UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
OFFICE OF
THE ADMINISTRATOR
EPA-SAB-CASAC-91-Q10
July 23, 1991
Honorable William K, Eeilly
Administrator
U.S. Environmental Protection Agency
401 M Street, S,W.
Washington, D.C. 20460
Subject; Science Advisory Board's review of the Office of Research, and Development
draft research plan Effects of Tropospherie Ozone on Forest Trees.
Dear Mr. Reilly;
At the request of the Office of Research and Development, the Forest Research
Subcommittee of the Clean Air Scientific Advisory Committee (CASAC) reviewed a
draft research plan designed to assess the role of ozone as an anthropogenic stressor
influencing forest resources in the United States, The Subcommittee met on
December 14, 1988, in Research Triangle Park, North Carolina, Due to an oversight,
completion of the Subcommittee's report was delayed, but, after consulting with the
appropriate research program staff, we believe that the report still has utility to the
Agency, We do regret the delay.
The draft plan comprises eight research tasks tailored to meet the information
input needs of the standard setting process, including region-specific tree response
studies, investigations of the exposure dynamics for ozone, development of exposure
response functions for several species, and risk assessment. Within these tasks, there
is an explicit focus on mechanisms of action, beginning with the whole-plant
physiology of seedlings and saplings, and extending to mature trees and forest stands.
This approach is essential to provide the scientific underpinnings necessary to extend
site-specific data along spatial and temporal scales. Failure to use such an approach
to scaling and data translation has been a shortcoming of some predecessor programs.
The plan specifically addresses a highly relevant and challenging issue— welfare
effects—and its formulation recognizes that welfare effects will play a greater role in
developing ambient air quality for ozone than has heretofore been the case. The
Printed on Recycled Paper
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Clean Air Act Amendments enacted in 1990 call for a study of the criteria for
setting/revising secondary National Ambient Air Quality Standards (NAAQS), making
this aspect of the research plan assume even more significance than at the time of its
formulation.
The Subcommittee identified several concerns regarding some specific sections of
the plan, and provided several recommendations for its improvement (both described
within the body of the attached report); in the broad view however, we endorse the
proposed research plan as being a scientifically sound and defensible program to
address the influence of ozone on the nation's forest resources, as well as one that is
responsive to the needs of the Agency, We look forward to seeing the program's
activities contribute to the standard setting process.
The Committee is pleased to have had the opportunity to review the draft
document and to offer its advice. We would appreciate your response to the major
points we have raised in the report.
Dr. Roger McClellan
Chairman
Clean Air Scientific Advisory
Committee
Dr. George E, Taylor,
Chairman
Forest Research Subcommittee
ATTACHMENT
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United States Science AArtswy
Environmental BoanJ (A-101) July 19S1
Piuwc&Dii Agency
»EPA THE EFFECTS OF
TROPOSPHERIC OZONE
ON FOREST TREES
REVIEW OF THE OFFICE OF
RESEARCH AND DEVELOPMENT'S
DRAFT RESEARCH PLAN BY THE
FOREST EFFECTS
SUBCOMMITTEE OF THE CLEAN
AIR SCIENTIFIC ADVISORY
COMMITTEE
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ABSTRACT
The Forest Research Subcommittee of the Clean Air Scientific Advisory
Committee reviewed in public session the U.S. Environmental Protection Agency's
research plan: "Effects of Tropospheric Ozone on Forest Trees," Trie Subcommittee
unanimously endorses the plan as a scientifically sound program and one that is
responsive to the needs of the Agency. The plan addresses the role of welfare
effects in standard setting, and provides for parallel modeling and experimental tasks
to scale site-specific and time-specific data to regional and national concerns. The
Subcommittee offers recommendations on selected aspects of the plan, and looks
forward to the plan's products providing a unique data base which will help in
developing the secondary National Ambient Air Quality Standards for ozone.
Keywords: Ozone; forest; ambient air standards; productivity; welfare
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U.S. Environmental Protection Agency
Science Advisory Board
Clean Air Scientific Advisory Committee
Forest Research Subcommittee
Chairman
Dr. George E. Taylor, Jr,
Professor
Desert Research Institute
University of Nevada System
Members
Dr. Eileen G. Brennan
Professor Emerita, Plant Pathology
Department
Rutgers University
Dr. Jay S. Jacobson
Plant Physiologist, Boyce Thompson
Institute for Plant Research
Dr. Timothy Larson
Environmental Engineering and Science
Program, Department of Civil
Engineering
University of Washington
Dr. D. Warner North
Principal, Decision Focus Inc.
Palo Alto, California
Dr. Robert D, Rowe
Senior Vice President, RCG/Hagler,
Bailly, Inc.
