Newsletter

Volume 7, Number 5
September - October 1990

Director’s Note

The Carriage House, behind the Perennial
Garden, used to be a stable. In “A Gifford
House Memory Sampler,” Sally Gifford
O’Brien wrote that the building had “six box
stalls, a tack room, a three-car garage, a small
tool room, the hay loft and a pigeon loft.”
When the Arboretum bought the property in
1974, the Carriage House was remodeled to
provide storage space.

This structure has been completely renovated
over the past six months by the Institute's very
capable maintenance staff. Where there used to
be storage areas for tools and equipment there
is now an exhibit room where school groups
learn about acid rain and where more educa-
tional exhibits will be set up in the coming
months. Where there used to be a dingy,
concrete-floored space to keep tractors and
gardening supplies, there is now a bright,
wood-floored classroom for IBS Continuing
Education Program classes. We hope that our
students and visitors will enjoy this new edu-
cation facility.

Exploring Human Impact on Landscapes

Fire . . .

Flood . . .

Grazing . . .

Humans . . .

. . . What do these have in common ?

Although in one way this list looks as if
it should be a “Which does not belong?”
question from a child’s workbook, these
four things do have something in common:
each has the ability to wreak havoc on an
ecosystem. Ecosystem disturbance and
recovery is an area of study for a number
of ecologists at the Institute of Ecosystem
Studies and elsewhere, and one ecologist
who has directed his studies of ecosystem
disturbance to focus on the effects of

be part of the explanation for this discrep-
ancy. Herbivory on seedlings by introduced
rabbits, hares and goats in one area, for
example, might explain differences in
shrub communities between that area and
one that is ecologically similar but without
introduced herbivores.

Humans introduce non-native herbivores to
a landscape. Humans also introduce annual
grasses, and cause other major ecosystem
disturbance by clearing and burning fields
for agriculture. To try to determine more
precisely the role of humans in the chang-
ing landscape. Dr. Fuentes shifted his
research focus to landscape ecology which
looks at the geographical expression of the
relationship between cultural practices and

Drs. Mark McDonnell, Eduardo Fuentes and Steward Pickett worked together at an international
workshop in Chile last January. In September, at lES, they planned future resarch in the field of
landscape ecology.

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

humans on landscapes is Dr. Eduardo E.
Fuentes, the Institute’s 1990 Cary Summer
Research Fellow.

Dr. Fuentes, a professor of ecology at the
Pontificia Universidad Catolica de Chile
and Universidad de Chile, began his
scientific career as an ecological zoologist,
doing comparative field studies in the area
around Santiago, Chile and in southern
California. These two sites have very
different biological histories but remark-
ably similar environments. Dr. Fuentes’
goal was to learn more about ecological
convergence, the phenomenon in which
organisms from different regions develop
similar characteristics due to adaptations
and constraints imposed by similar envi-
ronments. It was found that certain groups
of organisms show ecological convergence
while others do not, and Dr. Fuentes
reasoned that indirect human effects, such
as introduction of non-native species, could

biology. He is now studying changes in
the central Chilean landscape since the
arrival of Europeans some 500 years ago,
and adding to his understanding of the
historical role of humans by collecting data
on the elimination of some species, the in-
troduction of other species, the changes in
plant cover and the erosion of soils.

What kinds of detective work are used to
learn enough about landscapes to be able
to recognize, and suggest causes for,
changes that have occurred over centuries?
Dr. Fuentes combines a number of tech-
niques. He reads historical reports about
how the landscapes used to look, and
studies photographs from the past. He also
compares disturbed sites with areas that
look less disturbed and with similar ecosys-
tems elsewhere in the world, to look for
telltale differences.

continued on page 3

Research Experiences for Undergraduates, Part 2

Sophisticated student research. This
phrase describes the three months of
creative scientific thinking and hard work
done at the Institute of Ecosystem Studies’
laboratories by nine college undergraduates
this past summer. In the last issue of the
lES Newsletter, the research by three of
these students was described: two of the
students worked with Dr. Clive Jones and
studied plants’ chemical defenses against
insects, while one worked with Drs.
Margaret Carreiro and Steward Pickett to
learn whether fungi — microorganisms
that decay organic matter — grow more
successfully in rural than in polluted urban
areas. All nine students were participants
in the third year of a Research Experiences
for Undergraduates (REU) Program at the
Institute, a program sponsored by the
National Science Foundation (NSF) in
its efforts to stimulate and support college
student interest in the sciences.

