Conclusions

The present investigation represents an attempt to characterize the
impact of air pollutants on a total ecosystem. More importantly, it is
the first to attempt to generate methods to predict bioenvironmental
effects of air pollution before damage is sustained. In the past, most
air pollution field research has dealt almost exclusively with direct
acute effects on vegetation. It is expected that complex changes in
ecosystem dynamics as a function of relatively long term, chronic pollu-
tion challenge will be observed. By studying a rather broad range of
interacting variables, we hope to isolate some as sensitive and reliable
measures of air pollution impact.

The approach envisioned requires (1) the use of reasonably compre-
hensive models of component populations of the ecosystem; (2) the use of
appropriately structured field or laboratory experiments; and (3) evalu-
ation of physiologic and biochemical functions that may serve as specific
indicators of air pollution stress. The study will establish one part
of the cost/benefit matrix that will provide for the normalization of
environmental impact information.

1


Period of Investigation

The span of field site activity will be three years with the
months of April through October being devoted to major on-site activities.
A minimum of three years is needed for the field phase of the investi-
gation because it is necessary to measure the normal cycling and variation
through time and space of the ecosystem and also to look for large,
random effects that might otherwise be viewed as possible functions of
pollution.

Furthermore, reproductive rates and annual cycles of plants and animals
can be expected to be affected by the pollution stresses. Even provis-
jonal assessment of such effects in annually breeding populations requires
information spanning 2-3 generations. A fourth year will be required to
complete data evaluation, to write terminal data summaries and reports,
and to establish formal guidelines for the assessment of air pollution
impact from coal-fired power plants.


20.

ai.

Woodwell, G. M. 1970. "Effects of Pollution on the Structure and
Physiology of Ecosystems." Science 168:429-433.

Woodwell, G. M. 1968. "Effects of Chronic Gamma Irradiation on

Plant Communities."

Quart. Rev. Biol. 43:42-55.

19


CONTENTS

Abstract
Sections
I Introduction

Southwest Energy Study

Tennessee Valley Authority Studies
La Cygne Power Plant Studies
Other Investigations

Il Outline
Criteria for Damage to the Environment
Air Quality Measurement
Remote Sensing

III Conclusions

IV Acknowledgements

v References

Rationale

Period of Investigation

on nunepn

12
13
14

15
16
17


ACKNOWLEDGEMENTS

The authors wish to thank the following members of the National
Ecological Research Laboratory who have actively participated in design-
jing the bioenvironmental effects program on which the present paper is
based: Denis Body, Paul Botts, Jeff Lee, Bruce Lighthart, Jim Miller,

Larry Male, and Art Vallier.

16


10.

V1.

12.

13.

14.

15.

16.

18.

19,

Tingey, D. T., R. A. Reinert, J. A. Dunning, and W. W. Heck. (In
Press). “Foliar Injury, Responses of Eleven Plant Species to
Ozone/Sulfur Dioxide Mixtures." Atmos. Environ.

Tingey, D. T., R. A. Reinert, J. A. Dunning, and W. W. Heck. 1971.
“Vegetation Injury from the Interaction of Nitrogen Dioxide and

Sulfur Dioxide." Phytopathology 61(12):1506-1511.

"Analysis of Structure, Function, and Utilization of Grassland
Ecosystems." Colorado State University, 1971.

"Southwest Energy Study - An Evaluation of Coal-Fired Electric
Power Generation in the Southwest," U.S. Department of Interior,
Federal Task Force, Study Management Team, 1971.

Private Communication.

Private Communication.

Private Communication

Private Communication.

Winget, Robert N. 1971. "Progress Report No. 4, Huntington Canyon
Project Aquatic Environmental Impact Study."

Woodwell, G. M. 1962. “Effects of Ionizing Radiation on Terrestrial
Ecosystems." Science, 138:572-577.

Woodwell, G. M. 1967. "Radiation and the Patterns of Nature.”
Science, 158:461-470.

18


In addition to air quality monitoring (see below), the following
abiotic factors should be measured continuously or at frequent intervals:

Time

Precipitation

Relative humidity

Air temperature (at varying heights above ground)
Soil temperature (at several depths)

Wind speed

Total radiation

Net radiation

Soil water (2 depths)

Soil heat flux

ws rah Ooandg sa»

Air Quality Measurements

The NERL mobile air quality laboratory in Montana will measure S05,
NO/NO,/NO,, ozone, total and detailed hydrocarbons, CO, methane, and
meteorological variables continuously. A second mobile laboratory will
be located near Colstrip to characterize the aerosols in the vicinity of
the power plant. The two lab trailers together will allow the character-
ization of the gases and aerosols in the vicinity of the power plant.
This will provide the basis for comparative evaluations during the
operating years. The present schedule allows for the gas monitoring
trailer to be located in Colstrip, Montana, from April through October
each year. The aerosol trailer will be located in Montana for periods
up to two months during the growing season each year.

