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Shibu Jose, Harold E. “Gene” Garrett, Michael A. Gold, James P. Lassoie, Louise E. Buck, and Dean Current

Agriculture is in the midst of a 21st century technological revolution, and we are well into the digital age of farming. The development of agriculture over 10,000 yr, including the technological advancements of the 20th century, has helped push the world population to 7.5 billion, with projections of 9.8 billion by 2050 (Searchinger et al., 2018). While the Green Revolution has helped to feed billions of people, the global environmental footprint of modern agriculture threatens the very existence of the socio‐ecological system in which we live (Funabashi, 2018). The natural resource base, including soil and water, that supports agriculture is experiencing immense pressure. The world is looking for sustainable solutions not only for food security but also for environmental security for the burgeoning population (Searchinger et al., 2018).

The United States led the agricultural revolution with a massive commitment to enhancing food and fiber production capabilities. The overall strategy was to become self‐sufficient with respect to agricultural crops and timber while improving the health and welfare of rural Americans. Obviously, this was successful within well‐defined limits—today, food remains plentiful and relatively inexpensive, the timber famine was averted, and forest and farm lands abound. Such gains, however, did not come without some high environmental costs, and by the 1970s the public was demanding more environmentally benign land use practices (Laurence, 1987).

As a consequence of the environmental transgressions committed during the construction of our industrialized nation, new criteria for defining successful land use management strategies were identified during the late 1980s (Turner, 1988). Sustainability, stability, and equability have now joined increased production efficiency as objectives for agriculture (Conway, 1987), and forestry is developing new management strategies that optimize the yield of many products and multiple uses rather than merely maximizing the production of one—timber (Coufal & Webster, 1996; Gillis, 1990; Maser, 1994). But what about the hybrid between agriculture and forestry that is practiced worldwide—integrative management systems far more common than the developed world’s often myopic approach to the production of a limited number of monocultures? Many professionals believe that agroforestry is a strategy for sustainable land use management that might be useful throughout North America (Garrett et al., 1994; Gold & Hanover, 1987; Kremen & Merenlender, 2018; Wiersum, 1990).

As we have moved into the 21st century, concerns have been raised about our dependence on foreign sources of fossil fuels, and the CO₂ emissions from our past and continued use of fossil fuels have increasingly been linked to global warming issues. The production of biofuels and energy from herbaceous and woody biomass has become a major interest with increasing amounts of research funding and private investment. Agroforestry practices combining herbaceous and woody species could play an important role in both the production of biomass for biofuels and energy as well as systems that enhance the ability of agricultural cropping to sequester and store carbon without the ecological problems of currently utilized agricultural systems (Downing, Volk, & Schmidt, 2005; Feliciano, Ledo, Hiller, & Nayak, 2018; Gruenewald et al., 2007; Holzmueller & Jose, 2012; Peichl, Thevathasan, Huss, & Gordon, 2006; Schoeneberger, 2005; Volk et al., 2006; White et al., 2007).

Because of its diversity, defining agroforestry could easily occupy an entire article—in fact on a number of occasions, it has (see Atangana, Khasa, Chang, & Degrande, 2013, pp. 35–47; Elevitch, Mazaroli, & Ragon, 2018; Lundgren, 1982; Nair, Viswanath, & Lubina, 2017). Presently, the concepts and practices of agroforestry in the United States are reasonably well understood within most professional circles to include “… intensive land management that optimizes the benefits (physical, biological, ecological, economic, social) arising from biophysical interactions created when trees and/or shrubs are deliberately combined with crops and/or livestock” (revised from Garrett et al., 1994). In identifying a niche for domestic agroforestry, emphasis must be directed toward a practice meeting the requirements of the four I’s–that is, it must be intentional, intensive, integrative, and interactive. As discussed below, the options available under this definition are many (also see Chapter 2; Gold & Hanover, 1987; Campbell, Lottes, & Dawson, 1991; Schultz, Colletti, & Faltonson, 1995). Agroforestry practices in the North America involve more than the production of single products (e.g., monoculture field crops, livestock feedlots, forest plantations, biomass plantings, etc.), the extensive collection of special forest products (e.g., floral greens, mushrooms, wild game, etc.), or the extensive grazing of livestock in woodlots or on open ranges. This is not to minimize the importance of such land uses, but each one is already well supported by an established knowledge base and a well‐educated group of practicing management professionals. Combining such practices into agroforestry arrangements that are ecologically sound and economically viable is a totally different story!

