Just How Does A Windbreak Work? —

Windbreaks are barriers used to
reduce and redirect wind. They usual-
ly consist of trees and shrubs, but may
also be made up of perennial or annu-
al crops and grasses, fences, or other
materials. The reduction in wind
speed behind a windbreak modifies
the environmental conditions, or
microclimate, in the sheltered zone.

As wind blows against a wind-
break, air pressure builds up on the
windward side (the side towards the
wind), and large quantities of air
move up and over the top or around
the ends of the windbreak.
Windbreak structure — height, densi-
ty, number of rows, species composi-
tion, length, orientation, and continu-
ity — determine the effectiveness of a
windbreak in reducing wind speed
and altering the microclimate.

Windbreak height (H) is the most
important factor determining the
downwind area protected by a wind-
break. On the windward side of a
windbreak, wind speed reductions
are measurable upwind for a distance
of 2 to 5 times the height of the wind-
break (2H to 5H). On the leeward side
(the side away from the wind), wind
speed reductions occur up to 30H
downwind of the barrier. For exam-
ple, in a windbreak where the tallest

trees are 30 feet, lower wind speeds
are measurable for 60 to 150 feet on
the windward side, and up to 900 feet
on the leeward side! Within this pro-
tected zone, the structural characteris-
tics of a windbreak, especially densi-
ty, determine the extent of wind
speed reductions.

Windbreak density is the ratio of
the solid portion of the barrier, to the
total area of the barrier. Wind flows
through the open portions of a wind-
break. Thus, the more solid a wind-
break, the less wind that passes
through. Low pressure develops on
the leeward side of very dense wind-
breaks. This low pressure area behind
the windbreak pulls air coming over
the windbreak downward, creating
turbulence and reducing protection
downwind. As density decreases, the
amount of air passing through the
windbreak increases, moderating the
low pressure and turbulence, and
increasing the length of the down-
wind protected area. While this pro-
tected area is larger, the wind speed
reductions are not as great. By adjust-
ing windbreak density different wind
flow patterns and areas of protection
are established.

The number of rows, the distance
between trees, and the species compo-

causes the death of chestnuts.

Snails May Save Chestnuts —- :

There is renewed interest in utilizing chestnut trees in alley crop-
ping practices in the east. However, chestnut blight has deterred
using this species. At the start of this century over 4 million chestnuts
graced the woodlands of eastern United States. By 1950, 99.9 percent fell
victim to a deadly fungus. Today, researchers at the College of
Environmental Science and Forestry at Syracuse, New York, are optimistic
they are on the threshold of successfully breeding a blight resistant strain of
the American Chestnut. They are pinning their hopes largely on genetic
engineering and a fungus-eating snail called Helix pomatia, the same one
epicures eat as escargot. The genes and enzymes of the snail’s digestive
tract hold the secret to what causes anti-fungal activity in the snail. By iso-
lating a small protein that keeps fungal spores from germinating, it may be
possible to break the genetic code. Then, by introducing the resistant pro-
tein into chestnut cells and growing the cells into a full tree, the hope is that
the tree will have its own built-in defense system against the fungus that

Source: Adapted from Arbor Day, May/June, 1994.

sition are contributing factors to
windbreak density. When designing a
windbreak, density should be adjust-
ed to meet landowner objectives. A
windbreak density of 40 to 60 percent
provides the greatest downwind area
of protection and provides excellent
soil erosion control. To get even distri-
bution of snow across a field, densi-
ties of 25 to 35 percent are most effec-
tive, but may not provide sufficient
control of soil erosion.

Windbreaks are most effective
when oriented at right angles to pre-

(See Windbreak on page 6)

Table 1 — Windspeed reductions to the
lee of windbreaks with different densi-
ties. (H = mature tree height of the
tallest tree row).

