4). . .
(The fungi may feed firs more than birches
because firs provide not only more darkness,
but, being evergreens, provide it more con-
stantly. The fungi might support a species,
such as the birch, that provides less of
what it needs simply because if the fungi
supported only one species of tree and a
disease wiped out all of that tree, the
fungi would have no trees and no shade.)
It stands to reason, based upon the evidence,
that the system of egalitarian CO2 distribu-
tion maintained by the fungi exists only to
sustain a continuos life-support system for
the fungi. There is no reason to believe
that the fungus or any organism in the study
acts out of selfless "communist" altruism.
IN CONCLUSION
Rather than fulfilling the romantic role
of a Robin Hood, the evidence suggests that
the fungi act like a farmer who maintains
an egalitarian distribution of resources
to his crops, such that if one field grows
more slowly, he gives it more water and
fertilizer from the common supply than he
gives to crops growing more quickly. In
this most likely scenario, the "gift" that
the fungi give to the weaker trees is no-
thing but an act of naked self-interest,
not altruism, on the part of the fungi.
While the fungi do take from the rich and
give to the poor -- most likely out of self-
interest -- the study uncovers no evidence
of selfless subsidy, no evidence of altruism,
and therefore no evidence of arboreal com-
munism. Furthermore, the SN extrapolation
that the study "challenges the current eco-
system models, which assume that plants
constantly compete with one another for
resources," is not supported by the evi-
dence in the study. Apart from my disagree-
ment with the SN extrapolations, I still
think SN is an excellent publication.
_________________________________________
[1] SCIENCE NEWS: Communism In Trees Goes
Underground. E. Strauss. Vol. 152, 8/9/97.
http://www.sciencenews.org/sn_arc97/8_9_97/fob2.htm
The study, which doesn't make the extrapo-
lation that SN makes, was published in:
NATURE: Net Transfer of Carbon Between
Ectomycorrhizal Tree Species In The Field.
S. W. Simard, Vol. 388, August 7, 1997.
http://www.nature.com/
[2] Paper birch (Betula papyrifera)
http://www.streetside.com/plants/floridata/ref/b/betula_p.htm
http://www.mpelectric.com/treebook/fact18.html
[3] Douglas Fir (Pseudotsuga menziesii)
http://www.cof.orst.edu/cof/teach/for241/con/dfgen.html
http://www.isc.tamu.edu/FLORA/imaxxpin.htm
[4] About the fungi varieties in the study,
the study states that "Seven ectomycorrhizal
morphotypes were common between B. papyrifera
and P. menziesii, covering over 90% of their
root tips..." NATURE (8/7/97) page 580.
[5] Plant<->fungi mutualistic symbioses
is known as mycorrhizae. For more info:
http://users.caribnet.net/~lec/types.html
The type of mycorrhizae occurring in the
study is Vesicular-arbuscular mycorrhizae:
http://users.caribnet.net/~lec/vaminfo.html
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