Newsletter

Volume 15, Number 6
November - December 1998

Director’s Note

While the living components of ecosys-
tems attract the most attention, non-
living parts are just as important when we
consider the “health” of the whole. Non-
living components, including rocks, soil,
water and air, constitute the physical
environment, and from them come
inorganic chemicals that are the
nutrients required for life.

The nutrients that cycle through the
ecosystem and sustain animals, plants
and microbes include carbon, nitrogen,
phosphorus, calcium and sulfur. My own
research at the Hubbard Brook Experi-
mental Forest in New Hampshire has
demonstrated how imbalances in
biogeochemical cycles can be harmful to
the overall health of the system. This
issue of the newsletter features the work
of Dr. Louis Verchot, who has developed
a way to measure and thereby understand
some of the elusive components of the
nitrogen cycle.

The IBS Neivsletteria 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
e-mail: CadwalladerJ@ecostudies.org

Printing: Central Press, Millbrook, N.Y.

Measuring the Impact of the Invisible

You’re probably a reasonably observant
person. Maybe you even fit the profile of
the “keen observer”. But no matter how
hard you try to take in all that’s going on
around you, some things always will be
invisible. And when these invisible things
are linked to much bigger things — acid
rain and global warming to name two —
it’s important to be able to make them if
not visible at least measurable.

At the Institute of Ecosystem Studies, Dr.
Louis Verchot is blending scientific
creativity with technical ingenuity to make
this possible. Dr. Verchot is measuring a
process that produces nitrogen gases in
the environment. As you will see, this is
not so easy to do. But before we get into
that, a little background may help explain
the relevance of this work.

Invisible Elements

The nitrogen cycle is a biogeochemical
cycle that has regulated ecosystems
throughout Earth’s history. Most of the
materials contributing to biogeochemical
cycles are invisible things, chemical
elements circulating from environment to
biological organisms and back again.
You’re surrounded by the tangible
products of these cycles: the water you
drink and the oxygen you breathe, the
plants in the landscape . . . not to mention
what’s on your dinner plate, and your own
protoplasm, bones and teeth.

Bonded with other elements, nitrogen
builds proteins, vitamins, hormones,
enzymes and other compounds essential
for life. To build these life-sustaining
compounds, nitrogen gas, which makes up
nearly 80% of the Earth’s atmosphere,
must be converted into a usable form,
called nitrate. In nature, this conversion is
accomplished through the effects of
lightning, meteor trails and cosmic

radiation in the atmosphere; by certain
algae in aquatic ecosystems; and by nitro-
gen-fixing bacteria in soils and water, and
in nodules on the roots of legumes such as
peas, beans, clover and alfalfa. Industrial
processes such as the manufacture of
fertilizers also make nitrate.

Decomposition of fallen leaves, animal
wastes and dead plants and animals
returns nitrate to the system, at which
point denitrifying bacteria in soils con-vert
it back to nitrogen oxides — precursors
for acid rain, ozone production and the
greenhouse effect — as well as nitrogen
gas. Denitrification, then, is the nitrogen
cycle’s equivalent of transporting recy-
clable products from the transfer station
to the recycling center.

In a relatively recent development, human
actions in some parts of the world are
literally fertilizing forests. In the northeast-
ern United States, for example, increased
nitrogen mobilization comes from
agricultural runoff, which carries with it
nitrate from the escalating use of fertiliz-
ers, and from acid rain, of which nitric
acid is a component. Whereas up to a
point an additional input of nitrogen can
boost plant growth, nitrogen satura-tion is
a real problem — when forests can-not
absorb any more nitrogen there may be a
decline in productivity, an increase in
plant disease from pests and pathogens,
and pollution of surface water and
groundwater. There are other dangers as
well. Methemoglobinemia or blue-baby
syndrome, for example, is a condition that
results from nitrates in drinking water
being converted in the intestinal tracts of
infants to chemicals that oxidize hemoglo-
bin in the blood. When hemoglobin can
no longer transport oxygen, brain damage
or death can follow.

Measurements
Influence Policy

How do environmental
managers and policy
makers deter-mine how
much nitro-gen is safe
for an eco-system,
thereby pre-venting or
at least reducing the
negative impacts?
Frequently, they
depend on ecolo-gists
to tell them the
“critical loads”, above
i which the ecosystem
5 degrades. And
g ecologists base their
determinations on a

continued on page 3

Dr. Verchot developed the apparatus he uses to measure denitrification. Here
he holds one of the glass tubes in which soil samples are incubated.

