Newsletter

Volume 13, Number 1
January - February 1996

Director’s Note

Global climate change is potentially one of
the most serious environmental problems
that human societies have ever had to face.
Global climate change results from an
increased concentration of so-called
greenhouse gases in the atmosphere. Carbon
dioxide, one of the major greenhouse gases,
has been increasing in concentration since
the mid-1950s, primarily due to the
combustion of fossil fuels and to worldwide
deforestation.

Global warming is one of the better-known
consequences of higher concentrations of
greenhouse gases. But a build-up of carbon
dioxide in the atmosphere could have other
environmental impacts as well. Plants —
upon which most organisms depend for food
— take up carbon dioxide during photosyn-
thesis. Could they be affected by increased
concentrations of this gas? As a Guggenheim
Fellow, lES chemical ecologist Dr. Clive
Jones investigated this question, studying the
effects of environmental change on the food
quality of plants. His findings are summa-
rized in the cover story.

The lES Newsletter is published by the
Institute of Ecosystem Studies, located at
the Mary Flagler Cary Arboretum in
Millbrook, New York.

Director; Gene E. Likens
Administrator; Joseph S. Warner
Head of Education; Alan R. Berkowitz
Newsletter editor; Jill Cadwallader

Address newsletter correspondence to the
editor at;

Institute of Ecosystem Studies
Education Program, Box R
Millbrook NY 12545-0178

or e-mail to Jillcad@aol.com

Printing; Central Press, Millbrook, N.Y.

Does Environmental Change Affect the
Food Quality of Plants?

Natural ecosystems are very complex, so
some ecologists use models that capture the
essence of ecosystem complexity but can
be controlled and replicated. The recently
developed Ecotron facility, at the Centre for
Population Biology at Imperial College at
Silwood Park in Britain, is providing such
models. The Ecotron’s chambers, housing
many identical, relatively simple, but fiilly
functioning ecosystems, make the facility a
potentially invaluable tool for increasing
our understanding of real ecosystems.

lES researcher Dr. Clive Jones, recognizing
the Ecotron’s value as a unique research
tool, has been virtually commuting to the
British facility. His goal: to study the
effects of global environmental change on
food quality.

good quality food to these organisms when
it is high in nitrogen and low in defensive
chemicals and lignin (a tough, rigid
polymer that adds support and strength to a
plant but is not easily digested or decom-
posed by other organisms). Conversely,
plant material that is low in nitrogen but
high in defensive chemicals and lignin is
poor quality food.

“What we don’t know is whether or not
plant food quality is going to be better or
worse as the global environment changes.”
It is important to know this because,
directly or indirectly, most of the other
organisms on the planet, including humans,
depend on plants for food.

The Ecotron Ecosystems

In 1994 Dr. Jones (below) received a
prestigious Guggenheim Fellowship, which
he used over the following year to relate
global environmental change — particu-
larly increases in atmospheric carbon
dioxide — to the food quality of plants for
other organisms. “Plant-eating animals,
such as insects, and microorganisms such
as plant pathogens and the microbes that
decompose dead plants and recycle
nutrients, are very much affected by the
chemistry of living and dead plants,” Dr.
Jones explains. “Plant material tends to be

The Ecotron facility, which began opera-
tion in 1991, is headed by Professor John
Lawton (who is also an adjunct scientist at
lES). At present the project is funded
largely by England’s National Environmen-
tal Research Council.

The Ecotron consists of 16 chambers, each
3 meters (10 feet) on a side, in which such
variables as day length, atmospheric
composition, temperature, and rainfall can
be precisely controlled. Each chamber
contains a simple natural ecosystem: soil,
complete with resident earth-
worms, collembola (small mite-
like animals that chew on leaf
litter, fungi, etc.), woodlice, fimgi
and bacteria; a variety of plant
species and the insects and snails
that eat them; and insects that eat
the insects that eat the plants. (To
allow for experiments that include
multiple generations of plants over
a short time, the researchers have
used a plant community of four
weedy, fast-growing plant species:
hairy buttercress, a mustard; an
annual grass; and spurrey and
tansy ragwort, two other common
plants of waste ground.) These are
fully functioning ecosystems,
having much of the complexity of
the real world yet affording the
control and replication generally
associated with experiments using
single plants in pots.