Open Wind speed 20 mph
Deciduous 25-35% Density

H distance 5H 10H 15H 20H 30H
from break
mph 10 13 16 17 20
% of open

wind speed 50% 65% 80% 85% 100%

Open Wind speed 20 mph
Conifer 40-60% Density
H distance 5H 10H 15H 20H 30H
from break
mph 6 10 12 15 19
% of open
wind speed 30% 50% 60% 75% 95%

Open Wind speed 20 mph
Multi-row 60-80% Density

Hdistance 5H
from break

10H 15H 20H 30H

mph 5 7 13 #17 «19

% of open

wind speed 25% 35% 65% 85% 95%

Open Wind speed 20 mph
Solid Fence 100% Density

H distance 5H 10H 15H 20H 30H
from break
mph 5 14 18 19 20
% of open

wind speed 25% 70% 90% 95% 100%

Inside Agroforestry 5


Se eumenmeteeccs Minnesota

Windbreaks “Working” For Communities — = ——-

ia ren

=. & see
This small community is fortunate to have a windbreak Protecting its residents and is

typical of what the Prairie Country RC&D is encouraging.

It hasn’t taken long for rural community leaders in west-
central Minnesota to catch on to the benefits of the wind-
breaks that the Prairie Country Resource Conservation &
Development (RC&D) Council began promoting in 1992.

In fact, it’s easy to see the many benefits. First and fore-
most, there’s energy conservation (the main purpose of the
windbreaks), and the advantage of lowering snow removal
costs. Other benefits include education, recreation, and aes-
thetics.

It all started when the Prairie Country RC&D Council’s
Forestry Committee saw a need to plant windbreaks
around rural communities, which are mostly surrounded
by large expanses of cropland. The idea was a hit and
they’ve been promoting them ever since.

“We're just taking traditional rural applications of wind-
breaks and applying them to communities,” says Randy
Nelson, Coordinator for Prairie County RC&D, in Willmar,
Minnesota. “Picture a small rural community located in the
middle of corn and soybean country. Adjacent farmers
generally farm right up to the edge of town. Once crops are
harvested and the ground tilled, large expanses of barren
ground remain. Often times the first obstacle encountered
by wind and windblown snow is the unprotected commu-
nity.” Nelson says that basically these windbreaks, usually
located on the north and west sides of town, protect the
community in much the same way a field windbreak pro-
tects a crop or pasture or a farmstead windbreak protects a
homestead.

Initially, the Council asked area Soil and Water
Conservation Districts (SWCD’s) to speak with all of the
communities in their county. And, once several wind-
breaks were established in strategically located high vis-
ability areas, the good word spread. Now, town leaders are

ee contacting the Council about windbreaks!
: Currently five windbreaks have been plant-
ed with four more in the planning stage.

Most of the participating and interested
communities are fairly small in size and
consist of as few as 100 people to around
4,000 or 5,000 people. Thus far, the biggest
problem for these communities, who lack
the financial resources to put a project this
size on the ground, has been locating cost-
share funding. Almost 30 communites
throughout the nine-county Prairie Country
area are now interested in seeking funding
to put a windbreak around their town. The
main cost of the windbreak is actually
acquiring the land from area farmers. This
prime bean and corn farmland can sell for
$800 to at least $2,000 per acre! Several pro-
posals have been submitted to local power
companies, many of whom have an interest because of the
energy conservation component.

The Council relies on the local SWCD to assist with
design and species recommendations. Most of the wind-
breaks are made up of multiple rows consisting of ever-
greens, deciduous trees, and a trip row comprised of
shrubs. Typically, volunteers donate a great deal of in-kind
services like preparing the site, planting trees, or helping
out with maintenance.

Nelson feels that the potential is almost endless. “Once
the concept catches on, and more windbreaks are installed,
the community windbreak concept is sure to mushroom.”

New and innovative ideas like this take the initiative of people
like Randy Nelson, the Prairie Country RC&D Council and their
cooperators. Thank you, keep up the good work!

4

Prevailing Wind

Row! = 2 3 4 5 6 7 8

Dense Tall Shrubor Tall Tali Tall Tall Evergreen Evergreen
Shrub Medium Tree Tree Tree Tree Tree
<< — Usually Broad-Leaved >< Usually Evergreen al

Profile of a standard eight-row windbreak plan. The Prairie Country
RC&D generally follows a variation of this concept: shrub row(s), tall
tree row(s), with evergreens rows on the inside.