Following are summaries of the work by
the other students:

JENNIFER A. ALTRE, Cornell
University, Ithaca, N.Y.

Mentor: Dr. Richard S. Ostfeld.

Meadow voles (Microtus pennsylvanicus)
are small rodents related to lemmings,
mice, rats, hamsters and gerbils. In the
Northeast, female voles are aggressive
and territorial while the males are less
aggressive and tend to wander. During
the summer voles are prolific, and as the
population increases certain animals move
to areas that are less desirable and therefore
less inhabited. Which animals migrate to
these new environments as the prime areas
become too crowded? Ms. Altre’s hypo-
thesis was that adult males and juveniles of
both sexes would be the ones to move, and
she hoped that data resulting from her
study would help determine how habitat
patchiness relates to the social structure
of these animals.

In the field site — an area near the Green-
house with patches of pasture and little
bluestem grass meadow — Ms. Altre laid
out 169 live-traps in a grid 90 m (close to
300 ft.) on a side. Traps were set in the
afternoon, baited with oats and provided
with cotton so animals would be warm,
then checked the following morning when
the trapped voles were sexed, weighed,
tagged and released at the site of capture.
When she analyzed her nine weeks of data,
Ms. Altre found differences between
patches: while there was a greater popula-
tion density, recruitment rate (influx of
new voles due to reproduction or immigra-
tion) and probability of survival in the

pasture, female territoriality was evident
only in the meadow.

LAURA B. BYBEE, The University of the
South, Sewanee, Tenn.

Mentors: Drs. Alan R. Berkowitz and
Charles D. Canham.

lES ecologists studying growth of vegeta-
tion along utility company rights of way
are interested in knowing if root systems
of tree seedlings respond to environmental
stresses by an increase or decrease in
growth or branching frequency. Working
in the Greenhouse, Ms. Bybee planted red
oak and red maple seeds in sand, and grew
the seedlings for a month. The plants were
grown at normal and high shade levels,
with normal and low amounts of nitrogen
(administered in a nutrient solution) and
with varying amounts of water. After
harvesting the seedlings, which by then
were 2.5 - 10 cm (1-4 in.) tall, Ms. Bybee
washed, dried and weighed their roots.
Seedling root system responses to stress
(low levels of light, nitrogen and water)
were evident, but not highly significant
over short growth intervals. She found that

root growth increased in response to both
nitrogen and water stress (low levels of
these growth resources), while it decreased
at high shade levels.

SUSAN M. KAMINS, Antioch College,
Yellow Springs, Ohio, and
EMILIO MAYORGA, Massachusetts
Institute of Technology, Boston, Mass.
Mentors: Drs. David L. Strayer and
Stuart E.G. Findlay.

Ms. Kamins and Mr. Mayorga worked on
two different aspects of a section of the
East Branch of Wappinger Creek at which
a bend in tbe streambed allows a “detour”
of water from the creek, through a gravel
bar, and back to the creek. While the
former looked at the interstitial (between
sand grains or sediment particles), inverte-
brate and microbial communities, the latter
measured the flow path and the chemistry
of the interstitial water. Twelve Plexiglas
wells (1.3 cm (0.5 in.) in diameter and 1 m
(3.3 ft.) deep) were placed along a transect
extending from the point upstream where
stream water filters into the groundwater of
continued on page 3

DIANA R. LANE, Harvard University,
Cambridge, Mass.

Mentors: Drs. Alan R. Berkowitz and
Charles D. Canham.

What makes tree seedlings grow better
or worse in any particular location? The
answer to this question is being sought by
ecologists with the Institute’s long-term
study of plant growth and ecological re-
lationships along utility rights-of-way.
The local conditions where the seedling

grows may be an important determining
factor, and Ms. Lane’s study dealt with
the plant’s “microsite” to see how light,
soil moisture and competition from
neighboring plants might mean success
or failure.

She worked with red maple seedlings
because red maple trees are the most
common invaders of rights-of-way in this
area. Her microsites were 15 cm (6 in.)
diameter circles around each seedling,
and were established in
three fields of varying
moisture levels on the
Arboretum. Her data
showed that, within a
field, variation in seedling
growth did not correlate
with variations within
the microsites. Seedling
response to overall dif-
ferences in site quality,
i.e., the light, soil moisture
and degree of plant com-
petition present in the
whole field, superseded
any pattern of response
to microsite variation.