The Ecotron research team is
looking at how each model
ecosystem behaves, from overall
carbon and nitrogen budgets to

continued on following page

Food Quality, from page 1

What Determines the Amounts of Phenolics in a Plant?

individual organisms. So multifaceted and
wide-ranging is this work that it requires
close collaboration among several dozen
scientists.

Changes in Food Quality
in the Ecotron

Dr. Jones and colleagues on the Ecotron
research team found that increased atmo-
spheric carbon dioxide concentrations
appear to decrease food quality by increas-
ing the amounts of phenolic defensive
compounds, chemicals that are also the
precursors of lignin. These compounds
increased in concentration in all four of the
plant species in the ecosystem — but only
once the soil nutrients were depleted (see
box).

Because this carbon dioxide-induced
increase in phenolics depends on soil
nitrogen conditions, it does not show up at
all in the first generation of plants but
becomes a major effect by the second and
third generation. This is because, as the
plants grow, the availability of soil nitrogen
declines. The fact that four quite different
plant species respond similarly suggests
that the underlying biochemical controls on
phenolic production may be the same in
many plant species.

Most importantly, the findings suggest that
the effects of elevated carbon dioxide on
food quality will depend on the nitrogen
status of the soil. So, in ecosystems with
high soil nitrogen, elevated carbon dioxide
would be expected to have little effect on
food quality, while in ecosystems with low
soil nitrogen, elevated carbon dioxide
would be expected to decrease food quality.

Dr. Jones anticipates additional Ecotron
studies will show whether or not the
changes in plant chemistry the collaborators
have seen will in turn affect the abundance
of the insects and other animals feeding on
these plants and the rate at which the dead
plant material decomposes.

While he cannot be sure that the effects
seen in the Ecotron ecosystems will occur
in the more complex ecosystems in nature.
Dr. Jones notes that the Ecotron experi-
ments have revealed a new, complex
interaction between elevated carbon
dioxide and soil nitrogen that was not
previously recognized. It now should be
possible to test these findings elsewhere
and see if indeed the controlled and
replicated Ecotron ecosystems are a
valuable tool in unraveling nature’s
complexity.

All higher plants contain phenolics. These
chemicals play key roles in determining
food quality to other organisms. For
example, lignin — the organic compound,
tough to digest and decompose, that makes
wood woody — is made entirely of
phenolics.

Current thinking about phenolics predicts
that more should be made when more
carbon is taken up by plants. As photosyn-
thesis — plants’ carbon-fixing process —
increases with increased atmospheric
carbon dioxide, phenolics should increase.
But this explanation does not fit with the
results found in the Ecotron: the amount of
plant phenolics produced under elevated
carbon dioxide as compared to ambient
carbon dioxide actually was controlled by
the amount of soil nitrogen.

To explain these results, Dr. Clive Jones
and his colleague Dr. Susan Hartley of the
Institute of Terrestrial Ecology, Banchory,
Scotland, have developed a new model of
control over phenolic production in plants.

Drs. Hartley and Jones start with the
knowledge that the production in the plant
of both phenolics and the proteins used in
growth and photosynthesis requires the
same chemical compound — the amino
acid phenylalanine. The two pathways
“compete” for this amino acid. The
scientists’ hypothesis is that when soil
nitrogen — a nutrient — is readily
available, plants tend to make a lot of
protein for growth and very little phenyla-
lanine goes to phenolics. When plants are
grown under increased levels of atmo-
spheric carbon dioxide they need less
protein for photosynthesis, but the savings
in phenylalanine still go to protein for
growth and not to phenolics.

However, when nitrogen in the soil is
limited, protein synthesis for plant growth
slows down. When plants grow at low
levels of nitrogen and high levels of
carbon dioxide, the protein savings from
increased efficiency of photosynthesis
frees up phenylalanine, which then is used
to make phenolics.

lES Graduate Student Wins Robert Whittaker Award

Bacteria are the most diverse and abundant
organisms on Earth. They are specialists,
with species growing just about everywhere
and performing a myriad of functions.