Baltimore Ecosystem Study Going Strong at End of First Year

In October 1997, the Institute received
funding through the National Science
Foundation Long-Term Ecological
Research (LTER) program to launch the
Baltimore Ecosystem Study. This pio-
neering project, one of only two urban
LTERs in the United States, was intro-
duced to newsletter readers a year ago
(Vol. 14, No. 6), and the past issue de-
scribed some of the vegetation studies
now under way. The first annual
meeting of the Baltimore Ecosystem
Study was held early in October, at the
time of the project’s first anniversary.

One of the strengths of the Baltimore
Ecosystem Study (BES) is its extremely
collaborative nature. The recent
meeting provided the first formal
opportunity to engage BES partners —
city, county and state agencies;
teachers; neighborhood associations

and watershed associations — in dialog
with project scientists, students and staff.
Among the meeting’s accomplishments,
according to Dr. Steward Pickett, lES

ecologist and BES Project Director, were
development of a greater understanding
of the multiplicity of interests among the
group, and preparation of a list of
questions for guiding watershed research.

The meeting was also a celebration of the
completion and occupancy of new BES
laboratory and office space in the Tech-
nology Research Center Building at the
University of Maryland, Baltimore County.
Speaker at the opening reception was Dr.
Freeman Hrabowski, III, president of the
university and a strong advocate for the
Baltimore Ecosystem Study.

Dr. Hrabowski, center, luilh Ms. Jacqueline
Carrera, Executive Director of the Parks and
People Foundation and one of the BES principal
investigators, and Dr Pickett.

SEEDS for a New Generation of Ecologists

Eleven students from institutions partici-
pating in the Strategies for Ecology Edu-
cation, Development and Sustainability
(SEEDS) project attended the joint annual
meetings of the American Institute of
Biological Sciences and the Ecological
Society of America (ESA), held in Balti-
more in August. Among them were Tus-
keegee University students Mr. M. Kamau
R. Crawford and Ms. Zakiya Holmes, who
met with U.S. Secretary of the Interior
Bruce Babbitt following his ESA Plenary
Address. Mr. Crawford and Ms. Holmes
spent the summer at lES doing research
with Drs. Peter Groffman and Louis
Verchot in the Institute’s Research Experi-
ences for Undergraduates program,

SEEDS is a partnership formed in 1996
between the United Negro College Fund,
the Ecological Society of America and lES.
Its goal is to increase minority repre-

sentation in the field of ecology through
recruitment and curriculum development.
Funding for the program comes from The
Andrew W. Mellon Foundation, which
recently not only renewed funding of the
program through 2001, but also expanded
its support so that 10 institutions, com-

pared to five originally, will be able to
participate. The ESA portion of the
project is run by Dr. Alan R. Berkowitz,
lES Head of Education and ESA Vice
President for Education and Human
Resources, and by Project Coordinator
Stephanie Shoemaker, also at lES. •

Left to right: lES Visiting Scientist Dr. Richard Pouyat, ESA Gender and Minority Affairs Committee
Chairperson ( and a BES principal investigator), Mr. Crawford, Ms. Holmes and Secretary Babbitt.

Invisible, from page 1

“mass balance” approach, which is a kind
of ecosystem accounting: What enters a
system, what is stored and what leaves
should add up. Unfortunately, if the meas-
urements are inaccurate, the determina-
tions and balance also are inaccurate.

The products of denitrification are gases,
and nitrogen gases moving into an atmos-
phere that is predominantly nitrogen are
extremely difficult to measure. Existing
methods to determine how much nitrogen
is released by denitrifying bacteria in
forest soils have resulted in gross underes-

timation of nitrogen leaving the ecosys-
tem. This in turn has led to inaccuracies in
mass balance calculations and to potential
errors in determining how much nitrogen
we can tolerate in our forests without
causing damage.

As an lES post-doctoral associate. Dr.
Verchot took on the challenge of measur-
ing these nitrogen gases, produced in
parts per million but resulting in an
estimated four to five pounds released per
acre per year, and has developed and
constructed a system to measure nitrogen

flux in a nitrogen-free environment. The
apparatus consists of glass tubes, metal
piping and an incubator. Soil samples are
put in the tubes and a mixture of inert
argon gas and oxygen is piped through,
purging nitrogen from the system. The
system is then closed. Denitrifying
bacteria present in the incubating soils
convert nitrates to gases, which are
sampled at intervals and injected into an
instrument called a gas chromatograph. A
print-out records the amounts of nitrogen
gas and nitrous oxide — one of the gases
continued on page 4

Everything is Connected?

A few years ago, one of the most important
international scientific journals, Science,
listed the “top 20” scientific ideas. Most of
them were about physics, chemistry,
physiology, or genetics and evolution.

Only the last one was about ecology. As an
ecologist, I hope that merely reflects the
relative youth of ecology as a science,
rather than some real expression of the
value of our discipline. At least we made
the list.