4. Inside Agroforestry



(Windbreak from page 5)

“Properly planned windbreaks
can create changes
in the microclimate
and can be used to create
desirable environments.”

vailing winds. The purpose and
design of each windbreak is unique,
thus the orientation of individual
windbreaks depends on the design
objectives. Farmsteads and feedlots
usually need protection from cold
winds and blowing snow or dust.
Orienting these windbreaks perpen-
dicular to the troublesome winter
wind direction provides the most use-
ful protection. Field crops usually
need protection from hot, dry sum-
mer winds and abrasive, wind-blown
soil particles, or both. The orientation
of these windbreaks should be per-
pendicular to prevailing winds dur-
ing critical growing periods.

Although the height of a wind-
break determines the extent of the
protected area downwind, the length
of a windbreak determines the
amount of total area receiving protec-
tion. For a maximum efficiency, the
uninterrupted length of a windbreak
should exceed the height by at least
10:1. This ratio reduces the influence
of end-turbulence on the total protect-
ed area. The continuity of a wind-
break also influences its efficiency.
Gaps in a windbreak become funnels
that concentrate wind flow, creating
areas on the downwind side of the
gap in which wind speeds often
exceed open field wind velocities.
Where there are gaps, the effective-
ness of the windbreak is diminished.
Lanes or field accesses through wind-
breaks should be located at an angle
to minimize this effect or, avoided all
together if possible.

The reduction in wind velocity
behind a windbreak leads to a change
in the microclimate within the pro-
tected zone. Many benefits result,
including an increase in temperature
and humidity levels, which decreases
evaporation of soil moisture and
plant water loss. Actual temperature
modifications for a given windbreak

6 Inside Agroforestry

Field Windbreaks Increase Wheat Yields in
1995

Wheat yields at the Univeristy of Nebraska-Lincoln research and devel-
opment facility near Mead, Nebraska showed significant yield differences
depending upon the amount of protection fields received from windbreaks.
The windbreaks did exactly what they were supposed to do in extreme
years, like 1995. Exposed plots without any wind protection had many
empty heads and showed extensive lodging. Crops in the sheltered plots
really looked good.

Exposed Plots
Plot Number Total Yield (bu) Acres Per Acre (bu)
1 170.0 8.5 20.0
2 116.0 7A 15.6
3 74.0 3.0 24.8
4 77.5 3.0 25.8
5 176.0 48 36.6
6 157.0 5.0 31.4
7 50.5 1.85 27.3
Average yield 25.9 (+ or-) 6.9

Sheltered Plots (Windbreaks on the west, south, and east) adjusted per
acre yield includes acres given to windbreaks.

Plot Number Total Yield(bu) Acres Per Acre (bu) Adj. Per Acre
1 221.0 40 55.2 49.1
2 200.5 3.8 52.8 46.6
3 213.3 4.0 53.3 474
4 217.6 40 54.4 48.3

Average yield 53.9 (+ or -) 1.1
Average yield based on adjusted acres 47.4 (+ or -) 1.3

depend on windbreak height,
density, orientation, and time of
day. Also, soil temperatures in
sheltered areas are usually
slightly warmer than in unshel-
tered areas. Taking advantage of
these warmer temperatures may
allow earlier planting and ger-
mination in areas with short

Proceedings now available from
the Agroforestry and Sustainable
Systems Symposium. For a free
copy, contact Dick Schneider at
the USDA Forest Service, Rocky

growing seasons. Mountain Forest &
Properly planned wind- Range Experiment
breaks can create changes in the 2
microclimate and canbe used to Station, 240 West
create desirable environments Prospect Road,
for growing crops, raising live- .
stock, and protecting the living Fort Collins,
and working areas. . Colorado 80526 /:
Source: Adapted from “How Windbreaks
Work” by James R. Brandle, University of Or call

Nebraska and Sherman Finch, Natural

Resources Conservation Service.

970-498-1719.



