Inside Agroforestry

Working Trees for Livestock Brochures..................page 2

To Pasture Or To Silvopasture? ...............................page 3

Silvopasture Research Is Making ADifference.......page 4

Grazing Sheep In Forests.........................................page 7

Summer, 1998 Forest Service

Natural Resources Conservation Service

Inside This Issue

Silvopasture: Trees

and Pastures

An Ongoing Study to Understand Tree,

Forage, and Livestock Systems

(See Silvopasture on page 6)

Many landowners are accustomed to

managing their forest land or rangeland

for a single purpose. But, “silvopasture”

is the integration of trees with livestock

operations. Silvopastoral systems are

designed to produce a high-value timber

component, while at the same time providing a short-term cash flow from the

livestock operation. Silvopasture results

when forage crops are deliberately introduced into a timber production system or

when timber crops are deliberately introduced into a forage production system.

Timber and pasture in a silvopasture are

managed as a single integrated system.

Silvopastures can provide increased

economic returns while creating a sustainable production system that has many

environmental benefits. When making

tree and forage crop selections, it is

What’s in a title? Well, the title of this

article refers to a simplified definition of

“silvopasture.” But, don’t let the word

scare you off before learning about this

tree, forage, and livestock system. This

combination of three enterprises, forms a

mutually beneficial interaction that produces a practical, economic system.

Sometimes we need hard data to convince landowners to adopt new technologies. Yet, not a lot of data on silvopastures currently exist. This article describes

an ongoing study that will improve our

understanding of the key factors involved

in developing silvopasture systems. The

Louisiana Agricultural Experiment

Station is cooperating with the USDA

Natural Resources Conservation Service

(NRCS), NRCS Grazing Lands

Technology Institute (GLTI), and the

USDA National Agroforestry Center

(NAC) to evaluate the economic potential and environmental performance of sil-

(See Ongoing on page 5)

Stocker steers graze Bermuda grass under 20-year-old loblolly pine trees in Louisiana as

part of a research project evaluating the financial potential and environmental impact of silvopastoral land-use production systems.

vopastoral land-use production systems in

the southeastern U.S.

A 300-acre multifaceted silvopastoral

research study was initiated in 1998 at the

Hill Farm Research Station in Homer,

Louisiana. Loblolly pine is the major tree

species being used. It is being integrated

with different combinations of native and

introduced grasses in an effort to determine the potential of a system that allows

by Dr. Terry Clason, Forestry Research Project Leader, Hill Farm Research Station, Louisiana State

University Agricultural Center, Homer, Louisiana

“Overall, silvopastures 

can provide economic 

returns while creating 

a sustainable system 

with many 

environmental benefits.” 

Adapted from NAC Agroforestry Note - 8

“Silvopasture: An Agroforestry Practice.”

Klopfenstein et al. November, 1997
NAC Director’s Corner

2 Inside Agroforestry

A commentary on the status of agroforestry

by Center Director, Dr. Greg Ruark

Sustainable Agriculture 

and The Role of Agroforestry

Conventional wisdom has been that

livestock and trees can’t co-exist. Yet

modern agricultural practice is showing

that livestock and trees not only can coexist but, if properly managed, can provide additional income from land formerly used for a single crop. 

Coming soon is our new Working

Trees for Livestock brochure, which will

acquaint you with some of the specific

ways you and your land can benefit by

putting trees to work for your livestock.

Trees can provide livestock with protection from cold wind and blowing snow in

winter, as well as from the hot sun and

drying winds of summer. And, if commercially desirable timber or nut trees are

planted, landowners can enjoy significant

additional income from this diverse use of

their land.

Now available is our new brochure,

Working Trees for Livestock:

Silvopasture in the Southeast. This

brochure defines silvopasture systems,

discusses benefits, planning considerations, and management options as they

relate to silvopasture in the southeastern

part of the U.S.

