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Flora ofNorth America
Narth
af Mexica
Edited by
FLORA
OF NORTH
AMERICA
EDITORIAL
COMMITTEE
VOLUME 27
Bryophyta,
part
1
--------
...
NEW YORK
OXFORD
•
OXFORD
UNIVERSITY
PRESS
•
2007
Economic and Ethnic Uses of Bryophytes
Janice
M.
Glime
Several attempts have been made to persuade
geo\ogists to use bryophytes for mineral prospecting.
R. R. Brooks (1972) recommended bryophytes as guides
to mineralization, and D. C. Smith (1976) subsequently
found good correlation between metal distribution in
mo sses and that of stream sediments. Smith felt that
bryophytes could solve three difficulties that are often
associated with stream sediment sampling: shortage of
sediments, shortage of water for wet sieving, and shortage
of time for adequate sampling of areas with diffieult
access. By using bryophytes as mineral concentrators,
sampies from numerous small streams in an area could
be pooled to provide sufficient materia l for analysis.
Subsequently, H. T. Shack\ette (1984) suggested using
bryophytes for aquatic prospecting. With the exception
of copper mosses (K. G. Limpricht [1885-]1890-1903,
vol. 3), there is little evidence of there being good species
to serve as indicators for specific minerals. Copper mosses
growalmost exclusively in areas high in copper,
particu\arly in copper sulfate.
o.
Mśrtensson and
A. Berggren (1954) and H. Persson (1956) have reported
substrate copper values of 30-770 ppm for some of the
copper
Introduetion
A general lack of commercial value, small size, and
inconspicuous place in the ecosystem have made the
bryophytes appear to be of no use to most people.
However, Stone Age people living in what is now
Germany once collected the moss
Neckera crisp a
(G. Grosse-Brauckmann 1979). Other scattered bits of
evidence suggest a variety of uses by various cultures
around the world
(J.
M. Glime and D. Saxena 1991).
Now, contemporary plant scientists are eonsidering
bryophytes as sourees of genes for modifying erop plants
to wirhstand the physiologieal stresses of rhe modern
world. This is ironie sinee numerous seeondary eompounds
make bryophytes unpalatab\e to most diseriminating tastes,
and their nutritiona\ va\ue is questionable.
Eeologieal Uses
Indicator
Species
mo ss taxa,
such as
Mielichhoferia
elongata,
Both Iiverworts and mosses are often good indicators of
environmental conditions. In Finland, A. K. Cajander
(1926) used terrestrial bryophytes and other plants to
characterize forest
types,
Their value as indicator species
was soon supported by A. H. Brinkman (1929) and
P.W. Richards (1932). Yet, bryophytes have a somewhat
different
M.
mielichhoferi,
and
Scopelophila.
Although no bryophyte seems to be restricted to
substrates containing iron, photosynthesizing bryophytes
have the ability to change soluble reduced iron to its
insoluble oxidized form and make this molecu\e visible.
A. Taylor
(1919)
discovered
that
iron compounds
place in ecosystems
than their tracheophyte
penetrated
the tissues of
Brachythecium
rivulare
and
neighbors.
14
ECONOMIC
AND ETHNIC
USES
15
formed a hard tufa;
J.
M. Glime and R. E. Keen (1984)
found a simiłar response in
Fontinalis,
where iron oxide
completely enveloped the moss in a hard cover. M.
Shiikawa (1956, 1959, 1960, 1962) found that the
Å‚iverwort
jungermannia vulcanicola
and mosses
Sphagnum
and
Polytrichum
play active roles in deposition
of iron ore. Since Japan has few native sources of usabłe
iron, S. Ijiri and M. Minato (1965) suggested producing
limonite ore artificially by cultivation
assemblages. L. F. Klinger et al. (1990) have suggested
that in the Holocene, succession went from woodłand to
peatland, with peat serving as a wiek to draw up water
and raise the water level, causing woodland roots to
became water-Å‚ogged. In New England, N. G. Miller
(1993) used bryophytes to support conclusions that the
flora during 13,500 to 11,500 BP had been tundra-like
vegetation similar to that presently in the Arctic.
of bryophytes in
fields near iron-rich springs.