Inside fate

A forest service truck ‘carries trees taken from late 1930's Great Plains shelterbelt plantings |
in an early 1940's parade, proclaiming that trees actually do grow on the Plains and can |

“tame,” the Great American Desert.

The Biggest Windbreak

Project — Ever! —

It was around 1932 that some fel-
low in Washington D.C. spun a grand
dream of planting a belt of trees a
hundred miles wide, stretching
straight across the plains from
Canada to Texas. Lots of people
thought that towns would actually be
moved to make way for this mighty
forest, which at first grew only in the
Washington fellow’s mind...but grow
it did!

Officially called the Prairie States
Forestry Project, President Roosevelt
initiated the idea early in the summer
of 1934, and it was created by execu-
tive order on July 21st of the same
year. (Some have actually credited
President Roosevelt with originating
this idea). A decade of decreasing
agricultural income, prolonged
drought, a series of duststorms, and
finally economic collapse in the wheat
and corn belts prompted the project.
The purpose was to plant shelterbelts
on the Plains, to an extent and degree
sufficient to have some measurable

effect on the physical conditions of the
area. Through tree planting, the pro-
ject’s main purposes were to: amelio-
rate drought conditions, protect crops |
and livestock, reduce dust storms, and |
provide useful employment for
drought-stricken people. This was the
same project that some foresters,
botanists, ecologists, and other scien-
tists damned in no uncertain terms.
The 1942 Journal of Forestry quoted a
few of these comments in retrospect:
“A project which seems to me to be

(See Project on page 7)

Rocky Mountain Forest & Range Experiment Station

oforestry

National Agroforestry Center

Fall, 1995

Windbreaks in
Sustainable
Agriculture
Systems

The term “sustainable agriculture”
was introduced in the early 1980's
and has since gained wide recogni-
tion. This term is used to convey the
concepts of a system which balances
whole-farm resource management
with whole-farm productivity to meet

the needs of people. The overall level
| of achieved productivity under a sus-

tainable agriculture system is depen-
dent upon the ability to coordinate
and manage soil, water, plant, and
animal resources simultaneously,
within climatic and economic con-
straints. The type and number of
plants and animals supported by the
system are important and play signifi-
cant roles, both individually and col-
lectively in maintaining a healthy
farm environment. Basically, sustain-
able land use could be considered as
that which results in production of
goods and services for the present
generation without causing a decline
in welfare of future generations
When designing a sustainable
land-use system, decisions must be
made as to “what” is to be sustained,
and “for whom” is it to be sustained.

i insid le This Issue (See Sustainable on page 2)

Ml A New Partnership...page 2

I Windbreaks For All Seasons and Reasons...page 3

i “Working” Windbreaks Around Communities...page 4
Mf Just How Does A Windbreak Work Anyway?...page 5


(Project from page 1)

doomed to failure before it is started.”
“The plan is fantastically impossible.”
“By any fair appraisal it will be
less than a 20 percent success.”

“The whole enterprise, prominent
as it is in the public mind, bids fair to
prove a boomerang which will give
forestry a terrific setback in public
opinion.”

However, to John L. Emerson,
State Director of the Federal Forestry
Service in 1935, it was absurd that
there could have been any doubt
about the shelterbelt’s value.
“Housewives know that their clothes
dry faster in the wind,” he said, “so
why shouldn’t the same thing apply
to the soil? If we can keep the wind
off, we can save the soil by helping it
to retain mositure.”

And, Carlos G. Bates, senior silvi-
culturist for the US Forest Service in
1934, said this about the proposed
project in the November, 1934 Journal
of Forestry: “It is not an undertaking in
which slip-shod methods will suc-
ceed; it represents a challenge to the
technical skill of the profession and
will require that our coming foresters
develop a technical skill and a love for
the soil which has not been much in
evidence in the past.”

Between 1935 and 1942, more than
200 million trees and shrubs were
planted in windbreak strips on 30,000
individual farms in a patchwork pat-
tern, totalling 18,600 miles in length.
To the amazement of many, a great
number of the original shelterbelts
still remain! These windbreaks were a
major factor in taming the harsh con-
ditions that exist on the prairie and
were directly responsible for making
the Plains region what it is today...a
productive agricultural region and a
unique place to call home for millions
of people.