E-mail Nancy at the Center to obtain

either of these brochures: nhammond/

rmrs_lincoln@fs.fed.us. You may want to

inquire about the many other brochures,

video’s and displays available too. You

can also call us at 402-437-5178. 

Top:

Working

Trees for

Livestock:

Silvopasture in

the Southeast;

Bottom: --

Coming

soon... Working

Trees for Livestock, which has

a national scope.

Working Trees for Livestock Brochures

ating systems that are capable of balancing the long-term social,

economic, and environmental aspects of agriculture. It is becoming increasingly important to find ways to keep agricultural lands

in production. New alternative sources of income must be developed so that producers can afford to remain on the land and the

rural communities they belong to can remain viable.

A more diversified agricultural sector means that producers

will need to select from a broad portfolio of management practices -- practices that include agroforestry technologies. In many

instances, the cost-effective incorporation of one or several agroforestry practices can be the difference between profitability and

economic loss. This is especially true for “limited resource”

farmers and ranchers who often need to find ways of generating

additional income with modest inputs and on small holdings.

Agroforestry practices such as tree/pasture systems that combine

grazing operations with timber production or the growing of

high-value specialty crops like ginseng and mushrooms under

tree shade are examples of science-based technologies that can

be readily incorporated into the existing operations of many

farms and ranches.

Increasingly, agricultural lands are being looked upon to

provide societal benefits beyond the production of food and

fiber. In this regard, the use of trees in agricultural settings typically enhances the environment in many ways, such as helping to

protect soil and water resources, providing wildlife habitat,

improving aesthetics, or linking fragments of forestland.

Agriculture provides many goods and services essential to

human livelihoods and aspirations. However, demands on agriculture continue to expand due to the rapid growth in human

population. Annually, nearly 90 million people are added to the

global population -- mostly in developing countries -- with the

U.S. population increasing by 3 million each year. For the agriculture sector to be sustainable, it must provide goods and services derived from agriculture in ways that meet the needs of the

present without compromising the ability of future generations to

meet their own needs.

Agriculture dominates many landscapes, with about 48 percent of all land in the U.S. (excluding Alaska) dedicated to agricultural purposes. However, America’s agriculture is in transition. Agricultural land in the U.S. peaked at 1.15 billion acres in

the 1950’s, but has declined to around 0.95 billion acres today.

The past 25 years have brought about a 30 percent decrease in

the number of farms and a corresponding trend toward increasing

size and greater mechanization. Pressure to develop land for

other purposes has also been escalating, resulting in nearly 3 million acres of cropland, 6 million acres of pasture, and 10 million

acres of rangeland being converted to commercial or residential

use between 1982 and 1992. In many instances, this permanent

loss to the agricultural resource base has involved some of our

most highly productive lands.

Movement toward more sustainable agriculture will require

the development of integrated whole-farm and whole-ranch oper- NAC

NAC
Inside Agroforestry 3

Pasture or Silvopasture?

For any agroforestry system to be considered a viable alternative it must provide economic or conservation benefits

consistent with a landowner’s goals. To

help landowners assess economic tradeoffs, the USDA National Agroforestry

Center has been working with the

Agricultural Research Service to adapt the

New Zealand Agroforestry Economic

Model (AEM) to United States conditions. 

This article presents the the results of

an AEM model run for a hypothetical

farm. A simplified scenario is used to

compare a forage/livestock only enterprise to a silvopasture enterprise. 

Tree growth and yield information were

provided from a model developed by the

USDA Forest Service and forage data

were provided from local site and soil

information coupled with experience. The

AEM model requires input values such as:

area in pasture, area to be planted, livestock carrying capacities, livestock values, costs, timber yields and timber values. 

The example— The AEM model was

used to analyze a 120 acre farm with 110

acres in pasture and a carrying capacity of

three acres per animal unit. This farm supports 30 cows with calves that are weaned

at 450 pounds valued at $.65 per pound.