One of the means by which bryophytes sequester both
metaIs and nutrients is to bind them by cation exchange
to cell walls of leaves. In this process,
Sphagnum
places
hydrogen ions in the water in exchange for cations such
as calcium, magnesium, and sodium (R. S. Clymo 1963).
Hydrogen ions make the water more acidic, and most
peatland ecologists argue that this is the primary means
by which bogs and poor fens are made more acidic.
While
Sphagnum
is a reliable indicator of acid
conditions, K. Dierssen (1973) found that several other
bryophytes successfully indieate other soil conditions. For
example,
Ceratodon purpureus
suggests go od drainage
and high amounts of nitrogen, whereas
Aulacomnium
palustre,
Pleurozium schreberi, Pogonatum alpinum,
and
Pogonatum urnigerum
signal less nitrogen, at least in
Iceland.
Funaria bygrometrica, Leptobryurn pyriforme,
and
Pohlia cruda
show good base saturation, whereas
Psilopilum laevigatum
indicates poor base saturation and
poor physical soil condition.
T. Simon (1975) demonstrated that bryophytes could
be used as indicators of soil quality in steppe forests, but
rheir absorption primarily of rain and atmospheric water
makes few of thern useful as pH indieators. H. A. Crum
(1973) considered
Polytrichum
to be a good acid
indicator; its abiliry to live on acid soils may be faeiłitated
by vascular tissue (hydroids and leptoids) in its stem. The
rhizoids at its base probably enhance uptake of water
and nutrients from soil.
Leucobryum
likewise indicates
acid soil, usually combined with dry, infertile, deep humus
(T. A. Spies and B. V. Barnes 1985).
Recentły, bryophytes have been used as indicators of
past climate. Although peatlands and their preserved
flora and even their fauna have long revealed the past,
we can now use bryophyte assemblages to expose past
climatie and hydrologie regimes. Understanding how
levels of evaporation and precipitation determine
composition of
Sphagnum
communities permits us to use
subfossil
Sphagnum
and other moss assemblages to
identify past cłimates (E. A. Romanova 1965;
J.
A. Janssens 1988). In another example, presence of
such droughr-tolerant species as
Tortella f/avovirens
in
subfossils indicates past dry climatic conditions in some
areas of the Netherlands
Erosion Control
Although legumes with their nitrogen-fixing symbionts
are usually planted to secure areas devoid of topsoil,
H. S. Conard (1935) suggested that sowing spores and
vegetative fragments of bryophytes on bare areas could
help to prevent erosion. In his home state of lowa,
Conard found that
Barbula, Bryum,
and
Weissia
were
important pioneers on new roadbanks, helping to control
erosion there before larger plants became established. The
protonemata that develop from both fragments and
spores form mats that cover and bind exposed substrates
(W. H. Welch 1948). In Japan,
Atrichum, Pogonatum,
Pohlia, Trematodon. Blasia,
and
Nardia
play a role in
preventing erosion of banks (H. Ando 1957). Even areas
subject to trampIing, such as trails, may be protected from
erosion by trample-resistant bryophyte taxa, and by those
wit h high regenerative ability (S. M. Studlar 1980).
On the orher hand, when bryophytes such as
Sphagnum
reach water saturation, they can suddenly
release a great load of water at unexpeeted times. Because
of its tremendous water-holding capacity,
Sphagnum,
ałong wirh
Calliergon sarmentosum,
controls water
during spring runoff in the Arctic (W. C. Oechel and
B. Sveinbjornsson 1978). When
Sphagnum
is saturated
and the layer above the permafrost melts, mosses
suddenly permit a vast volume of water to escape all at
once, creating problems for road-building engineers.
Nitrogen Fixation
Nitrogen is often alimiting nutrient for plant growth,
especially in agriculture. Bryophyte crusts, endowed with
nitrogen-fixing Cyanobacteria, can contribute
considerabłe soil nitrogen, particularly to dry rangeland
soiłs. Some of these Cyanobacteria behave symbiotically
in
Anthoceros
(D. K. Saxena 1981), taking nitrogen from
the atmosphere and converting it to ammonia and amino
acids. The excess fixed nitrogen is rełeased to the
substrate where it can be used by other organisms.
K. T. Harper and J. R. Marble (1988) found that
bryophyte crusts not onły help protect soil from wind
and water erosion, and providehomes for nitrogen-fixing
organisms, but they facilitate absorption
(H. Nichols 1969; J. Wiegers
and B. Van Geel 1983).
