11. Agroforestry Options for Woodland Owners

Diomy S. Zamora, Extension Educator, University of Minnesota

Gary Wyatt, Extension Educator, University of Minnesota

The practice of integrating the management of trees, crops, and livestock on the same piece of land is called agroforestry. Agroforestry is the intentional integration or combination of trees, shrubs, crops and livestock in ways that increase the overall benefits (economic) of the system to the landowner while providing important environmental benefits. Agroforestry is intensive land-use management that optimizes the benefits from biophysical interactions created when trees or shrubs are deliberately combined with crops or livestock. Multispecies and multi-strata systems create benefits that are greater than would be possible with the same species in a monoculture configuration.

Agroforestry can be thought of as working trees with specific jobs that help people and natural resources. Agroforestry is a unique land management approach that provides opportunities to achieve landowner goals of productivity and profitability with environmental stewardship that result in healthy, sustainable agricultural systems that can be passed on to future generations.

Key Traits of Agroforestry Practices

Agroforestry involves intensive management of the interactions of the components (trees, crops, and livestock) as an integrated agroecosystem. These four key characteristics – intentional, intensive, interactive, and integrated agroecosystems – are the essence of agroforestry and are what distinguish it from other farming or forestry practices. To be called agroforestry, a land use practice must satisfy all of the following four criteria:

1. Intentional: Combinations of trees, crops and/or animals are intentionally designed and managed as a whole unit, rather than as individual elements which may occur in close proximity but are managed separately.
2. Integrated: Components are structurally and functionally combined into a single, integrated management unit tailored to meet the objectives of the landowner. Integration may be horizontal or vertical, and above-or below ground. Integration of multiple crops utilizes more of the productive capacity of the land and helps to balance economic production with resource conservation.
3. Intensive: Agroforestry practices are intensively managed to maintain their productive and protective functions, and often involve annual operations such as cultivation, fertilization, irrigation, pruning, and thinning.
4. Interactive: Agroforestry actively manipulates and utilizes the biophysical interactions among components to yield multiple harvestable products, while concurrently providing numerous conservation and ecological benefits.

The Five Major Agroforestry Practices Suitable for your Farm or Woodland

Agroforestry can be tailored to work in almost any resource situation. There are five major agroforestry practices including: 1) silvopasture, 2) windbreaks, 3) alley cropping, 4) riparian forest buffers, and 5) forest farming.

Silvopasture

Silvopasture is a practice where trees, livestock, and forages are intentionally managed together. Well managed silvopastures often include planted or native pasture grasses, fertilization, and rotational grazing systems with short grazing periods. This maximizes vegetative plant growth, health and harvest. Silvopastures are intensively managed to optimize the production of forest products and forages. Haying, fertilization, tree pruning and trimming and other cultural practices should be planned in advance to compliment all operations. Silvopasture can be established in two ways:

1. Establish forages in the woods: By establishing select forages in an intensively manipulated woodland environment, the area can be jointly managed for grazing and timber production. The keys to successful silvopasture will be forage production and rotational grazing. Factors influencing this system include:
   • Providing the light necessary for forage growth and response.
   • Adjusting soil fertility to enhance forage development.
   • Adjusting light by reducing tree density and managing tree spacing.
   • Managing animal density per acre, timing of grazing and rotational length to allow for adequate tree growth and reproduction.
   • Planting inter-seeding shade tolerant grasses, legumes and forbs to enhance the production and yield of the forage.
2. Establish trees into existing pasture: The right choice or selection of tree crop (often matched to soils) allows you to carry on a profitable livestock operation while creating a long-term investment in timber and/or forest products. Young trees allow plenty of light for forage production. Additionally, as the tree component develops, shade and wind protection will enhance livestock performance. Young trees will need to be protected from grazing livestock. Fencing (e.g., electric fencing is common) can be constructed to protect trees in rows or individual trees.

There are several benefits to implementing a silvopasture system:

• Cooler summer environment for livestock for improved animal productivity.
• High value timber products resulting from pruning and management of tree density.
• Shaded, cool season forage plants can be more nutritious for livestock.
• Diversification of income streams spreads out market risk and increases income opportunities.
• Greater plant nutrient uptake efficiencies – the deep tree roots coupled with pasture plant roots acquire nutrients from greater range of soil depths.
• Pasture grasses and legumes seeded in the area help reduce erosion, provide high quality forage and decrease unwanted trees and brush.
• Integrated trees and livestock diversifies the farm enterprise.
• Enhances wildlife habitat.