Annual fertilizer costs, fencing costs and

management costs are estimated for the

livestock. To compare the pasture operation to a silvopasture alternative, 10 acres

are planted to loblolly pine at a spacing of

8 foot by 20 foot (272 trees per acre) each

year until 100 acres of the 110 acres

presently in pasture are planted to a silvopasture system. The rotation age for the

final crop of trees is estimated to be 50

years. The trees are thinned periodically

to remove canopy competition for the

grass. The trees are removed and sold for

pulp, chip and saw, or sawtimber as

appropriate. Final crop trees are pruned to

a four inch diameter limit or 30 percent of

the crown, which ever is less. These trees

are pruned twice during the rotation to

produce quality sawlogs from open grown

trees. Prescribed burning is conducted at

four year intervals beginning at the age of

10 years. A fertility program is practiced

to maintain forage production. 

The AEM analysis can be displayed in

both graphs and tables. Prices and costs

used in evaluating actual situations are

by James L. Robinson, NRCS Agroforester, National Agroforestry Center, Fort Worth, Texas and Dr. Catalino Blanche, Research Forester, USDA ARS, Booneville,

Arkansas

either those supplied by the landowner,

and/or those assessed as reflecting the

current market situation. It must be recognized that costs, prices and technology

will change in the future and this analysis

can only describe the present situation

and provide a benchmark against which

to note future changes. 

Chart 1 shows the estimated net cash

flow for the farm. Line (L) depicts a uniform annual return from the livestock

only enterprise, whereas line (A) shows

the variable annual return from the silvopasture enterprise (livestock and trees).

The income spikes are due to thinning

and the troughs to planting and management costs. The area (C) represents the

cost of establishing the agroforestry system, including the income foregone due

to livestock displacement by trees, and is

the difference in income between that

earned with the livestock only enterprise

(line L) and the silvopasture (livestock

and trees) enterprise (line A). The area (I)

represents the additional income realized

by implementing the agroforestry system

and is the difference between the income

earned through the silvopasture system

(line A) and the income earned with the

livestock only enterprise (line L). As with

any system, there is an initial cost of

(See Pasture on page 7)

This silvopasture system in Louisiana supports a cow/calf operation. If implemented and

managed properly, silvopasture systems can be a viable alternative to a landowner, providing them with economic and/or conservation benefits.

Chart 1: Net farm cash flow for a hypothetical farm.
Spotlight On Success Florida

4 Inside Agroforestry

Making A Difference In Silvopasture Research

the University of Florida, School of Forest Resources and

Conservation until he retired.

Over the course of his career, Lewis was involved in numerous research projects including a 20-year study on tree density

and tame pasture species in silvopastoral systems. He studied

multiple combinations involving native forages and tree planting

configurations, native forage and site preparation for planting

pines, and use by both domestic livestock and wildlife. 

Some research involved achieving higher native forage yields

by planting trees in close configurations (usually double rows)

instead of the traditional evenly-spaced plantings. Applying this

concept to tame pastures, he pioneered what appeared to be a

unique “alley cropping-grazing” system.

According to Lewis, his research did not initially receive a

lot of attention in the

United States.

However, it was more

readily accepted overseas, usually in the

tropical and semi-tropical areas of developing nations. 

Lewis believes that

the major barrier to

acceptance in the U.S.

is "the fear of the

unknown." 

"People are afraid

that they don't have

enough expertise in

the new discipline,"

Lewis said. "Cattle

producers do not

want to become

foresters, and forest managers do not wish to learn about

livestock production and the interactions of mixing these

disciplines." 

Lewis looks upon his career with the Forest Service as

rewarding. However, in retirement, he was fortunate

enough to find a second rewarding career. Lewis currently works at Chipola Junior College in Florida on a federal grant called “Tech Prep”, designed to better prepare

high school students for employment and advanced education. At the same time he also works with past Forest

Service colleagues in publishing his research data on forest grazing and long-term ecological studies.

