(Flood Tolerance from page 1)

on the trunk near the water surface.
Species unable to maintain normal
roots or grow new ones quickly die.

Recovery — Rate of recovery
following drainage is a factor in
tolerance. Trees need to build up food
reserves for future stress conditions —
flood, drought, insects, and diseases —
and young trees must produce height
growth to get their foliage above flood
levels. Environmental conditions often
limit recovery. If the soil drains
rapidly, and soil moisture is main-
tained near field capacity, the
surviving root system will initiate new
growth and recovery will be rapid.
However, if the soil remains saturated,
the root system may deteriorate. At
the opposite extreme, if soils dry
quickly because of drought conditions,
adventitious roots may be of little
benefit. The tree is then dependent
upon survival of the secondary root
system.

Variations — Little is known about
tolerance variations within a species.
Flood tolerance may well be an
inherited trait that could explain the
discrepancies in reports on survival.

Determining flood tolerance is
further complicated by the diverse
characteristics of floods. These include:
the season, duration of flooding, water
level, left-over sedimentation, tempera-
ture and oxygen content of flood
waters, and mechanical injuries left by
the flood.

Trees often recover rapidly from
slight injuries, such as twig dieback.
Although flood injuries vary, other
early symptoms include leaf-tip and
stem twisting, red coloration, chlorosis,
and leaf wilting. Dieback of roots and
twigs and the formation of dead spots
in the bark may follow, and if flood-
ing continues, the entire tree
eventually dies. Some trees may not
follow this pattern; leaf wilting can be
followed directly by the death of the
tree. With these more severe injuries,
recovery may take a year or longer.
Reduction of vigor may render a tree
unusually susceptible to adverse
environmental conditions. Until vigor
is restored, such a tree is especially
susceptible to insect and disease
attacks, drought, and additional flood-
ing.

Source: Adapted from “Flood-Tolerant Tree,"
Joumal of Forestry, March, 1987, by William L.

Loucks, Extension Forester, Environmental

Forestry, Department of Forestry,
Kansas State University.

(Water Quality from page 1)

rivers, and lakes.

Riparian forests provide this buffer
zone. Extremely complex ecosystems,
riparian forests play a major role in
controlling nonpoint source pollution.

Riparian Areas

Recent research has shown that
riparian forests improve the quality of
water resources in several ways. They
function simultaneously, as filters,
sources, transformers, and sinks.

As a filter, riparian forests remove
sediment and other suspended solids
from surface runoff. Sediment is the
most common and most easily recog-
nized of nonpoint source pollutants.
Sediments suspended in water reduce
or block penetration of sunlight,
thereby adversely affecting the growth
and reproduction of beneficial aquatic
plants.

Sediment deposited on stream
bottoms interfere with the feeding and
reproduction of bottom dwelling fish
and aquatic insects, weakening the
food chain. Large deposits of sediment
fill river and stream channels and
floodplains, thereby increasing the
potential for flooding.

Several mechanisms of sediment
removal are at work in the riparian
forest. Some sediment settles as the
flow speed is reduced by the many
obstructions encountered in the forest
litter. Additional sediment is filtered
by the porous soil structure, vegetation,
and organic litter as the runoff flows
over and into the floor of the forest.

Phosphorous is also reduced by the
filtering action of the forest. Since
phosphorous will bond to small soil
Particles, approximately 80 percent can
be trapped with the soil particles as
they move through the forest buffer.

Riparian forests function as a
source when they provide energy to
streams in the form of dissolved
carbon compounds and particulate
organic detritus. These materials are
critical to processes within the stream
itself, helping to restore and maintain
nature’s equilibrium. Benthic
detritivores, the stream bottom bacteria,
fungi, and invertebrates that feed on
the detritus, form the basis of the
aquatic food chain. They pass on
energy when they are consumed in
tum by larger benthic fauna and
eventually by fish. Thus, the stream-
side forest functions as an important
energy source for the entire aquatic
food chain from the headwaters to

estuary.

Riparian forest buffers function as a
transformer when chemical and
biological processes occurring within
the forest change the chemical compo-
sition of compounds. For example,
under oxygenated soil conditions,
bacteria and fungi in riparian forests
convert nitrogen in runoff into mineral
forms. These forms of nitrogen then
are synthesized into proteins by plants
or bacteria. When soil moisture creates
aerobic conditions in the litter and
surface soil layers, denitrifying bacteria
convert dissolved nitrogen into various
nitrogen gases, returning the gases to
the atmosphere.