Similarly, our understanding
of past vegetation
is
and retention
enhanced
by information
about
past
bryophyte
of water as well.
E
16
ECONOMIC
AND
ETHNIC
USES
6.
Po/ytrichum
juniperinum
FIGURE
is an ubiquitous,
tall moss that holds
soi! in place,
looks
like a small tree in a dish garden,
and is strong
enough
to make
brooms,
baskets,
and
door
mats.
Photo
by Janice
Glime.
(1978)
reported
U. Granhall
and
T. Lindberg
high
to various
levels of S02, he determined
that most species
(0.8-3.8
g rrr? y-l) in
Sphagnum
by
10-40
hours
at
0.8
ppm S02,
nitrogen
fixation
rates
are injured
of exposure
or at
0.4
ppm after
20-80
hours.
communities
in a mixed pine and spruce
forest in central
Since that time, use of
Sweden; thus bryophytes,
as substrate
for nitrogen-fixing
the bryometer
has spread
around
the world,
but has been
organisms,
are important
to the forestry
industry.
In
of especial value in Europe,
where it has also been known
Sphagnum,
and probably
other
taxa as well, three types
as a moss bag.
In Finland,
A. Makinen
(unpubl.)
used
Hy/ocomium
splendens
of
nitrogen-fixing
associations
exist:
epiphytic
moss
bags
to monitor
heavy
Cyanobacteria,
intracellular
Cyanobacteria,
and
metal s around
a coal-fired
plant.
D. R. Crump
and
(1980)
have
nitrogen-fixing
bacteria
(U. Granhall
and
H. Selander
P. J. Barlow
likewise
used the method
to
1973;
U. Granhall
1976).
Nitrogen-
and A. V. Hofston
assess lead uptake.
fixing
Cyanobacteria
of bryophyte
species
also provide
growth
enhancement
for oil-seed
rape,
the supply
plant
1990).
for canola
oil (D. L. N. Rao and R. G. Bums
S02 and Acid Rain
While North
Americans
have apparently
not adopted
the
Pollution
Studies
bryometer
per
se, they
began
using
bryophytes
for
In
1963,
A. G. Gordon
monitoring
rełatively
early.
and
Bryophytes
have
played
a major
role
in monitoring
E. Gorham
published
what
seems to be the first North
changes
in the Earth's
atmosphere.
Working
in Japan,
American
studyon
the effects
of pollutants
on mosses,
H. Taoda
(1973, 1975, 1976)
developed
a
bryometer,
a
examining
a site suffering
from S02 emissions
at about
100,000
1949
to
1960.
bag of mosses that respond
in predictable
ways to various
tons
per
year
from
Using
levels of air pollution.
By exposing
a variety
of mosses
transects
radiating
from the source,
they found that the
~
------------------~c==------
~~~~~~_=~
.~~__-------------------
ECONOMIC
AND ETHNIC
USES
17
first mosses to appear with increasing distance from the
source, namely the tolerant
Dicranella heteromalla
and
Pohlia nutans,
were at the bases of trees.
Appreciation of mo sses as reliable indicators has
grown (T. H. Nash and E. H. Nash 1974; O. L. Gilbert
1989). Gilbert (1967, 1968) found that SOa could limit
distribution, reproductive success, and capsule formation
in mosses. In 1969, he published the successful use of
Grimmia pu/vinata
as an S02 indicator in England.
Others folIowed with similar applications of other
bryophytes in Europe (5. Winkler 1976) and North
America (M. B. Stefan and E. D. Rudolph 1979).
As monitoring studies continued, researchers
developed a list of tolerant and intolerant species that
could be used as indicators. In Japan, H. Taoda (1972)
used epiphytic species to assess pollution impact in the
city of Tokyo. He divided the city into five zones, based
on pollution intensity, and listed four groups of
bryophytes (both mosses and liverworts) in order of
increasing sensitivity to 502: (1)
Glyphomitrium
b umillium, Hypnum yokohamae;
(2)
Entodon
compressus,
H.
plumaeforme, Sematophyllum subhumile,
Lejeunea punctiformis;
(3)
Aulacopilum [aponicum,
Bryum argenteum, Fabronia matsumurae, Venturiella
sinensis;
(4)
Haplohymenium sieboldii, Herpetineuron
tocceae, Trocholejeunea sandvicensis, Frullania
muscicola.