Intensive production of agricultural and forestry monocultures is found in both advanced, developed countries (e.g., corn [Zea mays L.], soybean [Glycine max (L.) Merr.], pine [Pinus spp.], fruit and nut orchards, vineyards) and many tropical regions in the form of woody perennial tropical tree, shrub, and vine crops including oil palm (Elaeis spp.), rubber [Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.], tea [Camellia sinensis (L.) Kuntze], coffee (Coffea spp.), pepper (Piper nigrum L.), and vanilla (Vanilla planifolia Jacks.) (Chambers, Pacey, & Thrupp, 1989; Jha et al., 2014; Liu, Kuchma, & Krutovsky, 2018; Pacheco, Gnych, Dermawan, Komarudin, & Okarda, 2017; Richards, 1985). On the other hand, agroforestry has remained the primary land use approach most common throughout the developing world (King, 1987; Mercer, 2004), where complex indigenous farming systems for food, fiber, and forage production have operated effectively for centuries (Nair, 1993). Not only have such agroforestry systems produced a variety of commodities for home use and/or sale, it is likely that they have offered a level of environmental protection unmatched by most modern land use technologies. Such dual features—production and protection—have become the basis for the concept of sustainability, which is now central to international development activities aimed at breaking the negative feedback relationship between intensive land use and progressive environmental degradation. Similarly, concepts such as “productive conservation” and “multifunctional agriculture,” which combine production agriculture with conservation by introducing more sustainable agricultural practices, are increasingly being discussed as options in more developed countries and could easily incorporate agroforestry principles (Jordan, et. al., 2007). For example, the five principles of sustainable food and agriculture defined by the FAO (2018) include: (a) increase productivity, employment, and value addition in food systems, (b) protect and enhance natural resources, (c) improve livelihoods and foster inclusive economic growth, (d) enhance the resilience of people, communities, and ecosystems, and (e) adapt governance to the new challenges.

About four decades ago, agroforestry was “discovered” by the international scientific community as a practice in search of a science (Steppler, 1987). Since that time, an increasingly extensive research base has been developing to help understand, improve, and apply indigenous agroforestry practices in developing nations of the world (Nair, 1996; Garrity et al., 2010; van Noordwijk et al., 2019). Around the same time, academics started asking how such practices might be applied in more developed countries (e.g., Campbell et al., 1991; Gold & Hanover, 1987; Lassoie, Teel, & Davies, 1991). However, agroforestry practices were not new in the temperate context either. Native Americans, across what is now the United States and Canada, have been practicing indigenous forms of what could be termed landscape‐scale agroforestry for millennia (Rossier & Lake, 2014). In the early decades of the 20th century, agroforestry plantings were done in the United States and Canada in the form of windbreaks and shelter belts as a response to the Dust Bowl of the 1930s. In the temperate zone, science‐based agroforestry biophysical and socioeconomic research and practice gained attention in the1980s and has strongly increased in the past 40 yr. Interest in domestic agroforestry has continued to grow, particularly as the dual needs for enhanced environmental protection and new economic opportunity have increased in importance (Brown, Miller, Ordonez, & Baylis, 2018; Garrett et al., 1994; Jose, 2009; Jose, Gold, & Garrett, 2018). The realization that agroforestry systems are well suited for diversifying farm income while providing environmental services and ecosystem benefits has increased receptivity on the part of landowners (Rois‐Díaz et al., 2018) Agroforestry systems offer great promise for the production of biomass for biofuel, specialty and organic crops, pasture‐based dairy and beef, among others. Agroforestry also offers proven strategies for carbon sequestration, soil enrichment, biodiversity conservation, and air and water quality improvement not only for the landowners or farmers but for society at large (Dollinger & Jose, 2018; Holzmueller & Jose, 2012; Scherr & McNeely, 2007, 2008; Udawatta & Jose, 2012).

In this chapter, we demonstrate the linkages among emerging integrated management systems for agriculture and forestry and indicate possible roles that agroforestry could play in the continuing development of these new land use strategies. Opportunities for the development of domestic agroforestry practices are identified and progress toward meeting them highlighted. Possible approaches to overcoming constraints limiting the development of agroforestry in the United States are suggested. It is our purpose to provide a framework for the chapters that follow and to stimulate creative thinking and proactive behavior by scientists and management professionals responsible for developing and implementing new land use management strategies that are environmentally, socially, and economically sustainable.