Data assimilation and recording will be effected by a Monitoring
Laboratories Data Acquisition System. The data are assimilated and
’ printed via teletype into one information package. The system retains

13


effects of pollution on the growths of timber stands. The sulfur content
of soil, litter, and vegetation is being monitored. Prior to the plant
going on line, the Tennessee Valley Authority had collected three years
of preoperational (background) data on local flora and fauna for before
and after comparison purposes.

The Tennessee Valley Authority is also conducting forestry surveil-
lance activities in the vicinity of the Widows Creek Steam Plant. Their
objective is to determine the extent to which operation of the steam
plant has affected the appearance, growth, and survival of local timber
stands. In addition, they are testing the feasibility of applying
remote sensing techniques to the detection of SO, injury.

The Tennessee Valley Authority has developed a substantial amount
of experience in operational atmospheric monitoring. Precipitation is
sampled biweekly and analyzed for volume, pH, and content of sulfate,
nitrate, ammonia, calcium, magnesium and strong acid. Samplers collect
information on volume of precipitation, pH, and sulfate content. Sulfate
aerosol collectors sample weekly and analyze for suspended particulates
and sulfates.

La Cygne Power Plant Study

The La Cygne, Kansas Coal-fired Power Plant Study is sponsored by
the Environmental Protection Agency and is being conducted by Wichita
State University. The terrestrial environment, including vegetation,
animals, and soils is being investigated. The objective of the program
is to evaluate the influence of stack emissions from a new coal-fired
electric generating plant on the surrounding ruralagricultural and old
field communities. Sampling for trace elements around the power source
has been in progress since 1972. The investigators are attempting to
(1) monitor pollutant dispersal; (2) determine pollutant concentrations


This capability may be realized if research programs are designed
to integrate process studies of the soil, animal, and vegetation compo-
nents of the ecosystem. Before beginning these programs, reviews of
existing research are necessary. A review of laboratory process studies
and field ecosystem programs allows us to begin to piece together such
an integrated research approach. For example, the Department of Agri-
culture publication on the effects of air pollutants on domestic animals?
lists results of laboratory investigations. Numerous publications by
the academic community and EPA have characterized the effects of pollution
on vegetation. 4-19 There is a paucity of laboratory data available for
air pollutants affecting soil microfauna and flora. It is the synthesis
of these process studies that ultimately leads toward achieving the
total systems approach. |!

Few air pollution field studies have attempted to combine soil,
vegetation and animal research into an integrated program. The South-
west Energy study, !2 the La Cygne, Kansas, Coal-fired Power Plant
Study, !3 the Tennessee Valley Authority Cumberland!4 and Widows creek!®
Coal-fired Power Plant Studies represent research efforts that have
attempted to combine the various components of the ecosystem (air,
water, soil, vegetation, and animal) into an integrated biological

program.

Southwest Energy Stu

The Southwest Energy task force was established in May 1971, to
undertake a study of electrical energy generation and transmission in
the Southwestern United States. The objectives and scope of the project
were to evaluate (1) the importance of the existing natural resources,
aesthetic factors, cultural patterns and economic needs of the area; (2)
the quantitative long-term need for power in the southwest, (3) the


INTRODUCTION

The Nation is presently faced with a series of problems concerning
the production, distribution and consumption of fossil fuel energy
sources. Because of great abundance at relatively low cost, the administra-
tion's commitment to energy self sufficiency by 1980, and other factors,
jit is clear that the United States is moving toward an economy based on
coal as the primary fossil fuel resource. ! Indeed, by early 1974, there
were approximately 970 fossil fueled power plants in operation nationwide,
with a total generating capacity of some 302,000 megawatts. Apportion-
ment of this generating capacity by fossil fuel source is approximately:
55 percent coal-fired, 17 percent oil-fired, and 28 percent gas-fired.