Representative Jed Johnson of
Oklahoma, a previous critic of the
program, had a statement printed in
the 1941 Congressional Record that said,
“The Prairie States Forestry Project
has proved to be a fully practical and
extremely beneficial aid to agriculture
in the plains country.”

It’s interesting to read through old

literature from the 1930's and 1940's.
Even then, professionals were quite
aware of the benefits of trees: wind
control, soil control, moisture reten-
tion, etc. Granted, not much research
had been done to prove these benefits.
But, the evidence was there.

What research is telling us today is
that windbreaks are effective in vari-
able climate areas like the Plains.
However, the Plains are certainly not
the only place that windbreaks can be
effectively applied. Scientists have
found that they are applicable in all
parts of the country, and for many
purposes. Of course the most tradi-
tional applications like field and farm-
stead windbreaks are still popular.
But, now variations of windbreaks are
used to help control air pollution,
deposit snow evenly across a field,
protect livestock, reduce heating and
air conditioning bills, and help keep
major roadways and parking lots
clear of snow...and the list goes on.
Furthermore, almost every state in the
union has windbreaks employed in
one form or another. Take for exam-
ple, Montana, where a windbreak is
protecting a grade school and provid-
ing an outdoor laboratory for stu-
dents. In Washington State, wind-
breaks are protecting apple orchards.
New Mexico, a low precipitation
zone, has windbreaks planted to dis-
tribute snow across agricultural fields
providing extra soil moisture in the
spring. And, of course, we can’t forget
those field windbreaks located where
it all started — in North Dakota,
South Dakota,

| (Seasons from page 3) a

for farmstead windbreaks. A survey
of the key windbreak states in the
Great Plains also showed that 60 to 80
percent need some type of renovation.
This renovation may be as simple as
removing sod from the windbreak, to
releasing the trees by thinning, to total
removal and replacement. A person
may wonder why this decline is
occurring. There are no easy answers
but a large percentage of the existing
windbreaks are over 60 years old and
reaching the end of their natural life.
Other reasons include changes in agri-
cultural production methods such as
| larger equipment leading to larger
' fields and greater use of herbicides
| which can be detrimental to the
adjoining windbreaks.
In my mind, the positive wind-

break benefits far outweigh the nega-
' tives. Windbreaks can increase “prof-
its” for clients and society, reduce
resource problems and costs, create
biodiverse habitats for humans and
wildlife, and enhance local ecosys-
tems. The “bottom line” for the agro-
forestry resource professional is to
prove to the American landusers that
windbreaks can improve their “bot-
tom line” and help society, too. With
increased interest and help by
landowners and resource profession-
als, landscapes with few trees and
shrubs can be transformed into multi-
| ple species and practices that can

enhance the farms, families, and
. future of the nation.
Appearance of an article in “Inside Agroforestry”

does not imply that the Agroforestry Center agrees,
nor endorses, the facts or opinions contained.

Nebraska, Kansas,
Oklahoma, and
Texas, the new
ones, the renovated
ones, and the ones
planted in the
1930’s, that are still
working
today...after 60

ears!

Source: Adapted from,
“Journal of Forestry,”
November, 1934 and June,
1942; and “The Myth of
Tree Planting on the Great
Plains” by Martha Jean
Williams Ferrill

IRVING WiPPLE, CONDUCTED EXPERIMENTS
fo SEE IF MONEY ACTUALLY
COULD GRoW oN TREES.

