shiitake mushrooms (Lentinula edodes (Berkeley) Pegler), decorative ferns and spring ephemerals grown in the understory are sold for medicinal, botanical, food, decorative and handicraft, and landscaping products. Overstory trees are managed for high‐value timber or veneer logs.
Urban Food Forests
In addition to the five recognized practices, there is an emerging, sixth agroforestry practice. Urban Food Forests, have gained considerable attention over the past decade (Lovell, 2010; Clark and Nicholas, 2013; Bukowski and Munsell, 2018; Park et al., 2019). Urban Food Forests are defined as: i) The intentional use of perennial food‐producing plants to improve the sustainability and resilience of urban communities (Bukowski and Munsell, 2018); 2) A food forest is an edible, perennial, polyculture system that is designed and managed to mimic multistory forest structures and to function like a natural, self‐sustaining forest (Park et al., 2018). The term food forest signifies an intentionally designed, highly integrated community of plants that has various vertical and horizontal plants and root layers that collectively provide edible products (Bukowski and Munsell, 2018). Urban food forestry is an emerging multifunctional and interdisciplinary approach to increasing urban sustainability and resilience, particularly where food security is concerned, and provides a starting point for bridging gaps in knowledge and practice between urban agriculture, urban forestry, and agroforestry. Also, as noted in Bukowksi and Munsell (2018), another commonly used term is community food forests.
Clark and Nicholas (2013) note that urban food forestry is a viable and important strategy to address multiple sustainability challenges (e.g., food security, climate change, and poverty), to contribute to human health by increasing affordable public access to and consumption of nutrient dense foods to combat hunger and obesity, and can be also used to promote sustainable urban development through providing enhanced ecosystem services.
Is it Agroforestry?
A key concern in developing agroforestry nomenclature for the United States and Canada is overlap and confusion with mainstream land use management disciplines, for example forestry, agriculture, and livestock production. A fundamental need was to develop a definition and criteria that would effectively distinguish practices that are agroforestry from those that are not (Garrett et al., 1994). Application of the four criteria defining agroforestry (intentional, intensive, integrative, and interactive) provides the key to determine what is and is not an agroforestry practice. Using these criteria, we have the basis to explain how variations of common land use practices can be properly described as agroforestry. The following examples are agroforestry because they satisfy all four of the criteria defining agroforestry.
Special Forest Products
Deliberate cultivation of an understory specialty crop beneath a forest canopy that has been modified and managed to provide the appropriate microclimate conditions in the understory is an example of forest farming (e.g., woods cultivated or wild simulated ginseng). The practice is created by design, is intensively managed, is integrated, and beneficial interactions are utilized. Thus, it is agroforestry, as contrasted to the gathering of naturally‐occurring, unmanaged, specialty products (e.g., wild ginseng) from a natural forest stand.
Log‐grown shiitake mushrooms, deliberately cultivated under the shade of the forest canopy is a legitimate forest farming practice. The practice is created by design, is intensively managed, is integrated, and beneficial interactions are utilized. Thus, it is agroforestry, in contrast to the production of shiitake on indoor sawdust bales which yields a similar (but not nutritionally identical) product but does not qualify as forest farming.
Nut Plantations and Fruit Orchards
When nut or fruit culture (i.e., planted in a plantation or orchard format) is combined with row crop or forage production, it is alley cropping (Gold, 2019). Crops grown in the between‐row space can be changed over time to minimize competitive effects and/or adjust to changing market conditions. Windbreaks can be established to protect orchards in exposed, windy areas. They slow the wind, reduce water use, improve insect pollination, and increase pesticide use efficiency. In each case, the components are deliberately integrated and intensively managed within the plantation or orchard.
Managed Intensive Rotational Grazing
When trees are added to an existing pasture and the resulting area is managed for timber, forage and livestock, it is the agroforestry practice of silvopasture. The components are deliberately integrated and managed by design to enhance the biophysical interactions among components. Both the timber and forage components are designed to minimize competition and maximize complementarity. Neither opportunistic forest grazing nor grazing cattle without management within a plantation are agroforestry; both can be destructive to the forest, tree, and forage resources.
Agroforestry in the Landscape
A final issue to discuss is mosaics of monocultures in agricultural landscapes. Common features of agricultural landscapes throughout the United States and Canada are single‐crop farm fields, woodlots and tree plantations, wetlands, and grazing lands. A physical proximity does not constitute agroforestry at the landscape level because there is no intentional integration and there is minimal interaction among components. In contrast, an agricultural landscape that contains windbreaks or riparian and upland buffers, that is, linear plantings including permanent woody vegetation strategically placed to maximize conservation benefits and create biophysical interactions with other components of the agricultural system, clearly demonstrates agroforestry at a landscape scale. The subject is discussed further in Table 2–3, which outlines agroforestry concepts.
Table 2–3. Agroforestry concepts.
| Concepts/Comments |
| Cascades of benefits are derived from beneficial process‐level biophysical interactions created when trees and/or shrubs are deliberately combined with crops and/or livestock. |
| Additional benefits are often derived from component integration when compared with traditional, segregated (agriculture and forestry) production. Through intensive and careful management, desired interactions are optimized and undesirable interactions are minimized. Agroforestry practices introduce, restore, and enhance biological diversity and agroecosystem resilience at field, farm, watershed and landscape levels. |
| For many people, enhanced biodiversity is considered a benefit, e.g., increased wildlife; however, in agricultural regions, biodiversity must be managed to obtain desired effects like enhancement of selected fish, wildlife, and plant species. The challenge is to determine the type, amount and distribution of species that will provide an adequate level of desired benefits. |
| Agroforestry contributes to integrated pest management by creating favorable habitats and microclimates to enhance the extent and effectiveness of natural pest controls. |
| Agroforestry is an essential component of effective conservation buffers creating positive impacts upon steep slopes, highly‐erodible soils and collapsing streambanks. |
| Agroforestry contributes to the maintenance of soil quality and productivity by keeping soil in place, enhancing nutrient absorption and cycling, intercepting water‐borne pollutants, improving water filtration and retention capacity, and reducing flood damage. |
| Agroforestry increases the productive area of the farm by expanding use of vertical and horizontal space above‐ and below‐ground and fully exploiting the diversity of useable niches. |
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Agroforestry practices permit fuller use of the soil profile, maximize use of photosynthetic radiation,
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