Boulder, Colorado
Dr. William E. Winner
Department of General Science
Oregon State University
Science Advfeoty_BQaBi_Stelf
Mr. Samuel R Rondberg
Designated Federal Official
Science Advisory Board
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
{202} 382-2552
Mr. A. Robert Flaak
Designated Federal Official
Science Advisory Board
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
(202) 382-2552
Ms. Carolyn Osborne
Staff Secretary
Science Advisory Board
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
{202} 382-2552
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U.S. Environmental Protection Agency
Science Advisory Board
Clean Air Scientific Advisory Committee
Chairman Science Advisory Board Staff
Dr. Roger McCleilan Mr. Robert Flaak
Chemical Industry Institute Executive Secretary
of Toxicology Science Advisory Board
Research Triangle Park, N.C, Washington, D.C,
Members
Dr. Gilbert Omenn
School of Public Health and
Community Medicine
University of Washington
Seattle, Washington
Dr. Marc Schenker
Division of Occupational and
Environmental Medicine
University of California
Davis, California
Dr. Mark Utel!
Pulmonary Disease Unit
University of Rochester Medical Center
Rochester, New York
Dr. Jerome Wesolowski
Air and Industrial Hygiene^Laboratory
California Department of Health
Berkeley, California
Dr. George Wolff
General Motors Research Laboratories
Environmental Sciences Department
Warren, Michigan
Dr, Timothy Larson
Department of Civil Engineering
University of Washington
Seattle, Washington
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TABLE OF CONTENTS
1.0 EXECUTIVE SUMMARY 1
2.0 INTRODUCTION 2
3.0 RISK ASSESSMENT . 2
4.0 LINKAGES WITH OTHER RESEARCH PROGRAMS 3
5.0 MITIGATION AND ADVERSITY ,,.,»,...... 3
6.0 TIME FRAME OF RESEARCH PROGRAM . ., 4
7.0 POLICY AND TASKS 4
8.0 REGIONAL ASSESSMENT OF RESPONSES 4
9,0 INTERIM REPORT ON PROTECTION PROVIDED BY EXISTING STAN-
DARDS 5
10. SUMMARY AND CONCLUSIONS 5
HI
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1.0 EXECUTIVE SUMMARY
This report presents the formal conclusions and recommendations of the Clean Air
Scientific Advisory Committee (CASAC) review of the U.S. Environmental Protection Agency
(EPA) Research Plan: "Effects of Tropospheric Ozone on Forest Trees." The basis for these
conclusions and recommendations was the public meeting of the Forest Research
Subcommittee of CASAC, conducted on December 14, 1988, in Research Triangle Park,
North Carolina.
The Plan is a unique research program addressing the role of ozone as an anthro-
pogenic stress influencing forest resources in the United States. It comprises eight research
tasks (See Table 1) tailored
to meet the information in-
put needs of the standard
setting process. Notable
examples are the region-
specific tree response stud-
ies (Task 2), Investigations
of the exposure dynamics
for ozone (Task 6), devel-
opment of exposure res-
ponse functions for several
species (Task 7), and risk
assessment (Tasks 3 and
8). The results of this re-
search should make a major
contribution to meeting the
information needs of the Of-
fice of Air Quality Planning
and Standards (OAQPS)
and to the process of devel-
oping National Ambient Air
Quality Standards (NAAQS).
•t
EFFECTS
EXPOSURE; STUDIES: SCREENING QFSPECIES
INTERIM OZONE HA2^ ASSESSMENT
4,
TION OF TREE
SIMULATING
•£•
MECWArlSTIC
EXPOSURE DYNAMICS
RESPONSE
THE
ASSESSMENT 0P 626NE RISK T^) FOREST
SPECIE^ . • \ \ ^<;\,;r:' „.
Table 1 Ozone Forest Research Plan Tasks
The Plan's second major attribute is its explicit focus on mechanisms of action, begin-
ning with the whole-plant physiology of seedlings and saplings (Task 5} and extending to
mature trees and forest stands (Tasks 4 and 7). This approach is essential to provide the
scientific underpinnings necessary to extend site-specific data along spatial and temporal
scales. Failure to use such an approach to scaling and data translation has been a
shortcoming of some predecessor programs.
The combination of these two major features into a single interactive research plan (i.e.,
addressing the needs of the standard setting process while developing an understanding of
the mechanisms underlying a tree's response to ozone) is exemplary, in the larger context,
the Subcommittee unanimously endorses the Research Plan as being a scientifically sound
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and defensible program to address the influence of ozone on the nation's forest resources
as well as one that is responsive to the needs of the Agency. We look forward to seeing
the program's activities contribute to the standard setting process.
The Subcommittee's concerns regarding several specific features in the Plan are
described in the body of this report.