Inside Agroforestry 7



Message From the Manager

a & A
We are pleased to announce that the National
Agroforestry Center (NAC) is now a partnership of the
USDA Forest Service (FS) and the USDA Natural Resources

An important part of our role as a pioneering program
is to break barriers and build bridges.
——Bill Rietveld

Conservation Service (NRCS). The partnership expands
the Center’s outreach in agroforestry research and devel-
opment, technology transfer, and international technolo-
gy exchange. In addition, the US Agency for International
Development (USAID) will be providing initial support
for NAC’s International Technology Exchange program.
This new partnership will add six people who will be
affiliated with the Center. NRCS will assign three agro-
foresters to work full-time with the Center. One will be
located at NAC in Lincoln, one will be located at NRCS’s
new Watershed Sciences Institute in Seattle, and one will
be located at NRCS’s Grazing Land Technology Institute
in Fort Worth, Texas. In addition, NRCS will locate two
scientists at NAC, one from their Watershed Sciences
Institute, and one from their Wetlands Science Institute

A commentary on the status of agroforestry
as reported by Program Manager, Bill Rietveld

A New Partnership

(which is located in Laurel, Maryland). The sixth person
will be an International Coordinator, who will be funded
for a two-year trial basis through an agreement among
FS, NRCS, and USAID.

Interest in agroforestry is rapidly expanding, nation-
ally and internationally. Earlier this year, the Center
expanded its scope and changed its name in response to
this increasing interest. Now we have taken another step
to make the Center more responsive to the needs of agro-
forestry and its customers. The new interagency partner-
ship will work through cooperation with a national (and
international) network of agencies, universities, and
organizations to accelerate the development and applica-
tion of agroforestry technologies.

We believe this is the appropriate model for the 21st
century — develop teams and leverage limited resources
to accomplish shared goals. Agroforestry is ideally posi-
tioned for interagency cooperation and teamwork
because it is inherently cross-cutting — it crosses disci-
pline and agency boundaries. An important part of our
role as a pioneering program is to break barriers and
build bridges. We have many challenges ahead. The ball
is in our court, and we are determined to make it a suc-
cess story. We will provide updates on this and other
developing partnerships in future issues of IA.

(Sustainable from page 1)

Terms such as “production agro-
forestry” and “conservation agro-
forestry” place emphasis on “what” is
to be sustained and to some extent,
these terms also imply “for whom.”
Often times individual farmers are
more often in the business of sustain-
ing productivity, while other parts of
society may focus on sustaining envi-
ronmental benefits. An agroforestry
system should, by design, provide
both environmental and productivity
benefits; in fact, they cannot produce
one without the other in almost all
instances.

Windbreaks are a good example of
an agroforestry technology that sus-
tainably provides both production
and conservation attributes, while
producing wood products, wildlife

habitat, and increasing crop yields.
Strategically located and properly
designed, they can increase livestock
weight gain by as much as 10 percent,
while at the same time, those same
livestock will require significantly
less feed. And, during severe weather
years, tree windbreaks have increased
crop productivity by as much as 33
percent. Alfalfa yields have increased
by 12 percent and native tall grass
yields by 100 percent! Furthermore,
windbreaks can cut heating and cool-
ing costs for homes by as much as 30
percent.

Yes, windbreaks, as well as other
tree and shrub planting combinations,
have an important role to play in
today’s integrated agricultural sys-
tems. In the future, these systems will

help reduce human impact on
resources, while at the same time
provide sufficient supplies of high
quality food and fiber. Trees and
shrubs planted as windbreaks pro-
vide wind erosion control, improve
crop yield, and enhance the quality
of many wind-sensitive crops.
Finally, windbreaks add beauty to
the landscape and increase the value
of the land — all contributing to a
healthier, more pleasant sustainable
ecosystem.
Sources: “Windbreaks in Sustainable Agricultural
Systems” by Vernon C. Quam and John Gardner,
NDSU, James R. Brandle and Teresa K. Boes, UN-
L; and “Role of Agroforestry in Sustainable Land-
Use Systems” by K.N. Brooks, H.M. Gregersen,
and P.F. Ffolliott in Agroforestry and Sustainable
Systems: Symposium Proceedings, August, 1994.

2 Inside Agroforestry


Windbreaks For All Seasons and Reasons ~- ~~

by Bruce C. Wight, National Agroforester, USDA Natural Resources Conservation Service, Lincoln, Nebraska

Windbreaks have been a key agro-
forestry practice for at least the past
100 years in the United States and
continue to be probably the most
widely used agroforestry practice. As
noted elsewhere in this newsletter,
windbreaks have a long history.
Hedges were used in Europe as far
back as the English Tudors in the
1600's.