Although his current career is quite different than that

with the Forest Service, he still goes home from work in

the evenings feeling that he has made a difference.

Clifford Lewis is a man who truly made a difference in

the field of agroforestry through his innovative silvopasture research.

After a long, distinguished career with the USDA Forest

Service, Cliff Lewis continues to work on disseminating his previous silvopasture research findings. Although this 1989 retiree

no longer works in the natural resources field, he still puts his life's

work on paper, adding to a collection of over 75 publications.

Cliff Lewis was one of the first U.S. researchers in the area of

silvopasture and his work in cooperation with other forest grazing specialists has made the science of silvopasture in the

Southeast what it is today.

Lewis began his career shortly after finishing his Master of

Science degree in range management from Utah State University.

This New Mexico native was offered a grazing research position

at Ft. Myers, Fla., with the Southeastern Forest Experiment

Station in 1960. This was his introduction to forest grazing which

became the focus of his career. His research centered on grazing

intensity, range improvement using rock phosphate, and fire

ecology.

After six years, Lewis was transferred to the University of

Georgia, Coastal Plains Experiment Station in Tifton, Ga. It was

here that he became involved in some of the earliest research on

planting pines in improved pastures. In the 1980's this activity

became known as the agroforestry practice, silvopasture.

Forest grazing by domestic livestock actually began in Florida

in the early 1500’s with the introduction of Spanish/Portuguese

cattle.

“Forest grazing research was still new in 1960 when I first

started with the Forest Service," Lewis said. "In 1955, the Forest

Service began research in Florida while another research effort

was started in Tifton in 1947. At this time, there was little interest by the state universities in forest grazing."

In 1972, Lewis returned to Florida to begin studies on grazing

and wildlife in Marianna. He remained in Florida’s panhandle

until 1981 when he was assigned to do cooperative research with

Double-row Slash pine configuration planted on natural forage example. This

research plot in Florida was initiated by Cliff Lewis and his associates.

Cattle graze on Bahia grass among Slash

pine on a plot of private land in southcentral Georgia.

by Clover Shelton, Technology Transfer Assistant, NAC, Lincoln, Nebraska

NAC
Inside Agroforestry 5

for annual timber harvests while maintaining a livestock/forage program on the

same acres. Researchers will also be

checking the effect of the competition

between the trees and grasses on their

productivity.

Tree growth plays a central role in the

success or failure of silvopasture because

tree-to-tree competition influences both

timber and forage production. Reducing

the number of trees, altering their spatial

arrangement, or manipulating the amount

of crown cover all influence the competition of the tree crop with forage species

and the ultimate environmental and economic outcome.

The study incorporates six different

tree-age classes, five types of arrangements, and an array of pruning options.

Trees were planted at densities as sparse

as 220 trees per acre and as dense as 680

trees per acre. The trees were arranged in

one, two, or three-row sets on 8, 12, 16,

24, and 32 foot centers. Intermediate harvests will be made at 10 and 15 years to

reduce tree density. Final harvests will be

made at 25, 35, and 45 years. Mechanical

and chemical pruning methods will be

used to manipulate the amount of crown

cover (shade). The pruning practices will

be applied at tree ages of 4, 7, and 10

years. Tree growth and log quality will be

evaluated in reponse to annual nitrogen

fertilization, tree spacing density, and naturally occurring damage such as hail or ice.

It’s important to examine grass production at the same time as tree production. Of major importance is assessing the

influence of timber management practices

on the performance of perennial warmseason grasses. Production of warm season

grasses (bahiagrass, common bermudagrass, and coastal bermudagrass) and cool

season forages (ryegrass and subterranean

clover) will be evaluated under tree

canopy densities of 50, 75, and 150 

trees per acre at various tree ages.

Influence of different fertilizers and application rates on the grasses and forages

within the different research scenarios

will also be assessed. The potential for

alley crop hay production will also be

investigated.