Economic and environmental considerations should be explored before starting a silvopasture system. Land use zoning, tax regulations, plant and tree selection, and potential markets are important points in the design of silvopasture. The timber in the pasture should be marketable, fast growing and high quality, and should eventually provide an income for the landowner. The forage chosen should be palatable, site specific, tolerant to the amount of sunlight it will receive, and responsive to intensive management. Consult your local forester and/or grazing specialist to get assistance in establishing silvopasture including selection of sites, trees, and forage. A good resource for rotational grazing and establishing an effective fence, gate, and water system is the Pastures for Profit document available from the Natural Resources Conservation Service.

Windbreaks

Windbreaks are plantings of single or multiple rows of trees, shrubs or grasses that protect crops, livestock, and wildlife from wind’s harmful consequences. It also provides additional source of income. Historically, windbreaks were planted for a single purpose such as protecting homes from cold winds or soil from erosion winds. Today, windbreaks are being employed to address numerous other problems and provide a variety of other benefits. When properly designed, located and managed, windbreaks can produce marketable products, reduce energy costs, sequester carbon, produce oxygen, and improve crop and livestock health and production. There are several benefits of windbreaks including:

• Reduced soil erosion: Planting windbreaks around open fields can significantly reduce erosion. The barrier effects of windbreaks can reduce the speed of winds that cause erosion.
• Reduced energy costs around farmsteads: Planting windbreaks around rural homes and farmsteads can reduce energy costs from heating and cooling.
• Provide odor mitigation around livestock operations: Windbreaks can intercept and disperse odors before they accumulate and become a nuisance downwind of a livestock operation.
• Reduced wind stress on crops and improve crop microclimate and yield: Wind can physically damage plants through abrasion and leaf tearing, which can hinder plant growth. By reducing wind speed, windbreaks can reduce this damage to downwind crops. Reduced wind speed in the lee of a windbreak can also increase humidity as well as air and soil temperatures for crops. It is recommended to plant a vegetation buffer between trees and crops to enhance crop productivity.
• Protect livestock from wind stress: Like crops, microclimate conditions for livestock can also be improved by windbreaks in feedlots and pastures. Livestock tend to prefer grazing in areas sheltered by windbreaks over open areas during cold and windy conditions.
• Snow is managed around roads and farmsteads: Living snow fences – windbreaks planted next to roads to trap upwind blowing snow – are a cost-effective solution to reducing snow removal costs and preventing accidents from snow drifting and blowing. Wind and snow can also be modified within the farmstead to protect feedlot, farm yards, and high traffic areas.
• Snow is managed on croplands: Moisture from snow can be an important water resource for crop production in northern, semiarid areas. Windbreaks planted to trap snow on fields can add to soil moisture in the spring.
• Provide other ecosystem services, such as wildlife habitat, and recreational opportunities: Windbreaks can often provide structural habitat for birds and insects, some of which may be valuable for the control of crop pests. They can also attract game species such as pheasants and quail and improve hunting opportunities.
• Provide timber, biomass, fruit, and/or floral products: Windbreaks planted with valuable timber species can be harvested in the future and provide the farmer with additional income. Wood from the windbreaks can also be harvested for building material or firewood. Windbreaks can also provide economic outputs in the form of fruits and nuts or floral products.

There are several key establishment and design considerations for windbreaks:

• Vegetation: The final selection of the tree and shrub species to plant will vary at each facility and farm site and should be based on: soil type, natural drainage, common wind conditions, annual precipitation, natural range of each woody species and site needs.
• Density: The more solid or dense a windbreak, the greater the wind speed reduction. However, less dense plantings provide protection over a greater distance. Density can be managed by the plant species chosen, the spacing within and between rows, and the number of rows.
• Orientation: Windbreaks are most effective when oriented at right angles to troublesome winds. To allow for changes in wind direction, windbreaks are often planted in multiple directions – in an L shape or an arc. Avoid placement that may interfere with overhead lines, buried cable, crop tile lines, and road visibility.
• Height and length: The height determines how far downwind the protection will reach. For adequate protection, the windbreak must be taller than what is being protected. The length determines the total area that will be protected. As a rule of thumb, windbreaks typically reduce downwind wind speed for a length of 10H to 30H. For example, a windbreak with a height of 10 feet will reduce downwind wind speed for a distance of 100 to 300 feet. Windbreaks will also offer some distance of reduced upwind wind speed; this typically extends to a distance of 2H to 5H upwind. Since wind flows around the ends of a windbreak, the length of the windbreak should be at least ten times as long as its height (10H) for maximum wind reduction.
• Management: Proper care of windbreaks is critical to its long-term function. Windbreaks need regular monitoring and maintenance from the day they are planted. Practices such as weed control, protection from livestock and wildlife damage, corrective pruning, replanting, insect and disease control, and supplemental watering maybe needed on a continuing or periodic basis.