The decisions that will ultimately resolve the environmental and
economic issues we face must be made with full knowledge of the con-
straints imposed by the need to minimize environmental impacts associated
with energy production and utilization. The present paper summarizes
the National Ecological Research Laboratory's (NERL) approach to the
solution of one portion of this problem set. NERL, in cooperation with
other Federal agencies, the State of Montana, and several universities,
has initiated a research program designed to assess the impact of coal-
fired power plants on a grassland ecosystem and to develop a valid and
effective environmental impact assessment protocol.

Preliminary to the development of this program, a thorough review
of the relevant biological and air pollution literature has led us to
the conclusion that most investigations of the effects of air pollution
from coal conversion facilities are largely site specific and have,
furthermore, only retrospective value. Clearly, a predictive capability
is required if we are to make rational decisions regarding the siting of
such facilities.


the information and provides teletype printouts of 1 hour, 4 hour, 8
hour, or 24 hour averages.

The air quality data registered by the two EPA mobile laboratories
will be supplemented by similar data on gases from two mobile air quality
laboratories operated by the State of Montana. Refrigerated air samples
collected daily from approximately ten study sites, will also be analyzed
for major pollutants. The structure of this air quality monitoring
network was determined largely on the basis of diffusion modeling,
topography, land use, and by biological, fiscal, and land ownership
constraints. While this system is far from ideal, we feel that it is
adequate to establish annual and diurnal patterns and variance in pollu-
tion levels, pollution gradients, and their relationship to biological

parameters.

Remote Sensing

Whereas we are primarily concerned with effects of air pollution,
secondary and potentially confounding impacts from diverse sources
invariably occur in association with coal mining, conversion, and combus-
tion for delivery as electrical energy. Unless we are able to identify
these sources and magnitudes of their effects, we may be unable to fully
identify and isolate the effects of air pollution per se. Furthermore,
control strategies can be set only if we have the capacity to investigate
effects over large areas and at considerable distances from active mines
and their associated power plants.

Remote sensing can thus be employed as one possible tool to inven-
tory some of the major ecosystem resources and to provide information on
the larger scale ecosystem changes that occur during and prior to the

period of study.

14


soil; and (10) establishment of a specialized work force of government
employees to assess environmental problems associated with future south-

west power plants.

Based on the assessment of the various working groups, several
agency and university groups initiated research problems to assess the
impact of coal-fired power plants on the southwest environment. The
Department of Biological sciences, Northern Arizona University, !® initi-
ated several studies to assess the effects of power plant activities on
biota. These studies are located near the proposed Kaiparowits and
Navajo generating stations. In addition, the Center for Environmental
Studies at Brigham Young University!” is conducting an aquatic and
environmental impact study at the Huntington Canyon project, Utah. The
research will determine the effects of Huntington Canyon power plant and
Electric Lake on the aquatic environment of Huntington Canyon and its

drainage system.

Tennessee Valley Authority Studies

The Tennessee Valley Authority has mounted a biological program to
assess the effects of coal producing activities in several locations.
A 2600 megawatt power plant located on the bank of the Cumberland River,
will emit approximately 1600 tons/day S05 into the atmosphere when
operating at normal full load. The Tennessee Valley Authority has
identified the Cumberland Steam Plant as an SO, source that could impact
vegetation and animals in the vicinity of the power plant and have
selected it for extended study. Vegetation surveys, timber stand growth
and conditioning surveys, soil surveys, total atmospheric S05 loading
surveys, and a lichen survey are being performed in the vicinity of the
power source. The objectives of the program are to sample the major
pathways of sulfur decomposition and movement in the environment (precipi-
tation, sedimentation, and absorption by vegetation) and to assess the


BIBLIOGRAPHIC DATA |} Report No. 2
SHEET EPA-660/3-74-011

3. Recipient's Accession No.

4. Title and Subtitle The Bigenvironmental Impact of Air Pollution from
Fossil-Fuel Power Plants

© Report Date

August 1974

6.

7. Author(s) . .
: flational Ecological Research Laboratory

8. Performing Organization Rept.
jo.

9. Performing Organization Name and Address

National Ecological Research Laboratory
Environmental Protection Agency
Corvallis, OR 97330

10. Project/Task/Work Unit No.
PE 1AA006 21 BCI 02

V1. Contract/Grant No.

12. Sponsoring Organization Name and Address

same

13. Type of Report & Period
Covered

Final Report

4,

15. Supplementary Notes

16, Abstracts

The body of information presented in this paper is directed to environmental
scientists and engineers and to those land managers who will be involved in
assessing the effects of energy conversion activities on the environment.