These forests also transform toxic
chemicals such as pesticides to non-
toxic forms. Because of continued
improvements in the formulation and
management of pesticides, only small
amounts leave the area of application.
Pesticides in runoff are converted to
non-toxic compounds by microbial
decomposition, oxidation, reduction,
hydrolysis, solar radiation, and other
biodegrading forces at work in the soil
and litter of riparian forests. While
scientists have understood the biologi-
cal processes at work in the forest,
additional data are necessary to fully
quantify their importance with respect
to pesticide degradation.

Finally, riparian forests can function
as a sink when nutrients are taken up
by plants and sequestered in plant
tissue. Estimates indicate 25 percent of
nitrogen removed by forests assimilated
in tree growth, which is stored for
extended periods of time in woody
tissue and possibly removed as logs or
other forest products. Nitrogen and
other nutrients also pass through the
food chain when plant tissues are
consumed by animals and converted to
animal tissues. In wetter areas, nutri-
ents in leaf litter can be stored for
longer periods as peat.

There are other benefits of riparian
forests that are easier understood, such
as wildlife habitat, recreation, aesthet-
ics, and timber production, but the
benefits less often seen, like improving
nonpoint source pollution, could be the
most important to humankind in the
long haul.

Source: Growing Green Forestry Newsletter,
July/August, 1993



Nieease lowa

Hospital Gets 2,900-Tree Windbreak

Editor's note: The Agroforestry Center is working with
numerous cooperators throughout the Great Plains to
establish demonstrations of needed agroforestry practices
under local conditions. This article illustrates the value that
the demonstrations will have to the economy, environment,
and people.

Even with all of the flooding in Iowa this spring and
summer, Woodward State Hospital and School in
Woodward, Iowa, got its windbreak. Over 362 full-time
mentally and physically handicapped residents and about 800
full-time local employees will benefit from the renovation
and expansion of a
declining two-row wind-
break around their facility.

The hospital is
located on 80 to 90 acres
of ground and is the
largest employer in the
area, It contains local
industry, classrooms, and
living quarters for em-
Pployees and patients. In
cooperation with the Iowa
Department of Natural
Resources and the Center

Woodward State Hospital and School

gave up approximately 11 acres of

high-quality farmground to plant the
2,900 tree windbreak which stretches
2 U2 miles around the entire facility.

for Semiarid Agroforestry,
the hospital has expanded
a struggling two-row

honeysuckle windbreak by

adding two rows of
eastern red cedar and one row of a norway spruce/white
pine combination.

One of the things that John Walkowiak, Urban Forester
with the Iowa Department of Natural Resources, really likes
about the project is its large size. He says that the grounds
are like a community in itself and in order to expand the
windbreak, the facility gave up approximately 11 acres of

The struggling two-row honeysuckle windbreak around Woodward State
Hospital and School has been expanded into five rows by adding two rows
of eastern red cedar and one row of a norway spruce/white pine combina-
tion.

high-quality farmground. The break will now stretch 2 1/2
miles around the entire facility and will add much needed
density and height to the existing windbreak.

Despite the constant rain, 2,900 trees were planted the
first week of May during a three-day dry spell. Walkowiak
says that “I sure wish that the weather would give us a
break” because inbetween storms they are still trying to put
down the remaining 1/3 of the fabric weed barrier that
needs to be applied. As of this writing, they have had a 90
percent tree survival rate and haven’t had to water the trees
much yet.

Wood chip mulch will be put on part of the break while
the remainder will be left uncovered. This will be a good
test to see if wood mulch is needed, in combination with
light or dark colored fabric, to minimize weed competition.
So far, with the abundant rainfall, the light colored fabric
has held up well. However, in some places grass is growing

New Hope for Chestnuts and Elms ——

A breakthrough discovery by scientists at the Roche Institute of
Molecular Biology could result in restoring native chestnuts to the Ameri-
can landscape. Chestnuts have virtually disappeared since a fungal disease
was accidentally introduced from Asia in 1904. The new discovery uses a
genetically engineered virus that alters the genetic makeup of the chestnut-
killing fungus, reducing its virulence. Because of the reproductive abilities
of the blight-fighting virus, scientists hope that once introduced, it will
spread naturally, enabling the return of American chestnuts. The method
used for manipulating the genetic machinery of these microscopic organ-
isms also shows promise for use as a natural control of Dutch elm
disease and various agricultural disease problems. Permission for green-
house and field trials is being sought from the USDA, with three to five
years predicted for completion of the tests.

Source: Arbor Day, January/February, 1993

underneath and has pushed the fabric
up. Late this summer, plans were to
to restable and put down one to two
inches of wood mulch.