2.0 INTRODUCTION
At the request of the Office of Air Quality Planning and Standards (OAQPS), the Forest
Research Subcommittee of the Clean Air Science Advisory Committee (CASAC) reviewed the
Research Plan entitled "Effects of Tropospheric Ozone on Forest Trees," developed by the
EPA's Environmental Research Laboratory in Corvallis, Oregon. The CASAC was invited to
review and provide comment on the program because a primary goal of the proposed
research is to contribute to the standard setting process. The review was conducted on
December 14, 1988 in Research Triangle Park, North Carolina,
3.0 RISK ASSESSMENT
The inclusion of risk characterization as both interim and final tasks is commendable,
The Subcommittee recommends that characterization of risk be considered as an initial effort
as well. The objective would be to define the research needs emerging from the forest
assessment in the November 1988 draft Staff Paper ("Review of the National Ambient Air
Quality Standards for Ozone; Assessment of Scientific and Technical Information" - Chapters
IX, X, and XI) and the integrated assessment efforts currently ongoing by EPA and other
agencies on both national (National Acid Precipitation Assessment Program - NAPAP) and
regional (e.g., San Bernadino National Forest, Appalachian Crest, southeastern pine
plantations) scales. Assuming that this recommendation is enacted, the interim assessment
(Task 3) would be designed to re-evaluate the program's research needs based on the
progress achieved as outputs from Tasks 1 and 2. This evaluation could easily be
incorporated into the existing Task 1, Moreover, its inclusion would provide a more formal
methodology for scoping other efforts,
The interim assessment (Task 3) should be done quickly to determine and document the
risk assessment methodology (p. 33, point 8 of the Research Plan) and provide a preliminary
integrated analysis of selected regional areas, utilizing output from research Task's 1,2, and
7 (as noted on page 34 of the research plan). This assessment should clearly indicate the
data needs, monitoring inputs, models, and methodological developments necessary to
complete a balanced and comprehensive assessment at the end of the five year program.
Both assessments for Tasks 3 and 8 should address regional differences and policy issues
central to the role of OAQPS in the standard setting process for ozone and photochemical
oxidants.
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4.0 LINKAGES WITH OTHER RESEARCH PROGRAMS
The proposed program provides linkages (page 69) with selected other forest response
activities, including the national Forest Response Program (FRP) and the Electric Power
Research Institutes's (EPRI) "Response of Plants to Interacting Stresses," There are also
other programs in various stages of development (from proposed to completed) with which
more explicit linkages could be established to assure (1) that the planned research is
complementary; (2) that maximum exchange of pertinent information takes place; and (3)
mutual assistance is provided for recurrent program planning exercises. Of particular
importance to assessing the forest effects of ozone is air quality/aerometric research
designed specifically to characterize ozone climatology in forested landscapes; global climate -
programs in the U.S. EPA and elsewhere (e.g., biodiversity, carbon dioxide, UV-B radiation);
forest health and productivity programs being developed on a national and regional scale by
the U.S. Forest Service; and econometric analyses in existing or anticipated extensions of the
NAPAP program in risk assessment of biotic resources. Lastly, steps should be taken to
assure that the research effort benefits from the lessons learned from the EPA's Office of
Research and Development evaluation of the NAPAP's findings on the impacts of acidic
precipitation on forest resources.
5,0 MITIGATION AND ADVERSITY
In Task 7 of the plan, exposure/response functions will be developed for multiple tree
species representing most of the regional forest types in the United States. That information
is critical to develop a plan that is national in scope, and the Subcommittee endorses that
feature. At the same time, the Subcommittee expresses some concern that the results of
such functional analyses may misstate both the direction of adverse effects or the rate of
change, since natural processes and human management strategies may partially or totally
mitigate some chronic stresses. For example, due to interspecies competition, ozone
sensitive species may decline in dominance and be replaced in the canopy by more resistant
species, Species that are unaffected by ozone in exposure response studies may be more
or less sensitive under natural conditions of competition for limited resources In forest stands.
Accordingly, some anticipated long-term changes (either "positive" or "negative") in forest
resources, associated with changes in ozone levels, may not be realized. The assessment
of exposure/response functions should thus include some verification of species in natural
forest stands. Such verification would also help in defining "adverse impacts" in terms of
recreation, ecosystem stability, and commercial productivity of forest resources. Models of
mitigation strategies need to be validated by well-planned follow-up studies in such forests.
It is not clear to the Subcommittee if this aspect of longer term changes due to natural
or human intervention will be addressed. It clearly falls within the realms of modeling (Task
4) and risk assessment (Task 8). Because the risk assessment approach would require
accessing the more rigorous ecological modeling skills developed in the last decade to
address forest community dynamics (Task 4), it is recommended that these two tasks be
developed jointly.