A prototype investigation of the bioenvironmental effects of air pollution challenge
from coal-conversion facilities is summarized. Objectives, rationale, and the
overall design of this research are presented. Recommendations regarding the
selection of suitable criteria of environmental damage are also made. The authors
hope this paper will serve to stimulate thought and discussion that will lead to

a predictive capability in the area of bioenvironmental impact assessment.

17. Key Words and Document Analysis. 17a. Descriptors
ecosystem dynamics
ecosystem modelling .
criteria for ecological damage
remote sensing
air pollution
fossil fuel energy conversion
pollution impact assessment -

17b. Identifiers/Open-Ended Terms

ecological impact assessment
ecosystem dynamics
energy conversion

17e. COSATI Field/Group

Report)

18. Availability Statement 19. Security Class (This_ 21. Br of Pages

INCLASS)
Wo Secig Cis Chis 22. Price

age
UNCLASSIFIED,

FORM NTIS-35 (REV. 3-72)

USCOMM-DC 14952-P72





Based on this comprehensive investigation, we hope to generate a
defensible, sensitive, and relatively simple program that may be used in
other grassland situations to monitor, evaluate, and predict bioenviron-
mental effects of air pollution from fossil fuel conversion processes.
We envision an evolving program that will allow managers to gradually
refine cost-benefit determinations in making decisions concerning site-
selection and air pollution control of coal-conversion facilities.

Rationale

In addition to the "simple" direct effects of air pollutants that
have been reported from experimental studies of natural systems, we may
expect to observe complex changes in ecosystem dynamics as a function of
pollution challenge. We know that insults to the environment from
rather diverse sources (toxic substances, pesticides, radiation, disease,
adverse climate) produce a similar array of effects at the community
level in spite of very different effects on individual organisms studied
under experimental conditions. The response mechanisms may be complex,
but they often result in a "reversal" of succession or a simplification
of ecosystem structure, a reduction in the ratio of photosynthesis to
respiration, and a reduction in species diversity at more than one
trophic level; this may include the elimination of certain species
(e.g., in grassland, usually rare, but characteristic species). Effects
may be temporary and reversible (i.e., the system adapts) or chronic and
cumulative. In any case, if a coal-fired power plant has a measureable
impact on the environment, there is every reason to believe that it will
be registered as a loss of community structure. Both plant and animal
diversity and energy transfer between and within trophic levels are
measures of community structure. Furthermore, these functions may be
regarded as important ecosystem resources. It is our view that the
immediate population-level effects of an environmental stressor may
result from differential impairment of competitive ability. At the


in plants; (3) and to monitor trace elements in animals and soils. The
program has not stressed community or ecosystem dynamics.

Other Investigations

In addition to the activities mentioned above, there are several
research programs that deal with the interpretation of basic processes
that occur in a variety of ecosystems. The International Biological
Program (IBP) sponsored by the National Science Foundation for the past
several years, has investigated a number of basic biological processes
such as carbon fixation, photosynthate primary and secondary transloca-
tion, turnover of organic matter, recycling of nutrients and trace
elements and the development of ecosystem models. Results from the
deciduous forest, grassland, desert, and coniferous forest biome projects
in addition to other major programs !8-21 may supply basic information
that will support applied research directed to the assessment of the

effects of pollutants on whole ecosystems.

An Approach to the Study of Impact Assessment

The following discussion presents an overview of NERL's recently-
initiated coal-fired power plant project. The broad objective of this
program is to measure and predict change in a grassland ecosystem as a
function of meaningful environmental parameters including air pollutants.
We are concerned not only with the stability of ecosystem organization
in relation to ambient conditions, but also with the predictability and
reproducability of changes that do occur. Insight into the mechanisms
of dynamic-structural responses to air pollution challenge is also
sought. It is particularly important to identify the subsystem functions
that contribute to ecosystem regulation and the mechanisms whereby such

regulation is effected.


effects of incremental power development on quality of air, land, water,
wildlife and human needs; (4) the environmental tolerances of the area
for power development; and (5) the alternatives available for achieving
optimum development with tolerable impact.