In areas where beef cattle will be utilizing the forages, electric fencing and

portable watering systems will be used to

control grazing patterns and pressure. The

fencing will also be used to control excessive grazing pressure commonly associated with riparian zones along existing

streams and ponds. 

A beef cattle production cycle includes

a gestation phase, a cow/calf phase, and

stocker phase. In order to maintain animal

ownership through the production cycle, a

silvopastoral land base must contain six

acres for every animal in the stocker

phase of the cycle. The study area will be

managed to sustain nine months of grazing by overseeding a warm-season perennial forage with ryegrass and/or subterranean clover. Designated alley crop

areas will be managed to produce Coastal

bermudagrass hay for winter feed supplementation. Subsequently, cattle will be

introduced and managed to produce 50

yearling stockers per year. In addition to

beef cattle production, the study area will

be used to evaluate the potential to background dairy heifers in silvopastoral situations.

Silvopastures are neither timber nor

forage production systems. Instead, they

are biologically responsive land management systems that enhance long-term

value of the timber component, and sustain the short-term cash flow value of the

livestock component. Periodic timber harvests and annual forage production fluctuations limit the financial potential of individual silvopastures. However, a commercial land-use production system that

combines several individual silvopastures

could be a financially successful and

environmentally sensitive option. 

Management practices applied on a

landscape basis would sustain annual timber and livestock production at marketable levels. Distributing production

costs between the timber and livestock

components would provide affordable,

reliable, and flexible sources of raw material for primary and secondary manufacturing facilities. Since management intensity would be reduced across the landscape, environmental quality would be

enhanced by increasing nutrient cycling,

minimizing pesticide and fertilizer usage,

restricting mechanical tillage practices,

and protecting riparian zones.

Portions of the research results will 

be available in 1999. For more information contact, Terry Clason at 318-927-

2578.

(Ongoing from page 1)

First Call for Papers and

Posters for Sixth

Agroforestry Conference

in 1999

Sustainable Land-Use

Management 

for the 21st Century

The sixth conference on 

agroforestry in North America will

be held June 12-16, 1999 at the

Arlington Resort Hotel in Hot

Springs, Arkansas

Anyone involved in research, technology development, or implementation

of agroforestry practices in North

America or other temperate regions is

invited to submit titles for proposed

presentations to conference organizers. Submissions should include title,

agroforestry category (alley cropping,

forest farming, riparian zones, silvopasture, windbreaks, or general) and

subject area (management, biology,

economics, environmental, societal,

policy, modeling or general).

Submit title information by 

October 1, 1998 to:

Terry Clason

Hill Farm Research Station

Route 1, Box 10 

Homer, Louisiana 71040-9604. 

E-mail: tclason@agctr.lsu.edu.

For more information about the

conference program, contact:

Dr. Catalino Blanche

Dale Bumpers Small Farms 

Research Center

6883 South State Hwy 23

Booneville, Arkansas 72927-9214.

E-mail: cblanche@yell.com

Co-Hosts of Conference

Dale Bumpers Small Farms Research

Center and Hill Farm Research

Station.

NAC
6 Inside Agroforestry

important to consider potential markets,

soil type, climatic conditions, and species

compatibility. 

The timber component should be: 

marketable, high quality, fast growing, 

deep-rooted, drought tolerant, and 

capable of providing the desired products

and environmental services. On marginally productive lands, conifers are well-suited for silvopastures because they can

adapt to diverse growing sites, respond

rapidly to intensive management, and permit more light to reach the forest floor.

Select and use trees and planting/harvesting patterns that are suitable for the site,

compatible with planned silvopastoral

practices, and provide desired economic

and environmental returns.

The forage component should be a

perennial crop that is: suitable for livestock grazing, compatible with the site

(soil, temperature, precipitation), productive under partial shade and moisture

stress, responsive to intensive management, and tolerant of heavy utilization. 