Alley Cropping

Alley cropping is an agroforestry practice where agricultural or horticultural crops are grown in the alleyways between widely spaced rows of woody plants. By combining annual and perennial crops that yield multiple products and profits at different times, a landowner can use available space, time, and resources effectively.

There are unlimited planting combinations for alley cropping systems. Common examples in the Midwest include wheat, corn, soybean or hay planted in between rows of black walnut or hybrid poplars. Non-commodity or value-added crops may be incorporated for extra income, including sunflowers or medicinal herbs planted in rows of nut or fruit trees alternated with nursery stock trees or hazelnuts.

Alley cropping can be used for other purposes such as short-rotation woody crops of fast growing woody species that are combined with forage or row crops to produce biomass for energy and fodder. Plantings to enhance wildlife and pollinator habitat also can be designed using appropriate species.

Innovative landowners have developed a wide variety of other alley cropping designs and crop mixtures. For example, various combinations of chestnuts, hazelnuts, decorative willows and ornamental foliage plants to produce greenery have been grown for farmers’ markets and other niche markets.

There are several benefits of alley cropping including:

• Diversification of income: Landowners who diversify by growing more than one type of crop are in a better position to tolerate market fluctuations or crop failures. Since timber, nut, or fruit-bearing trees may take a number of years to mature, the space between rows can be used to grow other crops that require more sun during the early stages of tree establishment. In addition, the alleyway crops and trees mature at the different times, which provides periodic income during the year, rather than relying on a single harvest period.
• Improved soil health: Alley cropping is a good option for areas prone to erosion or in a degraded shape, especially when tree or shrub rows are planted along contours. Woody roots in alley cropping systems help reduce soil erosion, increase water infiltration, add organic carbon to the soil, recycle and add nutrients to the soil, and improve nutrient retention.
• Improved crop health: Tree and shrub canopies in an alley cropping system protect the inter-crop against wind damage and insect pests, moderate air and soil temperature extremes, and reduce moisture loss from the soil. Reducing wind effects also aids in pollination activities by beneficial insects thus increasing yields of some crops.
• Improved water quality: The tree roots in alley cropping systems minimize nitrogen leaching hence improving water quality. Nitrogen leached beyond the cropping root zone is often captured by the deeper tree root systems.

Before beginning an alley cropping system, a landowner must take into account a few key establishment and design considerations. These include 1) the amount of rainfall, 2) the compatibility of trees and shrubs with crops to make sure competition for water, nutrients, and light is minimized, 3) the spacing between and within rows, 4) the sun’s direction, and 5) any maintenance requirements and available equipment.

Alley cropping systems can be designed and established depending on the landowner objectives. There are several ways of establishing alley cropping systems:

• Convert existing orchard into an alley cropping system by integrating agronomic or forage crops. Thinning of the orchard may be employed to allow for the establishment of alley cropping systems.
• Cultivate forage crops between rows of trees or shrubs which can be used for cattle and livestock.
• Alternate perennial crops such as medicinal plants or Christmas trees within tall field crops such as corn.
• Consult your local forester, agronomist, or Soil and Water Conservation District for assistance in identifying suitable tree-crop combinations.

Riparian Forest Buffers

Riparian forest buffers are strips or multiple-row plantings of trees, shrubs, grasses and forbs along rivers, streams, lakes and wetlands. They are planted along water bodies to prevent pollutants from agricultural runoff to enter the water. This practice can be designed not only to enhance wildlife habitat but to produce income while accomplishing conservation goals.

Riparian buffers are best suited for landscapes that were originally forested or wooded, as opposed to prairie landscapes. The width, layout and plant composition of forested riparian buffers vary depending on floodplain characteristics, landowner goals, and conservation program requirements.

There are several environmental benefits of riparian forest buffers, including:

• Protection of water quality by reducing the amount of sediment, excess nutrients, pesticides and other pollutants entering streams, ditches, lakes, wetlands and other surface water.
• Reduction of excess nutrients and other chemicals in shallow groundwater flows.
• Slowing of flood waters and reduction of stream water volume.
• Stabilization of stream banks and shorelines through root absorption.
• Provides shade, shelter, and food for fish and other aquatic species. Shade is especially important for cold-water species.
• Provides habitat and travel corridors for diverse plants and animals especially birds, reptiles and others that require water with adjacent woods.