The windbreak will provide wind
and snow protection, beautify the
landscape, and increase wildlife habitat
for the hospital. It will aid in reduc-
ing utility bills, conserving energy, and
lowering snow removal costs. The
planting and maintenance will primari-
ly be supplied by the normal grounds
crew but will involve some of the
residents that are physically capable of
volunteering.

The project will further serve as a
technology transfer demonstration site
of proper use of conservation forestry
tree planting and maintenance for use
by natural resource professionals and
as a public awareness demonstration
for what conservation tree plantings
can do for communities.



The Flood-Tolerance
of Trees

Physiological responses and tolerance
mechanisms of trees to flooding were
studied extensively from the 1940’s
through the mid-1970’s. These studies
helped foresters understand the impact
of flooding on trees and suggested
future investigations. But the state-of-
the-art has not developed sufficiently
to issue a precise statement on the
adaptability of a species to a specific
flooding situation. In fact, conclusions
are often at variance.

Such apparent discrepancies are
caused by the physiological responses
of the tee as it interacts with envi-
ronmental conditions. Since these
interactions are not well understood,
predictions of flood tolerance must be
in general terms. A look at tree and
flood characteristics indicates the
complexity of interactions. Various
characteristics of a tree and how they
affect tolerance to floods follow:

Height — Tree height, as compared
to water depth, is the most obvious.
Injury increases as water covers
foliage. Some species that survive
months standing in several feet of
water may succumb in less than a
month when foliage is completely
covered.

Vigor — Flood tolerance generally
increases with the age of the tree,
until it begins to lose vigor with
overmaturity. Healthy, vigorous trees
show the greatest resistance to flooding
and saturated soil. Both the very small
and overmature tree classes show the
greatest susceptibility. Insect and
disease attacks and adverse soil
conditions also affect vigor, as do
excessively wet or dry soils or soils
with poor permeability.

Roots — Survival and growth of
flooded roots are indicative of a
species’ ability to adjust to long
periods of floods. Some species main-
tain normal roots in an active or
dormant condition. Others rely upon
new secondary and adventitious roots
that may form from the root collar or

(See Flood Tolerance on page 5)

5

iparian Buffer Zone

Herbicide and Fertilizer
Addition

Herbicide and Fertilizer Uptake
and Filtering By Root System

roforestry

USDA Forest Service, Lincoln, Nebraska

Fall, 1993

Other Benefits:
Soil Conservation
Wildlife
Biodiversity
Wood Products

Clean Water

ee
AS

The Growing Concern Over Water Quality

For the past several decades, water
quality has been a growing concern
worldwide. In the United States, the
concern has heightened enough to
prompt legislative action to deal with
the problem.

The Water Pollution Control Act of
1948, or “Clean Water Act”, and its
subsequent amendments through 1987
have demonstrated strong Congressional
determination to improve the quality of
our water resources. These laws aided
the identification and clean-up of point
source contaminants by requiring states
to establish and enforce water quality
standards by requiring specifications
and licensing for discharge of effluents
and by funding the installation of
municipal sewage treatment plants.

With the point source pollutant
problem improving, attention has now
tured to a more difficult problem,

This Issue

addressing nonpoint source pollution.
Nonpoint source pollutants are more
difficult to trace to specific locations
since they enter our water supply as
components of run-off and ground
water flow. Currently, nonpoint source
pollutants such as sediment, nutrients,
pesticides, herbicides, and animal
wastes account for more than 75
percent of the pollution in our na-
tion’s waters.

Best Defense
Although there has been intensive
efforts to reduce fertilizer application
in fields, we are still faced with the
impossibility of stopping all erosion of
sediments, chemicals, and wastes from
upland sites. In addition to in-field
practices, we still need to provide
buffer or catch zones for these pollut-
ants before they reach our streams,
(See Water Quality on page 5)

TM@ Message from the Manager...page 2

Call for Poster Papers —'94 Symposium...page 2
A Kansas View on Agroforestry and Water Quality...page 3

Towa Windbreak Planted Despite Rain...page 4


Message From the Manager

As we wind up our second fiscal year as a Center,
there are a lot of accomplishments to reflect on. We
have finally reached the stage where we are reporting to
you what we are accomplishing, rather than what we are
preparing to do. Also, it's important to emphasize that
it's a capital WE, because most of the accomplishments
are team accomplishments — Center research and tech-
nology transfer folks working together with numerous
cooperators and partners.

As envisioned, the Center is now a fully integrated
program, linking the activities of Forest Service Research
and State and Private Forestry (S&PF) — in support of
our mission to advance the use of agroforestry in sustain-
able land use systems. This is a cornerstone accomplish-
ment, and we greatfully acknowledge the support and
committment to agroforestry from S&PF. We feel strongly
that this “Center of Excellence” approach will enhance
efficiency and leverage funding through partnerships and
client involvement, for everyone’s benefit.