Potential livestock choices include cattle, sheep, goats, and horses. In many

instances it is possible to incorporate

turkeys, chickens, ostriches, emu, or rhea

along with the grazing livestock, or game

animals such as bison, deer, elk, caribou,

etc. The selected livestock system must be

compatible with tree, forage, environment, and land use regulations. In general,

browsing animals such as sheep, goats, or

deer are more likely to eat trees; whereas,

large grazing animals such as cattle or elk

are more likely to step on young trees.

Younger livestock are more prone to damage trees than are older, more experienced

animals. Livestock are more likely to

impact hardwood trees than conifers.

Design and Establishment:

Silvopastures can be established on any

land capable of simultaneously supporting

tree and forage growth. However, silvopastoral systems can require a relatively large land base to sustain timber and

livestock production continuity.

Appropriate establishment methods

depend on: woodland/forest type (e.g.,

site conditions, and tree species, age, pattern, and spacing) or existing pasture situation and landowner objectives (e.g., timber products, environmental benefits,

wildlife, etc.). Appropriate grazing systems depend on climate, terrain, tree

species, tree age, other vegetation, kind

of livestock, labor requirements, and

extent of fencing, water supplies, and

supplementary equipment.

Tree spatial arrangement is an important factor for silvopasture success. Trees

can be evenly distributed over the area to

optimize growing space and light for both

trees and forage. Alternatively, grouping

trees into rows or clusters concentrates

their shade and root effects while providing open spaces for pasture production.

Trees are typically pruned to increase

light penetration and develop high-quality

sawlogs. Silvopasture systems of varying

ages can be managed to achieve landscape-scale objectives.

Management: Livestock grazing

should be closely managed. A successful

silvopasture requires understanding forage growth characteristics and managing

the timing and duration of grazing to

avoid browsing of young tree seedlings or

elongating shoots. Livestock should be

excluded from tree plantings during vulnerable periods. Similar approaches can

minimize damage by trampling or rubbing. Improper management of silvopastures can reduce the number of desirable

woody and herbaceous plants by overgrazing and soil compaction. 

Economic: Integrating trees, forage,

and livestock creates a land management

system that can produce marketable products while at the same time maintain

long-term productivity. Economic risk is

reduced because the system produces

multiple products, most of which have an

established market. Production costs are

reduced and marketing flexibility is

enhanced by distributing management

costs between timber and livestock components. Comprehensive land utilization

in silvopastoral systems provides a relatively constant income from livestock

sale and selective sale of trees and timber

products. Well-managed forage production provides improved nutrition for livestock growth and production. 

Woodland and Forage: Grazing can

control grass competition for moisture,

nutrients, and sunlight, thereby enhancing

tree growth. Well managed grazing provides economical control of weeds and

brush without herbicides, maintains fire

breaks, and reduces habitat for gnawing

rodents. Fertilizer applied for forage is

also used by trees. In addition, livestock

manure recycles nutrients to trees and forage. 

Livestock: Some forage species tend to

be lower in fiber and more digestible

when grown in a tree-protected environment. Trees that provide shade or wind

protection can have a climate-stabilizing

effect to reduce heat stress and windchill

of livestock. Protection from trees can cut

the direct cold effect by 50% or more and

reduce wind velocity by as much as 70%.

Livestock require less feed energy, so

their performance is improved and mortality is reduced.

Environment and Aesthetics:

Silvopastures can increase wildlife diversity, and improve water quality. The forage protects the soil from water and wind

erosion, while adding organic matter to

improve soil properties. Silvopastures

provide an attractive landscape with an

aesthetically pleasing “park-like” setting.

In contrast to concentrated livestock operations, silvopastoral systems are less likely to raise environmental concerns related

to water quality, odors, dust, noise, disease problems, and animal treatment.

Agroforestry Notes 8 and 9 provide

more details.

