Newsletter

Volume 7, Number 4
July - August 1990

Director’s Note

Thirty-six students and scientists from numerous
states, from Puerto Rico, from Chile and from the
People’s Republic of China are doing independent
research and assisting IBS ecologists with
research projects this summer. In addition, a
number of local individuals have been hired by
IBS administrators, horticulturists and grounds
crew to help with the day-to-day operation of the
Institute during this fast paced — and fast
growing — summer season.

Nine students selected to participate in the
Research Experiences for Undergraduates
Program are working on their own research
projects under the guidance of IBS mentor
scientists. The second John S. Eaton Fellow is
collecting and analyzing data during rainstorms,
as part of her Ph.D. research. A biology professor
who has played a major role in establishing
modern ecological science in Chile is collaborat-
ing with our ecologists. High school and college
students are gaining experience and furthering
their education by working as summer assistants
in our laboratories and administrative offices, in
the perennial garden and greenhouse. Some of the
work being done by these individuals will be
discussed in this issue, and in the September-
October issue of the IBS Newsletter.

The IBS Newsletter is published by the
Institute of Ecosystem Studies at the
Mary Flagler Cary Arboretum. Located in
Millbrook, New York, the Institute is a
division of The New York Botanical Garden.
All newsletter correspondence should be
addressed to the Editor.

Gene E. Likens, Director
Joseph S. Warner, Administrator
Alan R. Berkowitz, Head of Education

Editor: Jill Cadwallader
Printing: Central Press

INSTITUTE OF ECOSYSTEM STUDIES
The New York Botanical Garden
Mary Flagler Cary Arboretum
Box AB

Millbrook, NY 12545
(914)677-5343

REU Program: Third Year for
NSF-Supported Student Research at lES

High on the list of priorities at the Institute
of Ecosystem Studies is education. For this
reason, the Institute has developed a cur-
riculum for elementary school ecology
education, has greatly expanded its
Continuing Education Program, and has
developed ways in which college students
can work with lES ecologists to learn tech-
niques of scientific research while at the
same time making real contributions to the
body of scientific knowledge.

For three years the Institute has had help
with the latter from the National Science
Foundation (NSF) by means of its
Research Experiences for Undergraduates
(REU) Program. One goal of the National
Science Foundation is to stimulate and
support interest in the sciences, and an
effective way to achieve this goal is to
provide opportunities for college students
to participate in research. This year, out
of just over 100 applications for support
in the field of biological and behavioral
sciences, thirty-four awards were made.

The Institute received one of these grants:
funding to make it possible for nine under-
graduate students to do three months of
research with the guidance of an lES
mentor scientist.

To give the REU students as broad an
exposure to science as possible, the
Institute schedules “Research Strategies”
lectures to discuss methods for doing
research, interpreting results and commun-
icating findings; and “Research in Context”
seminars to bring ecology into the public
arena. At the lES “Forum on Opportunities
in Ecology,” students met with profession-
als who use their ecological background
in a range of research and non-research
careers. Finally, on August 20, the students
are presenting their findings to the lES
community and to the public. (Call
677-5358 for information on this sympo-
sium.) The students’ papers describing
1 990 research and results will be compiled
as an lES Occasional Publication.

Summaries of the work by three of the
REU students follow.

ELIZABETH E. CRONE, College of
William and Mary, Williamsburg, Virginia.
Mentor: Dr. Clive G. Jones.

Photosynthesis, a chemical reaction that
requires sunlight to convert atmospheric
carbon dioxide to carbohydrates, occurs in
plants’ leaves. Phenol-glycosides are
defensive chemicals found in some plants.
These chemical compounds, which protect
the plants from pathogens and pests, are

built from carbon fixed by the leaves
during photosynthesis. Shade reduces
photosynthesis, and this “stress” may then
result in less carbon being available to
make phenol-glycosides. Ms. Crone is
studying how shade alters the chemistry of
cottonwood tree leaves; her hypothesis is
that the leaves grown under shaded con-
ditions will taste better to some insect pests
due to the reduced phenol-glycoside con-
centrations. Her results have implications
to Dr. Jones’ ongoing studies of the effects
of air pollution (e.g., ozone) on plant
resistance to pests, since high levels of
ozone reduce photosynthesis, decrease
phenol-glycosides and result in increased
feeding by some insects.