Working groups were selected to investigate (1) power development
and economic effects, (2) water supply, (3) water and air pollution, (4)
water resources monitoring, (5) atmospheric studies, (6) land use, (7)
cultural, economic and social factors, (8) biota, (9) recreation and
aesthetics, (10) coal resources, (11) coal production methods and tech-
niques, and (12) alternative uses of Colorado River Basin coals. The
biota work group evaluated the effect of coal-fired power plant activities
upon vegetation within the southwest energy area and upon a number of
animal species that inhabit the area. Emphasis was placed on biotic
effects. The analysis of stack emissions on animals was based primarily
on a review of extant scientific literature. Analysis of the effects of
stack emissions on plants was based primarily on American sources of

literature and on current research within Epa, 4710

The biotic committee recommended (1) a short-term review of liter-
ature on the biotic effects of air pollution (2) a mass balance study of
trace elements, including heavy metals at the Four Corners Power Plant;
(3) a short-term study of vegetation in areas likely to be damaged by
stack emissions; (4) short-term aquatic studies to determine basic
indicator organisms and food chains; (5) Monitoring of vegetation in
the vicinity of power plants to determine the effects of sulphates,
fluorides, and trace elements; (6) aquatic monitoring and fishery
research studies of streams, natural lakes, and reservoirs; (7) terres-
trial and wildlife monitoring of animals and their habitat; (8) the
study of physical and chemical characteristics of precipitation downwind
from power plants; (9) determination of radiation levels in the ambient
air, aquatic and terrestrial organisms, water, bottom sediments, and


REFERENCES

Osburn, E. F. 1974. "Coal and the Present Energy Situation."
Science 183 (4124): 477-481.

"National Public Hearings on Power Plant Compliance with Sulfur
Oxide Pollution Regulations." U.S. Environmental Protection Agency
Washington, D.C. January, 1974, 107 pp.

“Air Pollutants Affecting the Performance of Domestic Animals -A
Literature Review." U.S. Dept. of Agriculture, Agricultural Research
Service, Agriculture Handbook No. 380, 1970.

“Air Quality Criteria for Sulfur Oxides." U.S. Dept. of Health,
Education, and Welfare, Public Health Service, PHS-Pub.-AP-50,
1969.

Menser, H. A., and H. E. Heggestad. 1966. "Ozone and Sulfur
Dioxide Synergism: Injury to Tobacco Plants." Science. 153:424-
425.

Tingey, D. T., W. W. Heck, and R. A. Reinert. 1971. “Effect of
Low Concentrations of Ozone and Sulfur Dioxide on Foliage, Growth,
and Yield of Radish. J. Amer. Soc. Hort. Sci. 96(3): 369-371.

Reinert, R. A., 0. T. Tingey, W. W. Heck, and C. Wickliff. 1969.
"Tobacco Growth Influenced by Low Concentration of Sulfur Dioxide
and Ozone." Agron. Abstr. 61:34.

Brandt, C. S., and W. W. Heck. 1968. "Effects of Air Pollutants

on Vegetation." In: Air Pollution, 2nd Ed., Vol. I, Stern, A. C.
(ed.). New York, Academic Press pp. 401-443.

7


ABSTRACT

The body of information presented in this paper is directed to
environmental scientists and engineers and to those land managers who
will be involved in assessing the effects of energy conversion activities
on the environment. A prototype investigation of the bioenvironmental
effects of air pollution challenge from coal-conversion facilities is
summarized. Objectives, rationale, and the overall design of this
research are presented. Recommendations regarding the selection of
suitable criteria of environmental damage are also made. The authors
hope that this paper will serve to stimulate thought and discussion that
will lead to a predictive capability in the area of bioenvironmental

impact assessment.

ii


OUTLINE

The research plan is outlined below; some of the major components
are discussed subsequently:

1. Field Investigation

A. Temporal and spatial quantitative inventory of components of

the study area, with particular focus on annual cycle phenomena of

key species.

B. Meteorological measurements to support the modeling and
experimental air pollution research efforts.

C. Development of remote sensing as a tool for detecting effects
of air pollutant challenge on the ecosystem.

D0. Measurement of loss of inventory attributed to strip mining,
power lines, human activity, water use, and other potentially
confounding influences (e.g., pesticides, disease, population
cycling).

II. Air Pollution Experiments

A. Experimentally controlled air pollution of spatial segments of
an ecosystem.

B. Detailed measurement of biological structure and function,
including energy flow, nutrient cycling and species condition,
composition, and diversity during and following air pollution
stress.

10


Criteria for Damage to the Environment

There is no firm evidence regarding the sensitivity and reliability
of criteria that might be employed to assess damage to a grassland
ecosystem at relatively low chronic levels of pollution from coal-fired
power plants. Nevertheless, a suitable criterion must have several of
the following characteristics: (1) relatively low cost of measurement;
(2) standard methods for measurement and assessment; (3) specificity;
(4) potential for use in prediction; (5) stable and relatively noise-
free response; (6) a potential for yielding results in a time frame of a
year or less; (7) a potential for retrospective evaluation; (8) be
suitable for validation in subsequent years or at other sites; and (9)
reasonable sensitivity to air pollutants.