So, what was the big idea in ecology that
made it onto that august list? “All life is
connected.” Sounds pretty good, and it is
hard to argue with as it stands. But
something is wrong with that idea as the
sole portrait of ecology in a scientific hall
of fame.

First, I must admit that there is some
validity to the idea. Ecology as a science is
about connections. Ecologists study the
connections between organisms and their
physical environments. For instance,
connections can appear as the flow of
energy in the food a predator eats, or the
physical stresses that control where a plant
can grow. Other kinds of connections
include the interactions between organ-
isms, like those behavioral interchanges
that determine territorial boundaries, or
breeding success. Interactions in ecology
also include the subtle chemical transfor-
mations by microbes of the chemicals
locked up in dead organic matter into
nutrients that other organisms can use. All
these kinds of interactions and transforma-
tions are connections.

There are other kinds of connections in
ecology as well. Organisms, information
encoded in genes, nutrients, toxins, and
the whole roster of ecologically important
things, can move from place to place.
Sometimes, these movements are obvious,
as when flocks of birds migrate south for
the winter, or smoke transports some of
the nutrients released in the process of
combustion, or plumed seeds fly away on
an autumn wind. In other cases, the
movements are subde, and knowable only
by sophisticated techniques. Examples of
such subtle connections are the movement
of invisible pollutants in apparently clear
air, or the transport of chemicals in
ground water, or the concentration of a
toxin in the fat of a voracious predator.

Yet another kind of connection in ecology
is one that occurs through time. Eor
example, the composition and physical
structure of the forests of Dutchess County
today reflect the way that farmers and

settlers used the land decades and
centuries ago. Whether land was grazed or
plowed affects its capacity to support
different kinds of trees or the rates at
which those trees can grow. Over an even
longer time, where the melting glaciers
dumped coarse versus small sediments
12,000 years ago affects the moisture
content and quality of our soils today.

So ecology is about connections. Connec-
tions are what make the world look and
work the way it does. But still, there is
something wrong with the surprisingly
naive statement, by a journal whose editors
ought to know better, that everything is
connected to everything else.

If that statement were literally true, the
world would be a fairly homogeneous
smear. Uniform and instantaneous
connection would mean that the world
would offer everywhere very similar kinds
and amounts of resources for plants and
animals. It would mean that different
places would be equally stressful or
benign, and that they would be inhabited
by the few species that would be able to
use just that range of conditions and
resources well.

This boring uniformity is clearly not the
case. Ecology is an interesting science, and
generates crucial knowledge for manage-
ment and understanding the world,
because things and places are not simply
connected — they are differentially
connected. Some of those fluxes of
material, energy and organisms are
stronger or faster than others. For
instance, the mineral forms of nitrogen
move more readily in moist soils than do
the materials carrying phosphorus.
Likewise, some places hold onto the
materials or organisms that move into
them better than others. For instance, the
edges between forests and fields are hot
spots for certain kinds of organisms.
Differential connection also influences
interactions through time. The echoes of
different past events fade at different
rates, so that the effects of even a very
large snowstorm on forest tree popula-
tions may disappear over a few years, while
the legacy of chemical pollution may take
decades to centuries to fade to levels
similar to those before the spill or
dumping.

So the useful idea about ecological
connection is not that connection is
everywhere. The pervasiveness of connec-
tion is, in a sense, just a definition of
ecology. Ecology can be defined as the

by Steward T.A. Pickett

science of the patterns and causes of
connections — that is, interactions, fluxes,
dynamics, and transformations — that the
living world exhibits. Taken at that level of
generality, ecology does of course suggest
that an interaction or event at one place
and a specific time may well have effects
that appear elsewhere or at a later time. It
is valuable to recognize this kind of
“connectedness” in the world when we
take individual, economic, or social
actions. But expecting that everything
literally affects everything else cheapens
ecology, because, in fact, many events or
processes have very little or virtually no
effect on much of anything else. So the
idea of connection doesn’t mean that
every event or process will strongly,
directly, or immediately affect every other
place and thing.

What is true about connections in the
natural world is that they are often subtle,
indirect, or slow. They often act over long
distances, or their effects may take a long
time to appear. This is what is interesting
and challenging about ecology. It is the
science that discovers how — how fast,
how long, how distant — different
connections occur. It is the science of
ferreting out the unsuspected connections
and the indirect links. Just because some
connections are subtle doesn’t mean they
are trivial. Recall that the importance of
DDT as a pollutant was missed because it
doesn’t have direct effects at the concen-
trations it typically reaches in a contami-
nated environment, but only after it has
been concentrated in the fat of long-lived
animals, or those that forage widely for
their animal prey.

The metaphor that the journal Science
assigned to represent ecology is quite
misleading. Ecology isn’t important
because everything is connected to
everything else. It is important because it
discovers how things are connected, and
exposes not only the strong and obvious
connections, but also the hidden, slow, or
distant ones as well. Different kinds and
strengths of connections drive and shape
the natural world, but not every connec- #
tion equally.