Using feeding preference of the introduced
willow leaf beetle as an indicator of
phenol-glycoside levels, Ms. Crone is
comparing the palatability of leaves from
young cottonwood trees that have been
grown at high-light versus low-light
levels. Leaf disks from experimental
plants and control plants will be put in
small plastic “arenas” with beetles
collected from local willow trees, and
preferences will be determined by measur-
ing the consumption rates.

MICHELE E. PINCKNEY, Johnson C.
Smith College, Charlotte, N.C.

Mentor: Dr. Clive G. Jones.

continued on page 2

In the Greenhouse, Dr. Jones meets with
Michele Pinckney about her cottonwood study.

Rainstorm Field Work for Eaton Fellow

What invisible changes occur in the East
Branch of Wappinger Creek — the stream
that flows through the Arboretum —
during a rainstorm? Do different types of
rainstorms bring different changes? Xiaoy-
ing Ma immerses herself — literally — in
the creek during summer downpours to try
to learn the answers to these questions.

Xiaoying Ma is enrolled in a Ph.D. pro-
gram in environmental science and water
quality at the State University of New York
(SUNY) College of Environmental Science
and Forestry (ESF) in Syracuse. She hopes
to earn her doctorate by the latter part of
1992. She will return, then, to Beijing
Normal University in the People’s
Republic of China where she received her
bachelor’s and master’s degrees and where
a position in water quality assessment
awaits her.

Ms. Ma’s research and educational goals
are to become familiar with the most
modem types of analytical equipment for
studying water chemistry and to learn
current techniques for water quality model-
ing. How is water quality modeling used?
She explains: Suppose farmers living 100
kilometers downstream from a city want to
irrigate their crops with river water. The
city is a “point source” for pollution, so
environmental managers need to determine
what the water quality will be at the irriga-
tion site. Knowing the flow rate of the river
and the amount of sewage released at the
point source, they can apply existing math-
ematical models to estimate the pollutant
levels at the site in question. Ms. Ma’s

Ph.D. dissertation will concern the applica-
tion of water quality modeling to China.

Ms. Ma, recipient of the second John S.
Eaton Fellowship in Laboratory Sciences,
began three months of lES research early
in May. (The work of Alexandra Shultz,
the first Eaton Fellow, was described in the
May-June 1990 issue of the lES NEWS-
LETTER.) Ms. Ma’s goals here are to study
the relationship between water quality and
rainfall — what is the impact of storm
events on the East Branch of Wappinger
Creek? — and to gain practical experience
as she uses analytical equipment in the
Institute’s chemistry laboratories.

Her field work is done at the stream moni-
toring station near the Fem Glen. (At this
station, temperature and water level are
measured continuously for lES long-term
studies.) Hourly during each rainstorm,
until the water level reaches its peak, Ms.
Ma pulls on hip boots and wades in. At
three sites in the stream she measures
dissolved oxygen levels and takes water
level and velocity measurements, then
scoops up 250 milliliters (9 ounces) of
streamwater for chemical analysis. Back
at the lES laboratories she measures the
amount of particulate matter, determines
the pH (the degree of acidity /alkalinity of
the water) and analyzes the samples for
chemicals, including nitrate, sulfate,
calcium and phosphorus. Once the level
of the creek starts to drop, it can take
several days for it to reach its “normal”
height. During this time, the chemistry of
the streamwater changes slowly, and repre-

REU Program ,from page 1

Ms. Pinckney is also using imported
willow leaf beetles in her study, and is
focusing on the insects’ reactions to cotton-
wood tree leaves that have been exposed to
ambient doses of ozone . . . concentrations
such as those that may be found in the
Hudson Valley on hot summer days.
Willow leaf beetles will normally use
cottonwood leaves both as a surface for
egg-laying and as a food source, as
indicated above. Studies have shown,
however, that the beetles are less inclined
to lay their eggs on, and more inclined to
feed on, cottonwood leaves that have been
exposed to ozone. Ms. Pinckney will be
investigating the possible chemical
mechanisms responsible for these changes.