REU student Diana Lane and
one of her lES mentors,

Dr. Alan Berkowitz, test the
Sunfleck Ceptometer that was
used to measure light levels in
the microsites.

REU Program , from page 2

The profile of the Plant Science Building has changed. A new roof completed during the past
summer, became necessary to correct serious leaks in the original roof. Architect Jim Flynn
designed the new roof and construction was done by R.W. Ciferri, Inc. of Millbrook.

the gravel bar to the point downstream
where groundwater discharges back into
the stream. All data were collected at these
sites. The purpose of the study was to learn
about the subsurface ecology of the gravel
bar ... the relationships between interstitial
organisms and their physical environment.

Using sediment cores collected along the
transect, Ms. Kamins determined the
amount of microbial activity, collected the
animals and identified them under a micro-
scope, measured sand grain size, and noted
the amount of solid organic matter that
there was in the sediments. Her data
showed that at the upstream end there are
coarser sediments and larval and nymph
forms of aquatic insects. Downstream, the
sediments are fine, and nematodes —
roundworms — are common. Copepods,
mites and other microscopic crustaceans
are found in both places. Ms. Kamins
returned to school with data yet to be
analyzed . . . data that she hopes will help
to explain why there is little organic matter
in the center of the gravel bar and why
there isn’t a continuum of change in the
communities of gravel bar organisms.

Mr. Mayorga studied the physical and
chemical characteristics of the ground-
water. He measured water pressure
differences at the wells to determine
whether or not there was actual flow of the
interstitial water, and found that the flow
was considerable. Also, using a pump to
collect water from the wells, he analyzed
the water chemistry including the pH
(level of acidity or alkalinity), dissolved
oxygen, dissolved organic carbon and
nitrates. Using this chemical data, he was
able to determine several interesting things.
First, changes in water chemistry from the
upstream end of the bar to the downstream
end showed the presence of an active
subsurface biological community. Also,
the data showed that interstitial water
flow did, indeed, have its origin in the
stream and was not due to infiltration by
“true” groundwater from the adjacent
stream bank.

Background data collected by Ms. Kamins
and Mr. Mayorga will provide the founda-
tion on which more detailed studies of the
biological communities of shallow ground-
waters will be based.

KRISTINA STINSON, Bennington College,
Bennington, Vt.

Mentor: Dr. Clive G. Jones.

Changes in leaf chemistry following herbi-
vore damage are known as “defensive” or
“induced” responses. These changes have
been shown to increase a plant’s resistance

to further herbivore attack by reducing
insect preference for induced leaves.

Ms. Stinson wanted to learn more about
how insects respond to previous herbivory
on plants.

Using cottonwood tree seedlings damaged
by the willow leaf beetle or by mechanical
means (a metal file), she observed the feed-
ing behavior of adult leaf beetles on both
types of damaged leaves and on undam-
aged control leaves. Regardless of the
cause of the damage, the beetles preferred
feeding on undamaged leaves. A similar
pattern occurred in leaves closely con-
nected (on the original plant) to damaged
or control leaves. A theory is that leaf
damage results in the release of phenol-gly-
cosides, defensive chemicals found in some
plants, and it is also possible that the
cottonwood vascular system carries the
phenol-glycosides throughout the plant.

A collection of the REU students’ papers
describing summer 1990 research and
results, as well as reports of 1988 and
1989 REU studies, will be available as
lES Occasional Publications.

Human Impact, from page 1

For example, in the Chilean mountains
there used to be a belt of trees — a species
of conifer whose wood was good for
construction — that is now almost com-
pletely gone from the area near Santiago.
Ecologically similar areas in Southern
California and the Mediterranean each
have a conifer belt. Why have seedlings
survived and reached maturity there? A
possible explanation is that in Chile, after
the adult conifers had been cut for use in

the building industry, rabbits and hares that
had been introduced by European settlers
moved into the newly opened areas and ate
the seedlings, leaving no new trees to
reestablish the forest.