Some live in snow, while others survive
near deep ocean vents v/here the water
temperature reaches 350°C (662°F). Some
thrive in or on animals and plants, others in
soils and in stream sediments. Some are
harmful — pathogenic bacteria produce
toxic substances when they enter our
bodies, often resulting in infection or
disease — while others are useful, for
example the nitrogen-fixing bacteria that
live in nodules on the roots of plants like
clover and alfalfa and convert nitrogen gas
to a form of nitrogen that plants need for
growth.

Given the vast numbers
of bacterial species that
exist, the contributions
of the majority to their
ecosystems are as yet
unknown. New knowl-
edge is being created all
the time, thanks to the
work of scientists like
lES graduate student
William Sobczak.

Knowing that microor-
ganisms influence, if not
regulate, the chemistry
of water, Sobczak is
investigating the
relationship between

bacteria in stream sediments and the
chemistry of stream water.

One of the chemicals found naturally in
stream water is organic carbon, which is an
end product of the decomposition of forest
debris, algae and other formerly-living
material. Organic carbon is a nutrient, a
requirement for bacterial growth, and at his
field sites Sobczak is studying how much
organic carbon is available to fuel the
bacteria that live in stream sediments. He is
investigating changes in water chemistry
and microbial ecology, measuring the
amount of organic carbon and its availabil-
ity to bacteria in different subsurface
habitats.

continued on following page

Adventures in Scientific Thinking

by Ann Botshon

For over a decade, the Institute of Ecosys-
tem Studies has supported curriculum
development and local school programs to
sharpen young people’s awareness of the
natural world. lES educators also recognize
the ongoing need to develop a large corps
of teachers knowledgeable about ecology
and thereby able to foster the development
of students’ scientific thinking skills.

Two new books written by lES research
and development specialist Ms. Kathleen
Hogan aim to do just that. Rita, a novel
written for young people, shows that it can
be fun and satisfying to think scientifically.
Accompanying Rita is a guidebook.
Promoting Student Thinking: A Teacher 's
Guide to Linking Science and Literature
Through Rita , that leads teachers through
each chapter in the novel with suggestions
for facilitating student discussions, writing
and projects.

Both new publications are important
supplements to Eco-Inquiry: A guide to
ecological learning experiences for the
upper elementary/middle grades, written by
Hogan and published in 1994. This earlier
publication offers a series of experiences,
applicable in schools throughout the
country, to help encourage scientific
awareness and thoughtful inquiry in
students.

“I wrote Rita to tackle the problem of
‘transfer’, the effort to prevent knowledge
and skills learned in school from becoming

inert in other contexts,” Hogan, at
right, explains. “I wanted to create
a role model who applies scientific
thinking skills and ecological
knowledge to everyday situa-
tions.” Rita is the story of a girl
who becomes fascinated with a
small marsh near her school.
Discovering that the wetland is
slated for development, she learns
more about its plants and animals
and mobilizes her friends to help
educate the community about its
value.

“A central goal of Rita is to show
what it means to think critically,
creatively, fluidly and analytically
— in other words, scientifically —
in everyday life,” says Hogan.

“This whole project is an effort to
focus students on using their minds well.”
Rita aims to impart the idea that students
can become more capable thinkers by
taking responsibility for their own learning.

The exercises in the new guidebook, keyed
to the novel, give all teachers a way to
make the best use of science material.
“Elementary teachers who have expertise in
language arts find it appealing to teach
science through literature,” Hogan explains.

The guidebook also provides suggestions
for activities in which students can apply
their skills and knowledge to investigating
environmental issues in their own commu-

nities, encouraging them to decide for
themselves what projects and values are
important. In every community there’s an
ecological issue that resonates with young
people, and that can be a gateway into other
ecological explorations.

Rita and the Teacher ’s Guide are being
published by Kendall/Hunt Publishing
Company. The project is supported in part
by the National Science Foundation and
public funds from the New York State
Council on the Arts. Both publications are
expected to be available this spring.
Ordering information will be in an upcom-
ing issue of the lES NEWSLETTER.