Her first experiment tests the hypothesis
that the decrease in oviposition, or egg-
laying, is due to a volatile chemical in
cottonwood leaves that acts as a repellent
and is released when the plants have been
exposed to ozone. Her second experiment

will see how changes in phenol-glycoside
concentrations influence the feeding
preferences of beetles. As described in the
summary of Elizabeth Crone’s study,
ozone reduces phenol-glycoside concentra-
tions and increases beetle feeding. Ms.
Pinckney plans to examine the relationship
between phenol-glycoside levels and
feeding by painting different concentra-
tions of these chemicals onto leaves.

MAYRA TORO, Interamerican University
of Puerto Rico, San German, Puerto Rico.
Mentors: Drs. Margaret M. Carreiro and
Steward T. A. Pickett.

It is commonly known that fallen leaves
are the home of microorganisms that
decay organic matter. It is not so common-
ly known that these microorganisms —
bacteria and microscopic fungi
(filamentous fungi and yeast) — also live
on healthy leaves that are still on the tree.
There is some evidence to suggest that.

Xaioying Ma, hip boots on, collects data in the
East Branch of Wappinger Creek.

sentative samples can be taken at longer
intervals.

Preliminary results show that while the
concentration of some chemicals in stream-
water decreases as the flow increases, that
of others — such as phosphorus that is
washed into the creek from surrounding
soils — increases. Ms. Ma will complete
the laboratory analyses before she leaves
lES and will present her results in
September at the qualifying examination
required of Ph.D. students at SUNY-ESF.

A copy of her findings will be available at
the Institute.

there, they may help the host plants to
fight disease.

Because fungi are sensitive to environ-
mental factors such as temperature, humid-
ity and air pollutants, Ms. Toro’s scientific
hypothesis is that fungal development will
be lower in urban areas than in rural areas.
Her focus is on yeast and filamentous
fungi, and her REU study deals with these
organisms on leaves taken from red oak
trees in three environments: The New York
Botanical Garden (urban area), West-
chester County, N.Y. (suburban area),
and Litchfield County, Conn, (rural area).
Using agar as a growth medium, she is
culturing microfungi from small disks cut
out of each leaf, and when colonies grow
she will separate each different species
onto fresh agar. Once the organisms have
been isolated, she will determine their
diversity and their frequency and in this
way learn if there is any kind of pattern
within and between the three areas.

Phosphorus . . . Sulfate . . . Acid Rain:
Dr. Caraco Investigates Possible Link

Phosphorus is required for plant and animal
life due to its roles in the storage and
supply of energy in the cell and as a com-
ponent of DNA, the genetic material of all
cells. A major source of naturally-occur-
ring phosphorus is rocks, and through their
weathering the mineral is freed into soil or
aquatic ecosystems where it is absorbed by
green plants. In this way phosphorus enters
the food web as a vital nutrient.

When freshwater ecosystems receive ex-
ceptionally high inputs of phosphorus,
algae — simple aquatic plants — take ad-
vantage of the additional nutrients and
multiply rapidly. This rapid increase can
disturb the balance of the system and result
in a process called eutrophication. Dense
and unsightly algal blooms develop; these
may, at times, be toxic to animals. When
the algae die, sink to the bottom and decay,
their decomposition consumes oxygen. The
decomposition of large amounts of this
plant material can lead to complete oxygen
depletion in bottom waters and sometimes
in the entire water column, making the
once healthy ecosystem uninhabitable for
fish and other organisms.

For four years, IBS biogeochemist Dr. Nina
Caraco has been analyzing the phosphorus
budget of Mirror Lake, near the Hubbard
Brook Experimental Forest in New
Hampshire’s White Mountains, in research
supported by grants from the National
Science Foundation (NSF) and the Andrew
Mellon Foundation. She was interested in

Dr. Caraco uses her canoe to sample lakes for
phosphorus and sulfate.

finding out what happens to the phosphorus
in algae after the plants die and sink to the
bottom sediments. In many lakes, most of
the phosphorus stays in the sediments. In
other lakes, however, the sediments act as a
continuous source of phosphorus to the
water above, and previous research has
suggested that this is most apt to happen

when the lake’s bottom waters are anoxic
— having very low levels of oxygen.