Finally, Dr. Fuentes does experiments to
see if past ecological conditions can be
duplicated. Suppose he wants to explain
why the seedlings of native shrubs are
drying out in summer. He hypothesizes that
fast-growing annual grasses introduced
from Europe compete more successfully
for water. He tests this hypothesis by
growing the same seedlings under identical
environmental conditions but without
introduced grasses present. An interesting
sidelight: Chilean farmers lend him the
land, and often workers and materials as
well, for his ecological field studies.

Dr. Fuentes was invited to apply for the
Cary Summer Research Fellowship
when he met lES ecologists Dr. Gene E.
Likens, Dr. Juan J. Armesto (lES Adjunct
Research Associate, Universidad de Chile)
and Dr. Steward T. A. Pickett at an inter-
national workshop held early this year in
Chilian, Chile (lES NEWSLETTER
March-April 1990). He received the
award and spent a month here in late
summer, interacting with Institute ecolo-
gists on issues relating to landscape
ecology, writing reports of his research
and collaborating on two papers with
Dr. Mark J. McDonnell. The latter were
“ideas papers,” Dr. Fuentes explained,
about what landscape ecology is and
how it could contribute to comparative
studies of temperate evergreen rainforests
in Southern Chile and the Northwestern
U.S. The papers will be published as
part of the proceedings from the Chilian
meetings. Dr. Fuentes looks forward
to continued collaboration with
lES ecologists.

At the Greenhouse

During December, visitors to the green-
house might look for the large and unusual
ponderosa lemons {Citrus ponderosa)
and bird-of-paradise flowers (Strelitzia
reginae). In late January, the begonias of
the Kolker Collection begin to bloom,
while orchids start to flower in February.

The bird-of-paradise, a flowering plant that is
native to South Africa, is blooming in the lES
Greenhouse.

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

Winter Calendar

CONTINUING EDUCATION
PROGRAM

If you would like to receive a free catalogue of
Winter and Spring Semester classes, workshops
and ecological excursions but are not on our
Continuing Education Program mailing list, please
call the office at the number below.

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.

There will be no program on December 16.
Programs scheduled for January 6 and 20, 1991, as
well as for February and March, will be listed in
the next issue of the Newsletter.

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.

Dec. 7: Soil Microbial Nitrogen Dynamics in
California Conifer and Grassland Systems, by
Dr. Mary Firestone, Univ. of California, Berkeley
Dec. 14: Plant Microbial Interactions in
Nutrient Cycling, by Dr. Eldor Paul, Michigan
State Univ., East Lansing
Jan. 11: Title to be announced. Speaker: Dr.
Thomas T. Veblen, University of Colorado,
Boulder

Jan. 18: Recent Work in Understanding the
Ecology of Land Mosaics: Boundaries,
Corridors, Graph Theory, Fragmentation, and
Land Conversion, by Dr. Richard T.T. Forman,
Harvard Univ.

Jan. 25: Coping with Predictable and
Unpredictable Habitat Deterioration: A Tale
of Two Moths, by Dr. Jeremy McNeil, Universite
Laval, Quebec

GIFT SHOP

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

Annual Pre-Holiday Sale: Friday, Saturday and
Sunday, December 7, 8 and 9.

Please note: The Gift Shop will be open on
Saturday and Sunday, December 22 and 23
(see hours below) for your last-minute holiday
shopping.

Annual Holiday Clearance Sale, throughout
January: 20% off on gifts and 10% on books,
with 50% off holiday items and candles.

ARBORETUM HOURS

(Winter Hours: October 1 - April 30;
closed on public holidays)

The Arboretum grounds are open Monday through
Saturday, 9 a.m. to 4 p.m.; Sunday 1 - 4 p.m.

The Gift and Plant Shop is open Tuesday through
Saturday 1 1 a.m. to 4 p.m. and Sunday 1 - 4 p.m.
(closed weekdays from 1 - 1:30 p.m.).

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.

MEMBERSHIP

Become a member of the Mary Flagler Cary
Arboretum. Benefits include a special member’s
rate for lES courses and excursions, a 1 0%
discount on purchases from the Gift Shop, a free
subscription to the lES NEWSLETTER, and
parking privileges and free admission to the
Enid A. Haupt Conservatory at The New York
Botanical Garden in the Bronx. Individual mem-
bership is $30; family membership is $40. For
information on memberships, contact Janice
Claiborne at (914) 677-5343.

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 5
September - October 1990

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