Читать книгу North American Agroforestry - Группа авторов - Страница 17

Although not defined as such until recently (Garrett et al., 1994; Gold & Hanover, 1987; Gordon & Newman, 1997; Rossier & Lake, 2014; Sinclair, 1999; Torquebiau, 2000), agroforestry‐like practices have been part of North America’s heritage. Native Americans and European pioneers practiced subsistence lifestyles based on integrated land use strategies that were similar in principle to the agroforestry being practiced by indigenous populations in today’s developing countries (Carroll, 1973; King, 1987; Rossier & Lake, 2014; Russell, 1982). The widespread use of these strategies, however, largely disappeared during the last century with the concurrent development of separate agricultural and forestry research and management infrastructures. Today, an integrated, subsistence lifestyle is the chosen standard of living for a few independent, free‐spirited individuals and an unfortunately necessary one for the economically marginalized rural poor. A few agroforestry practices survived into the mid‐20th century associated with long‐established organizations (e.g., the Northern Nut Growers Association) or as culturally acceptable complements to traditional farming enterprises (e.g., maple syrup production).

Periodic agricultural disasters have stimulated unique forestry activities that can also be considered agroforestry practices. In the 1930s, the Great Depression combined with the drought‐induced Dust Bowl in the Great Plains caused severe economic and environmental perturbations throughout the agricultural community and the nation. The formation of the Civilian Conservation Corps promoted many conservation activities including the planting of millions of trees as windbreaks and plantations to help protect eroding farmlands (Hudson, 1981). Such ecological problems also stimulated interest in the use and genetic improvement of nut trees to reclaim and promote production from lands marginal for conventional farming practices (Smith, 1950). The farm crisis of the 1980s was less dramatic on a large scale, but it had devastating economic and social impacts on many rural communities (Fitchen, 1991). In response, congressional actions established alternative agricultural programs such as the Conservation Reserve Program, Low Input Sustainable Agriculture (renamed the Sustainable Agriculture Program), and the Integrated Pest Management Program.

In the first decade of the 21st century, there was an increased interest in the production of biofuels and a concerted government effort to develop the technologies to make biofuels a reality. One unintended impact of the interest and support for biofuels, and particularly corn‐based ethanol, has been periodic increases in corn prices in the United States and around the world, igniting a “food versus fuel” debate. High commodity prices linked to the demand for biomass feedstocks for biofuels coupled with huge demand from China also resulted in farmers opting out of conservation programs and replacing conservation acres with commodity crops, with environmental consequences including increasing sediments and chemicals entering surface and ground waters (Jordan et al., 2007).

Simultaneously, spurts of environmental consciousness by the American public have promoted alternate land use practices, often involving unique mixes of trees, food crops, and livestock by non‐traditional rural landowners. For example, the 1960s spawned a group of “back‐to‐the‐land” environmentalists desiring low‐impact communal lifestyles. Although most of these groups eventually disappeared, individuals committed to integrated land use practices remained to practice their more ecosystem‐friendly forms of agriculture and to develop such organizations as the Land Institute, Rodale Research Center, and Wallace Center. The fact that the Northern Nut Growers Association was founded in 1910 is a testimony to the existence of such individuals for many years.

The past 40 yr have witnessed a growing understanding of the potential usefulness of agroforestry practices in addressing today’s concerns over the economic and environmental sustainability of forest and farm lands. Gold and Hanover (1987) discussed two such practices: managing conifer sawlog with cattle grazing practices (silvopasture) and multi‐cropping valuable hardwoods with agricultural crops (alley cropping). There are five widely recognized agroforestry practices in the United States today: (a) alley cropping, (b) riparian and upland buffers, (c) windbreaks, (d) silvopasture, and (e) forest farming. In addition to the five recognized practices, there is an emerging agroforestry practice called urban food forests that has gained considerable attention in the past decade (Bukowski & Munsell, 2018). The specifics concerning these six practices are examined later in this volume. In addition, with the growing interest in terrestrial carbon sequestration and alternative fuels provided by woody and herbaceous growth, there has been increasing interest in the role of agroforestry practices to sequester and store carbon as well as systems that produce biofuels. The National Agroforestry Center has continued to add support to those practices, providing publications and guidance to landowners and practitioners (Schoeneberger, 2005; USDA, 2015, 2019). Much progress has been attained toward the building of research, education, and application for domestic agroforestry that will foster the development of these practices (Gold, 2007; Gold, Hemmelgarn, & Mendelson, 2019; Gold & Jose, 2012). However, before discussing these concepts relative to the challenges still facing the development of agroforestry in the United States, we must first provide an appropriate context by considering opportunities for its development.