Even in a comprehensive investigation, extensive studies of a large
array of species or processes is not possible. Considerable research is
required to identify the specific parameters that will give an adequate,
sensitive measure of air pollution to a grassland ecosystem or components
thereof. Broad categories of important functions that should be investi-
gated include: (1) changes in productivity or biomass of ecosystem
compartments; (2) changes in life cycle and population dynamic functions
of "key" taxa. (3) Changes in community structure or diversity; (4)
changes in nutrient cycling; (5) sublethal biochemical or physiological
changes in individuals or compartments; (6) behavioral changes in mobile
organisms; and (7) changes in reproductive patterns.

If we are to assess and interpret the effects of air quality on
natural ecosystems, it is essential that we understand also the wide
range of abiotic factors (e.g., weather, geography, insolation, hydrology)
that influence the dynamics of the living components of the ecosystem.
Optimum production, the maintenance of stability and diversity and other
desirable properties of ecosystems all depend upon a variety of abiotic

factors.

12


EPA-660/ 3-74-011
August 1974

THE BIOENVIRONMENTAL IMPACT OF AIR POLLUTION
FROM FOSSIL-FUEL POWER PLANTS

by

National Ecological Research Laboratory
National Environmental Research Center
Corvallis, Oregon 97330

Roap/Task 21BCI-02
Program Element 1AA006

NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330


RESEARCH REPORTING SERIES

Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:

1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research

4. Environmental Monitoring

5. Socioeconomic Environmental Studies

This report has been assigned to the ECOLOGICAL
RESEARCH series. This series describes research
on the effects of pollution on humans, plant and
animal species, and materials. Problems are
assessed for their long- and short-term
influences. Investigations include formaticn,
transport, and pathway studies to determine the
fate of pollutants and their effects. This work
provides the technical basis for setting standards
to minimize undesirable changes in living
organisms in the aquatic, terrestrial and
atmospheric environments.

EPA REVIEW NOTICE *

The Office of Research and Development has reviewed this
report and approved its publication. Mention of trade names
or commercial products does not constitute endorsement or
recommendation for use.


relatively low pollution levels anticipated in our investigation, we may
expect to find prediposing and subclinical effects that will be impos-
sible to detect in the absence of appropriate population dynamic,
biochemical, and physiologic information.

Effects need not be mediated by alterations in food chains or
energy flow. Food chains and mass and energy flow patterns, of course,
will be affected, although possibly secondarily, whenever population
adjustments occur. For example, an environmental stressant may alter
the physiology or behavior of the individuals that comprise a
population. These alterations are ultimately reflected in altered
survival, reproduction and/or emigration rates. Such effects may be
subtle and difficult to relate to the specific stressor. In the real
world, numerous stressors are operating in complex ways and with various
lag times; these tend to confound the results of any field evaluation of
a single stressor. The end result of the response of a community to a
continuing environmental stress is a readjustment of the component
populations (plant and animal) at a new state of dynamic equilibrium.

It is not possible to predict with any confidence, either the adjustments
and mechanisms most importantly involved or the nature of the final
population levels or the balance that will be reached. By studying a
rather broad range of interacting variables and, in particular, by an
intensive study of certain populations, some may be isolated as sensitive
and reliable measures of air pollution. The approach envisioned requires
(1) the use of reasonably comprehensive models of component populations
of the ecosystem; (2) the use of appropriately structured field and
laboratory experiments; and (3) evaluation of physiologic and biochemical
functions that may serve as specific indicators (or even predictors) of

air pollution stress.


Ill.

Iv.

Laboratory Experiments

A. Measurement and evaluation of physiologic, biochemical, and
behavioral mechanisms of response to air pollution challenge.

B. Precise measurement of parameters that support dynamic models.

C. Experiments designed to test whether changes observed in
experimental study plots can be attributed to air pollutant
stress.

D. Secondary stressor experiments (e.g. disease, temperature
stress, water stress, non-specific stress).

E. Experiments designed to test field-generated hypotheses.

Modeling

A. Use of an ecosystem level model to describe and predict effects
of air pollutant challenge.

B. Use of models to help design experiments.

C. Use of models to help disentangle pollutant effects from
natural variation and system dynamics.

D. Meteorological and dispersion modeling to describe the mode of

entry of pollutant into the ecosystem and its time and space
distribution and concentration.

11