Award, from page 2

Mr. Sobczak’s research sites are at streams
across the Hudson River Valley, from
relatively pristine forested catchments in
the Catskill Mountains to areas where
agriculture has an impact on water quality.
One of his sites is along the East Branch of
Wappinger Creek, which meanders through
the Institute’s forests and lowlands. Not far
from where Sobczak sits in the photograph
at left is a bend in the creek where stream
water on its way downstream passes
through sediment that has built up along the
inside bank. Because microorganisms
anchor to pebbles and sand grains, this area
is microbially-rich and therefore is an
excellent habitat to investigate potential
changes in organic carbon. At shallow
wells, Sobczak pumps groundwater from
sediments at a level just below that of the
stream’s channel, then takes the samples to
the lES laboratories where he analyzes
them for bacterial communities and water
chemistry.

Findings from Sobczak’s research will
contribute to the considerable body of

knowledge that has been amassed by lES
and Cornell University ecologists about the
transport of organic matter through the
Hudson River watershed. The Hudson
River’s many tributaries have a direct effect
on the water quality of its mainstem. For
example, the transport of nutrient-rich, high
organic stream water from catchments in
agricultural regions within the Hudson
River watershed can influence greatly the
biota and chemistry of the river. Mr.
Sobczak has demonstrated that organic
matter from the tributaries he is studying
differs in its availability to bacteria and
hence in its importance to the Hudson
River’s food web and water quality.

Robert H. Whittaker Award

Dr. Robert H. Whittaker was an interna-
tionally recognized plant community and
ecosystem ecologist at Cornell University,
where he was a professor in the Section of
Ecology and Systematics. Now, each year
an award is made in his name for the best
oral presentation at the annual Cornell

University’s Section of Ecology and
Systematics’ Annual Graduate Student
Symposium. This year’s symposium,
attended by graduate students and faculty,
was held on January 18 and 19, and over 30
scientists presented papers on their current
research. Mr. Sobczak, whose paper
described the “Microbial Metabolism of
Dissolved Organic Carbon in Stream
Hyporheic Zones”, was a co-recipient of
the Whittaker Award.

Mr. William Sobczak is a graduate student
at the Institute of Ecosystem Studies and
Cornell University, doing research toward
a Ph.D. in collaboration with his lES thesis
advisor Dr. Stuart E. G. Findlay and his
Cornell thesis advisor Dr. Robert W.
Llowarth. His research was funded first by
the Hudson River Foundation and is
supported now by a National Science
Foundation grant and a graduate fellow-
ship from the Environmental Protection
Agency.

CONTINUING EDUCATION
Call the Continuing Education Program office at
914/677-9643 for information on spring
semester classes, workshops and excursions.

Early spring programs include;

Landscape Design

Apr. 20: Field Course: Contour Plans
Apr. 27: Computer Graphics in Landscape
Design

Gardening

Apr. 1 1 (6 sessions): Insect Pests and Diseases
of Plants

Apr. 13 (4 sessions); Woody Plants
Apr. 14; Water Gardens
Apr. 20: Integrated Pest Management
Apr. 20: Raised Bed Vegetable Gardening
Apr. 21 : Growing Herbs Indoors
May 4: Shade Gardening: Using the Eastern
Deciduous Forest as a Design Model
Natural Science Illustration
Apr. 27 & 28: Pen & Ink I

Workshops

Apr. 13: Bringing Out the Best in Shrubs
May 5: Planting Noah’s Garden

Other Courses

May 1 (5 sessions): Plant Pharmacy: Exploring
Plants for Health Remedies

SUNDAY ECOLOGY PROGRAMS
Free public programs are held on the first and
third Sunday of the month, except over holiday
weekends. Call 914/677-5359 to confirm the
day’s topic or, in case of poor weather, to learn
the status of the day’s program. The following
programs begin at 2 p.m. at the Gifford House:
Apr. 21 : The Spring Fever Hike, a walk led by
Michael Weintraub

May 5: A Stream Walk, led by Dr. David Strayer
May 19: Super Soil: The World Beneath Our
Feet, a walk led by Alan Lorifice

* We strongly recommend that participants wear
long pants tucked into socks and sturdy
waterproof footwear for all outdoor programs.