Later, Taoda (1980) used three liverworts
(Conocephalum supradecornpositum, Lunularia cruciata,
Marchantia polymorpha)
to assess the degree of
urbanization in Chiba city near Tokyo. In Europe,
K. Tamm (1984) used epiphytes, and these naturai
assemblages became quite popular as a means of assessing
air pollution.
Mosses exposed to S02 fumigation exhibit reductions
in coverage. However, it is difficult to determine if the
damage is due directly to the sulfur dioxide or if it is the
result of the ultimate formation of sulfuric acid. When
S02 dissolves in water, it ultimately forms sulfuric acid,
which dissociates to form free hydrogen ions, making
the water acid. In the celi, these hydro gen ions can replace
the magnesium of the chlorophyll molecule, destroying
it. Mosses that are tolerant of an acid environment must
have a means of protecting their chlorophyll from that
degradation or of preventing the dissociation. For
example, some mosses (e.g.
Dicranoweisia)
change
503,2 into a harmless sulfate (504'2) salt (W.J. Syratt and
P. J. Wanstall 1969).
pine
iPinus banksiana)
forests (G. Raeymaekers 1987).
Pleurozium schreberi
grew faster and increased in cover
when sprayed with water acidified to pH 4.5. In fact,
habitats of
P. schreberi
in nature ten d to be rather acid.
However, at pH 3.5, its growth and chlorophyll eontent
we re reduced and capsule production decreased.
Similarly, in boreal forests
Hylocomium splendens
and
Ptilium crista-castrensis
can replace the somewhat
pollution-sensitive
Pleurozium schreberi
when S02 stress
increases, but doser to the pollution source these species
disappear as well (W. E. Winner andJ. D. Bewley 1978).
A pH as low as 3.5 is not uncommon in acid fog.
While acid rain may favor some bryophytes, acid fog
can be more damaging. In areas like the California coast,
Isle Royale National Park, or most parts of Great Britain,
severe damage can occur during the frequent fogs because
tiny droplets of water may have a high sulfur content,
often resulting in very low pH. When these droplets rest
on one-cell-thick bryophyte leaves, the high acid eontent
can readily affect the
cell's
interior.
Not oni y can bryophytes serve as warning systems,
but they can protect the nutrients and roots beneath them.
By intercepting sulfate ions, they prevent formation of
sulfuric
acid that
contributes
to leaching
valuable
nutrients
from soil (W. E. Winner et al. 1978).
This
benefits not only mosses, but tracheopytes
that depend
on soil nutrients.
During atmospheric precipitation episodes, bryophytes
serve as filters before water reaches the soil, trapping
dissolved pollutants washed from trees. Mosses exposed
to long, dry periods usually are not damaged by S02
during those dry periods, but S02 dissolved in rain or
fog will readily damage rehydrating bryophytes. This is
due to damaged membranes that now readily admit acidic
water (resuIting from dissolved S02), which in tum easily
dissolves the more soluble celi contents and leaches them
out of the leaf. Loss of very soluble potassium and
magnesium quickly occurs, and the moss becomes pale,
an easily observed symptom of damage. Without
magnesium, the damaged chlorophyll cannot be repaired.
Bioindicators of Heavy MetaIs in Air
Pollution
The First European Congress on the Influence of Air
Pollution on Plants and Animals strongly recommended
the use of cryptogamic epiphytes as biological pollution
indicators (O. L. Gilbert 1969). The Europeans were
among the first to practice this recommendation. There,
bryophytes have been used to monitor airborne pollution
caused by emissions from factories. In 1981,
J.
Maschke
cited countries throughout the industrialized world where
bryophytes were used as indicator species. Further
evidence supports the contention that absence of epiphytic
High chlorophyll
concentration
seems also to help protect this moss.
Since different species have different sensitivities to
contaminants, a change in species composition can be
indicative of changes in atmospheric conditions. In some
areas, the acidification of bark from acid rain has resulted
in the growth on bark of species that are normally
confined to acid rocks (A. J. Sharp, pers. comm.).
Acid rain, resulting from S02 emissions, can actually
improve conditions for
Pleurozium schreberi
in some Jack
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