We accomplish the Center’s research mandates in two
ways: 1) in-house research by our Research Work Unit,
and 2) through multidisciplinary research teams. The in-
house research effort is solidly on track developing
genetically stress and pest resistant, multi-purpose conser-
vation trees and tree health management systems for rural
and community environments. During the past year we
have made great progress in forming multidisciplinary
research teams to accomplish our additional research
responsibilities mandated in the 1990 Farm Bill. These
teams include: 1) riparian buffer systems — to protect
water quality; 2) modeling of agroforestry systems — to
evaluate the benefits of agroforestry under different
climate change scenarios; 3) drought tolerance screening
— application of ecophysiology techniques to accelerate
screening tree genotypes for drought tolerance; 4) propa-
gation of genetically pest resistant conservation trees; 5)
interactions between agroforestry systems and agricultural
crops; and 6) integrated conservation/production systems

A column of important events and programs
as reported by CSA Program Manager Bill Rietveld

It's Been A Big Year

— a cooperative agroforestry R&D effort with INIFAP
scientists in northern Mexico. The basic formula for these
teams, consisting of university, agency, and NGO partners,
is to focus on a project, obtain funding from various
sources, and do the work together. These team efforts
leverage our funding and human resources two to one,
and will support numerous graduate students, post-docs,
interns, and university faculty working together to attain
team goals. The role of the Center is to catalyze and
facilitate these team efforts.

Noteworthy technology transfer accomplishments to
date include: establishing 18 cost-shared agroforestry
demonstrations in ten states and funding another 20 in
eight states, to be established next spring (38 total to
date); contracting eight assessments of the potential of
agroforestry in sustainable land-use systems; and a “Work-
ing Trees in Agriculture” display and leaflet (in
cooperation with Northeastern Area S&PF) for the Nation-
al Farm Progress Show. Attendance at the show is
expected to surpass 300,000. Again, it is important to
emphasize that these are team accomplishments that would
not be possible without the vital support and participation
by State Foresters, Soil Conservation Service, Soil and
Water Conservation Districts, university cooperators, and
State and Private Forestry specialists in Washington, D.C.,
Forest Service Regions and Northeastem Area. In addition,
the Center has maintained the flow of current and useful
information in the form of Inside Agroforestry, our
quarterly newsletter, articles in other newsletters, publica-
tions, presentations, news releases, and a
soon-to-be-released conservation tree planting video.

With new partnerships being formed, we expect the
accomplishments to increase geometrically in future years.
I’m very excited and proud of what has been accom-
plished so far and the prospects for the future. People
wonder how our small team can accomplish so much.
The answer is, it’s a capital WE (teamwork), plus in-
volvement, partnerships, cooperation, and networking.

Agroforestry and Sustainable Systems — Call for Poster Papers

Agroforestry and Sustainable Sys-
tems, a symposium designed for
researchers, practitioners, technical
specialists, and educators, will be held
August 7-10, 1994 in Fort Collins,
Colorado. It will focus on how trees,
integrated into sustainable agricultural
land-use systems in the semiarid west,
will enhance agricultural productivity,
natural resource conservation, and
natural and human environments.

activities.

tives and results.

Symposium sponsors invite submis-
sion of volunteer poster papers that
address the general theme of
Agroforestry and Sustainable Systems.
Papers may report domestic research,
technology transfer, innovative applica-
tions, surveys, education, and training

The abstract should be no longer
than one page and emphasize objec-

Due to limited space available,
all posters must be submitted for
approval by February 15, 1994.
Final abstracts are due by May 1,
1994,

To submit an abstract or for more informa-
tion on poster papers, contact: Bruce C. Wight,
SCS, National Windbreak Forester, 100 Centenni-
al Mall North, Room 152, Lincoln, NE 68508-
5315, 402-437-5315.

For more information on the Symposium,
contact: Kim Isaacson at the Center.

2



Agroforestry's Role in Clean Water — A Kansas Point of View

By John K. Strickler
Extension Forester, State and Extension Forestry
Kansas State University

The role of forest lands and
forestry practices on water quality and
quantity in forested watersheds has
been well researched and documented.
However, the role of Great Plains
forests and their management from the
water quality standpoint has not been
well researched nor given extensive
consideration. Perhaps because of the
relatively scarce and scattered nature
of forests in the Plains, it was felt
that their impact on water quality
would be quite minor. Yet, I hope to
encourage you to give this issue more
thought and consideration.

