Abstracts of Papers - Harvard Forest - Harvard University

Symposium: Assessing Air Quality with
Lichens and Bryophytes-Part I
BRYOLOGICAL AND LICHENOLOGICAL SECTION
INTRODUCTION - Parts I and II
This symposium will address various methods of
using lichens and bryophytes in air quality monitoring.
Papers will include the topics of floristic
analysis, mapping of sensitive species, statistical
analysis of quantitative data, correlating
fumigation studies with physiological effects and
with field studies, trace element analysis, species
variability with respect to air pollution and the
ecological importance of lichens and bryophytes.
These papers will summarize techniques presently
in use and evaluate their reliability and usefulness
in assessing air pollution damage.
Organized by Clifford Wetmore, University of Minnesota,
St. Paul, MN and James Bennett, National
Park Service, Denver, CO.
BENNETT, JAMES P. National Park Service, Air
Quality Division, Box 25287, Denver, CO 80225.
- The air pollution importance of non-vascular
plants to the National Park Service.
The National Park Service (NPS) has a mandate to
protect the biological resources of the national
parks from the effects of air pollution. Under
Clean Air Act regulations, the NPS has authority
to determine whether or not higher than ambient
S02 concentrations will cause adverse impacts on
lichens and mosses in the parks. The NPS consid-
ers non-vascular plants as integral components
of natural ecosystems because of their ecological
importance as colonizers, nitrogen-fixers, food
sources and soil stabilizers. Their position at
the base of many food chains makes their role of
primary importance.
Lichen sensitivity to S02 and heavy metals
is well known. Several national parks are cur-
rently experiencing elevated S02 concentrations,
some high enough to cause effects on lichens and
mosses. The NPS has initiated six projects on
lichens and mosses and air pollution, including
floristic studies, sulfur baseline sampling,
heavy metal sampling, and ecological community
analyses. These studies will enable NPS to de-
termine future adverse impacts on non-vascular
plants in the parks.
NASH III, THOMAS H. Department of Botany
& Microbiology, Arizona State University,
Tempe, AZ 85287 - Correlating fumigation
studies with field effects.
Differential tolerance of different lichens
to the environment of cities and isolated
pollution sources is well established. It
is frequently assumed that these patterns
reflect differential sensitivity to sulfur
dioxide and/or other air pollutants. This
assumption may be false or only partially
true because lichens may well respond to
alteration of other environmental factors.
Fumigation studies with controlled levels
of air pollutants provides a means for ex-
perimentally establishing whether lichens
are in fact sensitive to air pollutants.
It is important that both realistic exposure
durations and realistic pollutant concentra-
tion levels be employed. Furthermore, ex-
posure conditions must be chosen to reflect
conditions characteristic of the environment
where th lichens occur naturally. The fumi-
gation literature is critically examined
with respect to these caveats and examples
are given where the hypothesis that lichens
are sensitive to air pollutants is both
supported and not supported.
NIEBOER, EVERT* and KEN A. KERSHAW, Departments of
Biochemistry and Biology, McMaster University,
Hamilton, Ontario, Canada, L8N 3Z5.
- Ecological Implications of Laboratory Toxicity
and Related Photosynthetic Studies.
It will be demonstrated that a large proportion of
the elemental content of lichens is the result of
particulate trapping within the interstitial spaces
of the thallus. A strong dependence on surface
morphology can be illustrated for this phenomenon.
Such accumulation may be expected to be relatively
innocuous. Recent studies will be reviewed that
show that the largely passive extracellular uptake
of metal ions can be either protective or deleteri-
ous, depending on the chemical reactivity of the
metal cation. Dissection studies are reported that
indicate that metal-ion binding occurs to both the
algal zone and fungal medulla, and that the uptake
capacities of these zones, as well as the total
uptake, are strongly lichen species dependent. Work
with the uranyl ion further illustrates the import-
ance of chemical speciation. And finally, toxic
effects of ion absorption and SO2 exposure are shown
to be ameliorated by the mineral status of the
thallus (high Ca2+, Mg2+, K+ contents), by uptake
inhibition (phosphate competing with arsenate; metal
-ion rivalry), and high photosynthetic capacities.
In this context, laboratory studies that simulate
seasonal variations in photosynthetic capacities are
summarized. In addition to species susceptibility,
these observations imply a substrate and seasonal
dependence of the toxicity to lichens of environmen-
tal pollutants. Inferences for the use of lichens
as monitors of environmental pollution will be
pointed out.
PUCKETT, KEITH.* J. & SEDIGHEH SANG.
Atmospheric Environment Service,
Environment Canada, 4905 Dufferin St.,
Downsview, Ontario, M3H 5T4.
-Trace element mapping with lichens and
bryophytes.
Since lichens and bryophytes are known to
obtain and accumulate metal pollutants as
well as their required nutrients from the
atmosphere (either from rainfall or by
impaction and sedimentation of airborne
dust), they have been employed as
biological indicators of trace element
fallout in a great number of studies. In
this paper enhanced levels of elements in
lichens and mosses were reviewed and the
usefulness of these plants for monitoring
and mapping the concentrations of
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