Mirror Lake has anoxic bottom waters and
should therefore have a high level of
phosphorus release, with gradual eutrophi-
cation a possible consequence. Surpris-
ingly, however, the lake has a very low
level of phosphorus release, and Dr. Caraco
wanted to discover why.

Dr. Caraco’ s investigations of this question
led her to discover that concentrations of
sulfate — a form of sulfur — were major
determinants of whether or not phosphorus
was released from sediments: high levels of
sulfate led to high levels of phosphorus
release, and those lakes with a low sulfate
content — like Mirror Lake — did not
release phosphorus. This suggested a link
to acid rain. Sulfur dioxide gas discharged
from smokestacks is one of the two major
contributors to acid precipitation. Thus,
when acid precipitation leads to acidifica-
tion of a lake, it also adds sulfur. While the
acidifying effect of acid rain has received a
great deal of study. Dr. Caraco’ s work
suggests that the sulfate pollution has its
own, previously unexpected effect: an
increase in phosphorus release from lake
sediments, with eutrophication a possible
result. This means that even so-called
“insensitive lakes” — those in which the
acid from acid rain is largely neutralized by
naturally occurring buffers — are sensitive
to excess sulfur deposition.

continued on page 4

Dr. Likens Receives Awards

Dr. Gene E. Likens was awarded an honorary degree at the Miami
University commencement exercises. L. to r.: Graduate Dean Leonard
Simutis, Dr. Likens and President Paul G. Pearson.

Twice during the past several months.
Institute of Ecosystem Studies Director
Dr. Gene E. Likens has been honored
for his pioneering research and for his
contributions to society.

At the 15 1st annual commencement at
Miami University (Oxford, Ohio),

Dr. Likens was awarded an honorary
doctor of science degree. In conferring the
degree. University President Dr. Paul G.
Pearson cited Dr. Likens’ prolific and
innovative research, his role as counsel on
ecological issues to the nation’s leaders,
and his work as an educator and advocate
of strong science programs for American
youth. Dr. Pearson also said that Dr. Likens
teaches “with a voice that reaches us all,”
and earlier during the ceremonies
Dr. Likens had done just that. As com-
mencement speaker, he urged graduates
to become environmental activists as “un-
salaried staff members of the Environ-

mental Protection
Agency, getting
involved where we live,
joining local planning
boards, zoning boards,
conservation commis-
sions, being informed,
running for office,
speaking out, writing
letters to legislators,
opposing needless
destruction of natural
resources and
minimizing waste.”

Dr. Likens is also the
recipient of the 1990 AIBS Distinguished
Service Award. In making this award, the
American Institute of Biological Sciences
(AIBS), a national organization supporting
research and education in all the biological
sciences and the application of these
disciplines to human welfare, cited

Dr. Likens’ dedication to seeking solutions
to complex environmental problems. In the
July/ August 1990 issue of BioScience, the
AIBS journal, the award announcement
described Dr. Likens’ achievement:

continued on page 4

Caraco, from page 3

Dr. Caraco, Dr. Likens and lES aquatic
microbiologist Dr. Jonathan Cole have
recently received a new NSF grant to in-
vestigate the sulfate/phosphorus-release
theory in lakes in other parts of the country
and to try to discover what it is about
sulfate that affects release of phosphorus.
This summer, sampling will be done in
lakes of New York’s Catskill Mountains,
New Hampshire, Connecticut, Pennsylva-
nia, Florida, Wisconsin and the upper
peninsula of Michigan.

In February 1990 Dr. Nina Caraco was
promoted to research associate at the
Institute of Ecosystem Studies. She began
her research at lES in February 1986 as a
postdoctoral associate, after receiving a
Ph.D. in marine ecology and biology from
Boston University.