(Silvopasture from page 1)

Exploring Agroforestry

Opportunities in the

South

October 19-21, 1998

Huntsville, Alabama

Presentations by researchers and 

specialists will explore different 

agroforestry systems and 

opportunities for agroforestry 

in the south. 

For more information, contact: 

Dr. George Brown, Alabama A&M

University • Phone: 256-858-4189

Sponsored by: Alabama A&M

University • USDA NRCS • USDA

Forest Service

NAC
Inside Agroforestry 7

People have been grazing livestock in

the forest for centuries. But, producing

both livestock and trees under a symbiotic relationship is a much newer idea.

Researchers in the foothills of western

Oregon have been studying sheep and

forests for some time now. And, overall,

they’ve found that the two really can coexist. 

For the past 30 years, agroforesters in

New Zealand have been successfully producing sheep and timber crops. Research

in Oregon is building upon efforts in New

Zealand. An initial Oregon project conducted during the late 1970’s showed a

38 percent increase in income by switching from conventional pasture systems to

agroforestry. However, early successes

also led to a lot of questions that had no

research base. And, this is where Rick

Fletcher and Garry Stephensen, Oregon

State University Extension agents, and

business sponsor Rising Oak Ranch,

owned and managed by Jim and Lou

Moroe, come in. In 1990 this group,

along with several other sponsors, established test plots evaluating three tree

species, two planting designs, and two

establishment schemes against traditional

Grazing Sheep in Forests

(Pasture from page 3)

forest-only and pasture-only controls. 

The researchers have begun to evaluate

their technical results. They also have

preliminary estimates on the costs of

establishing an agroforest and on browse

damage as well as data on seedling mortality and forage production.

To date, researchers have learned several primary lessons. These include: 

Establish the pasture first. In New

Zealand, they have a concept of establishing trees on pasture. We believe that this

should also be the preferred sequence for

landowners in western Oregon. This

allows the farmer to do soil preparation,

and have ample room for equipment

needed for pasture establishment. It is

then quite a simple operation to spray out

small strips or spots to use for tree planting.

Manage your herd carefully. There is

no substitute for vigilance on the part of

the shepherd. At every age up to eight

years, the livestock were capable of doing

damage to the trees if left unattended for

long periods of time. The younger the

trees, the more frequent the monitoring

needed. For very young trees, the flock

should be monitored every couple of

hours. For trees above browse height,

they should be checked daily.

Weed out tree eaters from your

herd. In the case of sheep, it was very

apparent that tendency to browse a

conifer tree was linked to certain animals

and their offspring. Certain ewes did all

the damage, and they passed this characteristic on to their lambs at an early age.

These animals should be identified early

and shipped to a pasture-only farm.

Matching tree species to site is critical. The biggest variation in growth and

survival is linked to soil-tree species

interactions. Agroforesters must pay close

attention to the soil requirements of the

trees they are planting and the soil characteristics at the planting site.

Researchers plan to include a commercial thinning to remove lower quality

trees, leaving approximately 100 pruned

trees per acre. Forage production will

continue to be monitored annually. Tree

growth will be assessed at year 10 and

again at year 20. At year 20 an economic

assessment and project summary is

expected.

Adapted from “Agroforestry for Linn

County Foothills,” by Rick Fletcher, Gary

Stephenson, and Brad Withrow-Robinson.

establishment, but once in place net

income is increased and sustained

through time. This analysis shows that the

income from the silvopasture system over

the 50 year rotation is significantly

greater than that of the pasture system

alone. The age at which net income from

the silvopasture system begins to exceed

that of the pasture-only system is 16 in

this example, but would vary depending

on when the first commercial thinning

could be scheduled. The ideal scenario

would be an implementation program that

would remove the spike incomes and provide a steady state with a constant schedule of planting and harvesting. 