How widespread have windbreaks
been applied in the United States?
According to the 1987 USDA Natural
Resources Conservation Service
(NRCS) National Resources Inventory
(NRI), windbreaks comprise a sub-
stantial resource with windbreaks
being identified in 40 of the 50 states.
From protecting blueberries in Maine
to controlling drifting sand in
California, and from protecting grain
crops in North Dakota and Minnesota
to providing cover for wildlife in New
Mexico and the Texas panhandle,
windbreaks are providing many bene-
fits. The tree species used are as
diverse as the geographic regions
from alder protecting orchards in
New York to ponderosa pine protect-
ing livestock in Nebraska to Rocky
Mountain juniper stopping snow in
Colorado and Wyoming to ‘Tropic
Coral’ protecting flower crops in
Hawaii. A person traveling across the
country can find a use for a wind-
break in just about every state. The
region with the least number of wind-
breaks is the Southeast probably due
to the abundance of forest land.
However, even in the Southeast there
are opportunities for windbreaks such
as crop protection on sandy soils.

Windbreaks have traditionally
been used to protect soil, plants, ani-
mals, and people from adverse winds.
The term windbreak is often used
interchangeably with shelterbelt. The
NRCS considers a windbreak/shelter-
belt to be a linear planting of trees or
shrubs established for environmental
purposes. These types of tree and
shrub plantings are used to meet a
variety of purposes including reduc-

ing wind erosion, protecting growing
plants, managing snow, providing
shelter for structures and livestock,
providing wildlife habitat, providing
a tree or shrub product, providing liv-
ing screens, improving aesthetics, and
improving irrigation efficiency. The
most commonly planted windbreak
types include farmstead windbreaks
and field windbreaks.

Landowners recognize the value of
a farmstead windbreak. In fact, it is
usually the first windbreak planting
opportunity for most farmers or
ranchers. A farmstead windbreak pro-
vides a number of benefits to the
owner. Some of these benefits can be
easily translated into dollars such as a
10 to 30 percent reduction in energy
costs, increased property values,
reduced snow removal, lower feed
costs for livestock, or less physical
wind damage to buildings. Other ben-
efits are less tangible including reduc-
ing noise, improving animal health,
screening unsightly areas and
improving working conditions.

changes to adjacent fields resulting in
improved crop quality and quantity.
They can also serve as buffer strips to
help improve water quality and add
wildlife habitat. Field windbreaks
provide a variety of benefits to adjoin-
ing fields and crops including increas-
ing crop production from 6 to 44 per-
cent, reducing wind erosion from 50
to 100 percent, improving irrigation
efficiency, and managing the moisture
from snow more effectively. Field
windbreaks have changed significant-
ly from the ten row windbreaks of the
1930’s to narrow one and two row
windbreaks of today.

What does the future hold for this
“old” agroforestry practice?
Nationwide we have seen a gradual
decline in the number of windbreaks
planted and the condition of those
remaining. The NRI shows about a
four percent decline for field wind-
breaks and about a two percent loss

(See Seasons on page 7)

Table 1 — Windbreaks in the United States

Even though the term farm-

stead windbreak is used, a Windbreaks Number Acres Miles

windbreak can be used to pro- Farmstead «508,485 766,329 59,540
tect any structure ranging from Field 349,672 599,116 116,031
industrial buildings to the sub- Total 858,157 1,365,445 175,571

urban home. In a North Dakota
subdivision, windbreaks were
planted around two to three
acre lots
before the
first lot was
sold. The
subsequent
selling prices
were higher
than those in
adjoining
subdivisions
without
trees.

Field
windbreaks
can provide
wind protec-
tion and
other micro-

climatic development.

National total of farmstead and field windbreaks from
the 1987 National Resources Inventory.

In this aerial view of field and farmstead windbreaks, it's clear that this North
Dakota windbreak system was well-thought-out prior to building the housing

Inside Agroforestry 3