Likens, from page 3

(He) has been a proponent of long-term
ecological research as a way to solve
global ecological problems. Using long-
term studies, he was the first to document
the impact of acid rain on terrestrial sys-
tems in the United States. He has also
looked at ways deforestation affects water
quality and flow rate .... His expertise has
been tapped by governments and private
organizations around the world.

The 1990 AIBS Distinguished Service
Award is being presented to Dr. Likens on
August 5 during the AIBS annual meeting
in Richmond, Virginia.

Summer/Fall Calendar

CONTINUING EDUCATION PROGRAM
The fall semester begins on September 1 6, with
certificate classes, short-courses, workshops,
ecological excursions and holiday decoration
workshops being offered through mid-December.
If you are not on our mailing list, please call to
request a catalogue, or pick up a copy at the
Gifford House.

SUNDAY ECOLOGY PROGRAMS

Free public programs are held on the first and
third Sunday of each month, except over holiday
weekends. Programs begin at 2 p.m. at the Gifford
House on Route 44A unless otherwise noted. For
walks, dress according to the weather, with long
pants, socks and sturdy footwear.

Call (914) 677-5359 to confirm the day’s topic.

August 19: The lES Air Pollution Garden, a
demonstration led by lES educator Melissa Hayes
September 1 6: Call the number below to learn if a
program has been scheduled for this date.

October 21 : Getting to Know Native Plants for
Naturalistic Landscaping, a walk led by
Dr. Mark McDonnell

In case of inclement weather, call (914) 677-5358
after I p.m. to learn the status of the day’s
program.

lES SEMINARS

The Institute’s program of scientific seminars
features presentations by visiting scientists or
Institute staff. All seminars are held in the Plant
Science Building on Fridays at 3:30 p.m. Free.

Sept. 14: Title to be announced.

Speaker: Dr. Barry Hart, Chisholm Institute of
Technology, Australia.

Sept. 2 1 : The Intersection Between Ecology and
Evolution, by Dr. Niles Eldredge, American
Museum of Natural History.

Sept. 28: Direct and Indirect Influences of
Subterranean Mammalian Herbivores on
Overlying Plants and Plant Communities,
by Dr. O.J. Reichman, Ecology Program Director,
National Science Foundation.

Oct. 5: Topic: Vegetational History of the
Adirondacks, by Dr. Stephen T. Jackson, Brown
University and Northern Arizona University
Oct. 12: Title to be announced.

Speaker: Dr. Leonard Smock, Virginia
Commonwealth Univ.

Oct. 1 9: Spatial Scaling and Nitrogen Sources
and Sinks in Stream Ecosystems.

Speaker: Dr. Nancy Grimm, Arizona State Univ.
Oct. 26: Topic: Snowshoe Hare Population
Cycles, by Dr. Charles J. Krebs, Univ. of
British Columbia

GREENHOUSE

The lES greenhouse is a year-round tropical plant
paradise as well as a site for controlled environ-
mental research. There is no admission fee, but
visitors should first stop at the Gifford House for
a free permit.

GIFT SHOP

Senior Citizens Days: On Wednesdays senior
citizens receive a 10% discount on all purchases
(except sale items).

Fall bulbs will be available after Labor Day.

ARBORETUM HOURS
(Summer Hours: May 1 - September 30;
closed on public holidays)

The Arboretum grounds are open Monday through
Saturday, 9 a.m. to 6 p.m.; Sunday 1 - 6 p.m.

The Greenhouse and the Plant Science Building
close at 4 p.m.

The Gift and Plant Shop is open Tuesday through
Saturday 1 1 a.m. to 5 p.m. and Sunday 1 - 5 p.m.
(closed weekdays from 1 - 1:30 p.m.).

Note: Winter hours begin October 1. Please call
the number below for information.

All visitors must obtain a free permit at the Gifford
House for access to the Arboretum. Permits are
available up to one hour before closing time.

For more information, call (914) 677-5359 weekdays from 8:30 - 4:30.

INSTITUTE OF
ECOSYSTEM STUDIES
The New York Botanical Garden
Mary Flagler Cary Arboretum
Box AB, Millbrook, New York 12545

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Volume 7, Number 4
July - August 1990

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