Dr. Steward Pickett is a senior scientist at the
Institute of Ecosystem Studies. In a follow-up
article in the next issue of the newsletter, Dr.
Pickett propose s an idea that might better
represent the discipline of ecology in that “top
20” list.

INSTITUTE OF
ECOSYSTEM STUDIES
Education Program
Box R

Millbrook, New York 12545-0178

Newsletter

Volume 15, Number 6
November - December 1998

Invisible, from page 3

responsible for air pollution — released.
Using this apparatus in the lES laboratory,
Dr. Verchot will be measuring denitrifica-
tion in soils from forests around the
Institute, at the Hubbard Brook Experi-
mental Forest in New Hampshire and Bear
Brook in Maine, and from sites in the
Catskill Mountains, Massachusetts and
Virginia.

Results from Dr. Verchot’s research should
help to bring the mass balance of nitrogen
closer to reconciliation. Then, armed with
more accurate data, ecologists will be
better able to inform decision makers
about safe amounts of nitrogen deposition
to forest ecosystems. •

Dr. Louis V. Verchot is an ecosystem ecologist
with a doctoral degree in forest soil ecology from
North Carolina State University. Prior to his
arrival at the Institute in October 1 997, Dr.
Verchot had been a postdoctoral associate at the
Woods Hole Research Center. During this
period, he worked in Brazil, just south of the
mouth of the Amazon River, studying the flux of
greenhouse gases — carbon dioxide, methane,
nitrous oxide and nitric oxide — from the soil to
the atmosphere. His findings now are being
used by scientists at NASA to estimate green-
house gas emissions from soils in Amazonia.

This work also is providing important
information to the Brazilian government in its
efforts to account for greenhouse gases emis-
sions, as required by the Framework Convention
on Climate Change. Dr. Verchot plans to
continue his research in the Amazon, applying
what he is learning at lES to further study of
greenhouse gases. At lES, Dr. Verchot is
collaborating with microbial ecologist Dr. Peter
Groffman, as well as with Drs. Gary Lovett and
Kathleen Weathers.

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CONTINUING EDUCATION
For a winter-spring catalogue and program
information, call the Continuing Education office
at 914/677-9643.

lES SEMINARS

Free scientific seminars are held each Friday at
1 1:00 a.m. at the lES Auditorium. A schedule for
the winter-spring series, which begins January 15,
was not available at press time. Call 914/677-5343
to request a copy, or find it on the lES Website
(www.ecostudies.org) after January 8.

GREENHOUSE

The lES greenhouse, a year-round tropical plant
paradise and a site for controlled environmental
research, is open until 3:30 p.m. daily except
public holidays. Self-guided Economic Botany
Trail. Admission is by free permit (see
“HOURS”).

lES ECOLOGY SHOP
New in the Shop ... holiday candles ... blown glass
paperweights ... 1999 calendars ... cotton throws
... for children ... new shipment of Folkmanis
puppets ... lots of great books! ... and in the Plant
Room ... glass vases in wonderful new colors ...
kidskin gardening gloves ... copper planters.
Senior Citizens Da 3 fs: 10% off on Wednesdays
January Sale: from January 1-20, 50% off holiday
items, 20% off gifts, 10% off books
February Sale: 50% off all 1999 calendars
•• Gift Certificates are available ••

HOURS

Winter hours: October 1 - March 31
Public attractions are open Mon. - Sat.,

9 a.m.-4 p.m. & Sun. 1-4 p.m., with a free permit*.
(Note: The Greenhouse closes at 3:30 p.m. daily.)
The lES Ecology Shop is open Mon.- Fri., 1 la.m.-4
p.m., Sat. 9 a.m.-4 p.m. & Sun. 1-4 p.m. (The shop
is closed weekdays from 1-1:30 p.m.)

Holiday Hours

The lES Ecology Shop closes at 3 p.m. on Dec. 24
and Dec. 31 and is closed on Christmas and New
Year's Day. It is open as usual on the weekends of
Dec. 26-27, and Jan. 2-3.

* Free permits are required for visitors and are avaitable
at the lES Ecology Shop or the Education Program office
daily until 3 p.m.

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We have opportunities for volunteers in a number
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one-day-a-week Volunteer Program coordinator,
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assistants in the lES Ecology Shop. For informa-
tion on volunteering at lES, call Ms. Su Marcy at
914/677-5359.

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Join the Institute of Ecosystem Studies. Benefits
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rate for courses and excursions, a 10% discount
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membenship: $30; family membership: $40. Call
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members of Tbe Aldo Leopold Society are invited
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... for research, graduate opportunities, library
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Institute of Ecosystem Studies
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