Agroforestry has a long, rich history that is rooted in activities practiced by indigenous communities around the world. Native peoples were known to gather fruits, nuts, and understory herbs from the forest, based on their deep ecological knowledge of the natural system, and they often cultivated preferred species. For modern applications, agroforestry can be defined as the intentional integration of trees and shrubs with crops or livestock to create a multifunctional system with a wide range of benefits. In temperate regions, agroforestry is characterized by six key practices: (1) alley cropping—planting rows of trees with a companion crop grown between the rows; (2) forest farming—growing high-value specialty crops in the shaded forest understory; (3) riparian buffers—protecting water resources such as streams with a zone of trees, shrubs, and herbaceous plants; (4) silvopasture—combining trees, forage, and livestock for multiple products; (5) windbreaks—planting rows of trees and shrubs to protect crops or livestock from wind and to reduce soil erosion; and (6) urban food forests—integrating trees, shrubs, and herbaceous plants that provide edible products for the good of the community. The environmental benefits of agroforestry have been widely studied and continue to be a source of great interest. Most recently, the potential for agroforestry to contribute to climate change adaption and mitigation is being explored. While the science of agroforestry has been influenced to a great extent by the field of ecology and related disciplines, social science dimensions are increasingly captured through the study of adoption behaviors, preferences, and cultural benefits. The investigation of the role of economic and policy drivers is critical to understanding strategies to motivate landowners to adopt these practices at a level that would expand agroforestry into the mainstream. Landscape-level planning and design could provide a vision and a pathway for a broader transformation to a system that encourages perennial habitats including specialty crops that supply edible products. Such a strategy could place agroforestry more directly into the growing call to support regional food systems and positive human health outcomes. This article focuses on the trends and directions in agroforestry research primarily in North America, with emphasis on developments in the early 21st century.
Growing climatic sensitivity of U.S. agriculture linked to technological change and regional specialization