“There is little doubt
in my mind that
water quality and quantity
issues are going to be
one of the major,
if not the major,
driving force in Great Plains
agriculture in the '90's.?
— John K. Strickler

There is little doubt in my mind
that water quality and quantity issues
are going to be one of the major, if
not the major, driving force in Great
Plains agriculture in the '90’s. More
specifically, the issue of forestry and
nonpoint source pollution is the water
quality issue that agriculture and
forestry must address.

When we in Kansas hear the term
“nonpoint source pollution,” we tend
to think of our major land uses —
agricultural cropping with associated
soil erosion and fertilizer and pesticide
use — or maybe urban runoff. We
seldom think much about trees and
forests as a factor. Yet, while making
up only three percent of the total land
area in Kansas, forests can play a
significant role in the control of
nonpoint source pollution. Most
significant are the streamside or
tiparian woodlands that are receiving
increased attention nationwide.

In the Great Plains, the bulk of the
natural forests occur as riparian
vegetation adjacent to streams. These
woodlands are a buffer between the
stream channel and the major land use

-- cropland, range, or pastureland in
most cases. In eastern Kansas, these
riparian forests are more extensive, but
as we move west, they become more
closely confined to the streambanks. In
more arid regions, the riparian vegeta-
tion often becomes shrubs and native
grasses.

Riparian forests or buffer strips
lying between the stream and cropland
have a number of positive effects on
water quality. They:

e Tend to slow and spread the
water flow during flooding, leading to
silt deposition within the riparian zone
rather than in the stream.

e Act as filter strips by trapping
sediment and absorbing water runoff
from adjacent cropland before it
reaches the stream.

e Serve as buffers or traps to hold
nutrients and pesticides from overland
runoff and shallow groundwater zones.
One study showed wooded riparian
areas as narrow as 50 feet wide
removed most nitrogen flowing through
from cropland.

e Stabilize streambanks and thus
reduce the sediment load created by
rapid bank erosion.

e Provide extremely valuable wildlife
habitat — for both game and non-
game species, including migratory
songbirds. These streamside forests
support the most diverse variety of
wildlife of any habitat type in the
Great Plains.

e Help to make streams suitable for
diverse fish and aquatic populations.
By shading and maintaining lower
water temperatures in summer and
higher temperatures in winter, these
forests create a more suitable climate
for complex aquatic ecosystems.

e Provide other benefits such as
timber products and recreation.

I am suggesting here that forested
buffer or filter strips should be consid-
ered as a possible best management
practice (BMP) for cropland to reduce
nonpoint source pollution. Retention
and establishment of riparian forests
are factors that should be part of
many water protection plans in the
Great Plains.

The first priority on accomplishing
this should be on maintaining and
properly managing existing riparian
forests. Clearing vegetation and
channelizing streams create serious
erosion and flooding problems and the

solutions are very costly. Where
riparian vegetation has been eliminat-
ed, re-establishment of forested filter.
strips is an option that should be
considered. On the other hand, reten-
tion and proper management of these
forests is relatively cheap and easy.
Proper management can provide for
selective and controlled harvesting of
timber, though within the immediate
streamside zone, water quality consid-
erations should be given top priority.

Grazing in riparian forests is
another issue I'd like to address.
Restriction, or preferably elimination of
grazing from riparian woodlands can
be highly beneficial to water quality.
Grazing eliminates ground cover and
natural forest reproduction as well as
greatly diminishing the absorption
qualities of forested soils.

Of course, cattle watering and
feeding in the riparian forest zone can
also contribute to water quality prob-
lems by providing direct entry of
livestock waste into the water. We
need to explore cost-share alternatives
and incentives to encourage landowners
to change grazing practices in stream-
side forests. These might include:

e Planting trees away from the
riparian zone to provide alternative
livestock shelter.

e Cost-sharing for fencing of
riparian zones to exclude livestock.

e Cost-sharing on alternative water
supplies away from the stream.

I realize that this will not receive
instant acceptance, but if we are
serious about non-point source pollu-
tion, we have to objectively look at
alternatives to current practices.

I also realize that the emphasis in
many cases on nonpoint source pollu-
tion is going to be on cropland
treatment and management — as it
should be. We Great Plains foresters
are used to being considered a little
different or odd in an agriculturally
dominated environment. But I would
urge you to give full consideration to
the role that trees, forests, and forestry
can play in Great Plains water quality
efforts. They can be valuable and
useful tools as we address the
nonpoint source pollution problem. In
fact, I believe that the interface of the
water quality issue with forests pre-
sents one of the greatest opportunities
for Great Plains forestry in all of my
32 years in Kansas.

3