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6.0 TIME FRAME OF RESEARCH PROGRAM
This plan presents a comprehensive and unique series of tasks focusing on the standard
setting process for ozone. Among these tasks are a review of current literature, complex
mapping analyses, elaborate field and laboratory studies (i.e., exposure response, exposure
dynamics, mechanisms of action), development and validation of process-level models of
whole-tree growth and development, and interim and final risk assessments. The
Subcommittee Is concerned that the program is too comprehensive and optimistic in scope.
The Subcommittee suggests that the 5-year time plan be revisited, taking into account
those tasks and objectives that are most likely to (1) impact the standard setting process,
(2) develop interest within the Agency for a longer-term commitment, and (3) benefit from the
lessons learned from the 10 year NAPAP experience and the 1990 Clean Air Act amendment
process. This reassessment will focus attention on the prioritization of tasks and help clarify
the level of effort to be invested in specific program components.
7.0 POLICY AND TASKS
Four basic "policy questions" presented at the beginning of the plan set the direction and
goals for research. These questions should be revised to relate them directly to specific
strategies for addressing ozone, forest resources, and the air quality standard setting
process. If the framing of the policy questions is consistent with the work plan, it will focus
the research and increase its relevance. The questions might be restated as follows:
1. Are current levels of ozone in forested areas high enough to reduce rates
of growth and/or increase rates of mortality of tree species?
2. Is the current NAAQS for ozone appropriate to prevent adverse changes
in rates of growth and/or rates of mortality of trees in forested regions
of the United States?
3. What incremental changes in rates of growth and/or rates of mortality
of tree species indigenous to different regions of the country would
be produced by 10, 25, 50% changes in ambient ozone from current
levels?
8.0 REGIONAL ASSESSMENT OF RESPONSES
The Subcommittee endorses the plan's focus on regional forest types as a means of
screening forest tree species for their sensitivity to ozone (Task 2). This endorsement is
based on a variety of biologic, climatic, and edaphic factors that are region-specific and
influence a plant's responsiveness to ozone. Of notable concern are a region's unique
combination of temporal patterns in ozone concentrations (i.e., diurnal, seasonal), tree
species composition, intra-species variability, climate, and availability of soil nutrients and
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water. Subsequently, reg,on-specific outputs can be aggregated to address national policies
on ozone and forests. The plan is less specific with respect to how it wi« address such
issues as commercial forests, national and state forests, and woody plants in urban and
horticultural environments, although such analyses are traditionally a component of the risk
assessment. The issue of urban vegetation was discussed specifically with respect to the
plan. However, it is recognized that the majority of species in urban forests are indigenous
and will be factored into the research program through Tasks 1 and 2.
9.0 INTERIM REPORT ON PROTECTION PROVIDED BY EXISTING STAN-
DARDS
Much of the current plan is directed to a long-term assessment of forest response to
current and alternative ozone levels. In the interim, the secondary NMQS will be based
principally on the responsiveness of agricultural resources as studied over the precedina 5
to 10 years. It would be beneficial for the Interim assessment of the program to provide
.nformaton, qualitatively or quantitatively, to compare the relative responsiveness of trees and
agnculturaJ spec.es. Currently, this comparison is highly imprecise because of limited data
sets, differences in physiological and ecological properties of the life forms, and often times
disparate ozone exposures between forests and agricultural landscapes. Addressing this
ISN-f T PI°V5e 9uidance to analvses of tne existing crop-based NAAQS with respect to its
abtlrty to afford protection to forest resources. Specifically, this guidance would be offered -
as probability analyses focusing on whether net impacts might occur that would have
substantive adverse effects on commercial, recreational or ecosystem values.
10. SUMMARY AND CONCLUSIONS
^e objective of this review and the resultant report is to assure that the draft research
plan, Effects of Tropospheric Ozone on Forest Trees," meets the needs of the EPA standard
setting process.
The plan addresses a highly relevant and challenging issue-welfare effects-and its
formulation recognizes that welfare effects will play a greater role in developing ambient air
quality standards for ozone than has heretofore been the case.1 The scope of the research
proposed is consistent with the need to address this issue.
The Subcommittee specifically endorses several attributes of the research plan
Foremost of these attributes Is the manner in which the plan deals with the needs of the
standard setting process, interactively with a mechanistic understanding of tree responses
to ozone. The planned objective to develop parallel modeling and experimental tasks to
«* erf **. •«•"** NAAQS. n-dn.
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scale site-specific and time-specific data to more regional* and national-level concerns of
ozone effects on forest resources is of equal importance.
The Subcommittee recommends that several aspects of the plan be revisited and
these are detailed in the body of the report. Most notably, we recommend that the plan
.nc ude an expanded role for risk assessment, greater specificity in addressing regtonafeation
of the results, and a more realistic time frame for meeting the specific objectives.
*K *'" summary'and n°t withstanding the suggestions above, the Subcommittee endorses
the draft plan as one which will provide scientifically sound data to support the standard
setting process.
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