Chart 2 reflects the cash flow that

would be achieved under this ideal scenario. This means a gradual decrease in

income (area C) during the establishment

period while a relatively constant cashflow (line A) will be maintained once

harvesting begins. AEM analysis for the

hypothetical farm described here shows

that a planting and harvesting scheme of

approximately 2.5 acres per year would

be required to achieve the steady state on

this operation. However, this scenario is

not practical because 2.5 acres is too

small to attract contract harvesting of the

trees. AEM also shows, in this example,

that the total farm livestock units

decreased from a carrying capacity of 30

animal units for the pasture only scenario

to 26 animal units with the implementation of the silvopasture system even

though net income (I) was increased.

Other analysis that AEM will display are:

• Wood production

• Labor requirements

• Allowable cut

• Forage production

• Planting acres by year

• Tables of all farm accounts and costs 

• Net Present Values chosen discount 

rates.

Is silvopasture the most economical

system for you? The Agroforestry

Economic Model under development is a

tool that will help landowners make the

best informed decision possible. ARS,

NRCS and Forest Service professionals

are planning to deliver AEM training, for

conservation professionals, beginning in

June 1999. 

Chart 2: Cash flow that would be achieved

under an ideal scenario.

NAC

NAC
Upcoming Events From the Editor

October 4-7, 1998

North American Conference on 

Enterprise Development Through 

Agroforestry: Farming the Forest & 

Agroforest for Specialty Products, 

Minneapolis, MN. Contact, Scott 

Josiah, 612-624-7418.

October 19-21, 1998

Exploring Agroforestry Opportunities 

in the South, Huntsville, AL. Contact 

Dr. George Brown, 256-858-4189.

Inside Agroforestry is published quarterly by the

USDA National Agroforestry Center. Phone: 402-

437-5178; Fax: 402-437-5712.

Greg Ruark, Center Director, ext. 27

Michele Schoeneberger, Research Program 

Leader and Soil Scientist, ext. 21

Jerry Bratton, FS Lead Agroforester, ext. 24

Bruce Wight, NRCS Lead Agroforester, ext. 36

Kim Isaacson, IA Editor, Technology Transfer 

Specialist, ext. 13

Clover Shelton, Technology Transfer Assistant, 

ext. 14

Jim Robinson, NRCS Agroforester located at Fort 

Worth, TX; phone: 817-509-3215

Gary Kuhn, NRCS Agroforester located at 

Seattle, WA; phone: 206-616-7166

Web Site: www.unl.edu/nac

Mission

The National Agroforestry Center (NAC) is a partnership of the USDA Forest Service,

Rocky Mountain Research Station and State & Private Forestry and the USDA Natural

Resources Conservation Service.The Center’s purpose is to accelerate the development and

application of agroforestry technologies to attain more economically, environmentally, and

socially sustainable land-use systems. To accomplish its mission, the Center interacts with a

national network of partners and cooperators to conduct research, develop technologies and

tools, establish demonstrations, and provide useful information to natural resource professionals.

USDA policy prohibits discrimination because of race, color, national origin, sex, age, religion, or handicapping condition.

Any person who believes he or she has been discriminated against in any USDA-related activity should immediately contact the Secretary of Agriculture, Washington, DC 20250.

June 12-16, 1999

Sixth Conference on Agroforestry in 

North America -- Sustainable LandUse Management for the 21st Century,

Hot Springs, AR. Contact, Dr. Catalino

A. Blanche, 501-675-3834.

NAC has literature available to provide

you with more information on agroforestry. And, we also have brochures,

displays, and videos for you to use as

tools to educate landowners. If you’re

interested in any of this material, e-mail

Nancy at nhammond/rmrs_lincoln@

fs.fed.us. Or, call her at the Center at 402-

437-5178 Ext. 11. Visit our web site at

www.unl.edu/nac. 

Opinions expressed in Inside Agroforestry are those of the author and do not necessarily represent the policy of the USDA Forest Service and the USDA Natural Resources Conservation Service.