INSTITUTE OF
ECOSYSTEM STUDIES
Education Program
Box R

Millbrook, New York 12545-0178

Newsletter

Calendar

lES SEMINARS

Free scientific seminars are held each Friday at
3:30 p.m. at the lES Auditorium:

Apr. 12; Title to be announced. Speaker:

Dr. William Currie, The Ecosystems Center,
Woods Hole, Massachusetts
Apr. 19: The Evolution and Adaptive Signifi-
cance of the Leafmining Habit. Speaker;

Dr. Edward F. Connor, Univ. of Virginia
Apr. 26: Landscape Vegetation Modeling with
Vital Attributes and Fuzzy Systems Theory.
Speaker; Dr. David W. Roberts, Utah State Univ.
May 3: The Ecology of Fear: Consequences of
Feeding Under Predation Risk. Speaker: Dr. Joel
Brown, Univ. of Illinois - Chicago
May 10: Restoring Ecosystems for Endangered
Species: The Acid Test of Wetland Ecology.
Speaker: Dr. Joy B. Zedler, Pacific Estuarine
Research Lab, San Diego State Univ.

VOLUNTEER OPPORTUNITIES

Volunteers are needed to work with Gifford House
Visitor and Education Program staff in ecology
education for school groups, as trail monitors, and
in the lES Gift Shop. To learn the responsibilities
and benefits, call Ms. Su Marcy at 914/677-5359.

GREENHOUSE

The lES greenhouse, a year-round tropical plant
paradise and a site for controlled environmental
research, is open until 4:00 p.m. daily except
public holidays. Admission is by free permit*.

HOURS

Winter hours: October 1 - April 30
Closed on public holidays.

Roadways are closed when snow-covered.
Public attractions are open Mon. - Sat., 9 a.m. -
4 p.m. & Sun. 1 - 4 p.m., with a free permit*.

The lES Gift and Plant Shop is open Mon.- Sat.,

1 1a.m. - 4 p.m. & Sun. 1 -4 p.m. (The shop is
closed weekdays from 1 - 1:30 p.m.)

* Free permits are required for visitors and are
available at the Gift Shop daily until 3 p.m.

lES GIFT AND PLANT SHOP
New in the Shop ... hand-painted gourd bird
houses and feeders ... hand-painted rock
paperweights ... lES postcards ... lES sweatshirts
in new colors for spring ... for children ...
Peterson’s First Guides ... acid rain test kits ...
books of science fair project ideas

•• Gift Certificates are available ••

Senior Citizens Days: 10% off on Wednesdays

MEMBERSHIP

Join the Institute of Ecosystem Studies. Benefits
include a member’s rate for courses & excursions,
a 1 0% discount on Gift Shop purchases, a free
subscription to the newsletter and participation in
a reciprocal admissions program. Individual
membership: $30; family membership; $40. Call
Ms. Janice Claiborne at 914/677-5343.

The Institute’s Aldo Leopold Society
In addition to receiving the benefits listed above,
members of The Aldo Leopold Society are
invited guests at spring and fall lES science
updates. Call Ms. Jan Mittan at 914/677-5343.

TO CONTACT lES ...

... for research, graduate opportunities, library
and administration:

Institute of Ecosystem Studies
Box AB

Millbrook NY 12545-0129
Tel: 914/677-5343 • Fax: 914/677-5976
Street address: Plant Science Building,

Route 44A, Millbrook, N.Y.

... for education and general information:
Institute of Ecosystem Studies
Education Program, Box R
Millbrook NY 12545-0178
Tel: 914/677-5359 • Fax: 914/677-6455
Street address: Gifford House Visitor and
Education Center, Route 44A, Millbrook, N.Y.

lES e-mail: cacw@vm.marist.edu

lES borne page: http;//www. marist.edu/~ies

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Volume 13, Number 1
January - February 1996

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