In addition to their environmental benefits, there are many practical benefits of riparian forest buffers, including:

• Provides woodland recreational opportunities such as fishing, hunting, birding, hiking, and camping.
• Provides opportunities for additional income from timber, firewood, and specialty woodland products such as nuts, berries, mushrooms, medicinal plants and decorative floral materials (e.g., flowers, boughs, stems, and vines).
• Creates a highly visible sign of good stewardship, especially along recreational streams.
• Straightens irregular fields, keeps farm machinery away from steep banks, and avoids the need to plant end-rows where crop yields are often lower due to soil compaction.
• Provides a barrier against nearby dust, odor, noise or light pollution.
• Adds scenic beauty and may increase property values.
• Provides habitat for important pollinator species that many crops rely on.

Before establishing riparian forest buffers, a landowner must take into account a few key establishment and design considerations. The vegetation you select should match your goals (Table 11-1) and can include a variety of trees, shrubs, and native grasses (Table 11-2). The most common design for a riparian buffer includes three zones: an unmanaged woody zone nearest the stream which is followed by a woody zone that can be managed for income and is bordered by a zone of grasses that may include forbs (Figure 11-1). Riparian forest buffers are at least 35 feet wide but range up to 100 feet or wider for water quality purposes and up to 600 feet wide for wildlife habitat purposes.

A variety of resources are available to you. Contact your local Soil and Water Conservation District or Natural Resources Conservation Service for assistance in designing riparian buffers suitable for your goals.

Forest Farming

Forest farming is cultivating high value specialty crops under the protection of a forest canopy that has been modified to provide the optimal level of shade necessary for the optimum growth of selected crops. In other words, it is the intentional and sustainable cultivation of marketable non-timber forest products (NTFPs) in woodlands with suitable shade and site conditions. NTFPs include a broad range of goods harvested from woodlands. Herbal plants such as ginseng and goldenseal, specialty mushrooms like shiitake and reishi, and wild foods such as fiddlehead ferns and miner’s lettuce that grow in forests are examples of NTFPs. Forest farming is an agroforestry practice that diversifies forest management and enhances associated income opportunities. It also improves forest composition and structure and long-term health, quality and economic value. It also improves woodland composition and structure and long-term health, quality, and economic value (Table 11-3).

Forest farmers actively monitor and manage interactions between trees and understory crops with long-term woodland health and productivity in mind. Both timber and non-timber crops can be managed on the same forested land, or non-timber crops can be grown in forests where timber harvesting is not possible or desired. Forest farming operations range from very small (less than half an acre) to very large (greater than 50 acres).

Forest farming design considerations differ based on the NTFP being farmed. There are four forest farming methods:

1. Woods-grown: Woods-grown, also known as forest gardening, is most intensive. In addition to potential thinning of the forest overstory, it often involves clearing undesirable vegetation in the understory and other practices that are more closely related to agronomy (e.g., tillage, fertilization, weeding, and control of disease, insects, and wildlife). Due to costs associated with input levels, forest gardening can be costly and time consuming but can render large NTFP yield.
2. Wild-simulated: Wild-simulated is the cultivation of NTFPs in natural growing environments. A natural growing environment can deliver products similar in appearance and quality to plants naturally growing in the wild. Rather than administer intensive agronomic practices, wild-simulated forest farmers use minimally invasive techniques to expose the soil, and plant seeds or plants. Fertilizers and pesticides are rarely used. Despite potential decreases in total yields, wild-simulated products often have higher priced markets when compared to those that are more intensively cultivated.
3. Managed wild population: Managed wild populations involves working with plants or fungus that already exist. The forest canopy may be modified to favor growth of desirable NTFPs. Understory plants that are competing with the desired species may be removed. Annual harvests might not be possible. Inputs are very low and yields vary depending on the species and how often it is harvested.
4. Wild-harvest or Wild craft: Wild-harvesting is the harvesting of NTFPs growing naturally in the forest. It is not generally considered forest farming because active management is not involved. There are no inputs and no risks. There are sustainable wild-harvest methods that can be followed to ensure future harvests.

Start small when establishing a forest farming operation. A successful forest farmer stated that it takes multiple years to master NTFP cultivation. The first few years are typically filled with a mix of successes and failures in terms of growing and marketing. The next few years are a time to leverage lessons learned to refine production, increase efficiency, and build on developed markets. Starting small allows a forest farmer to gain experience and suffer some setbacks without losing large amounts of money. Small areas can be used to test different crops, sites and management practices. Initial operations usually focus on two or three crops, but can include more if markets and labor are not a limiting factor.

Consult your local forester or Master Gardener for assistance in designing your forest farming.