ABSTRACT
Trees form part of the agricultural landscape in many parts of the world. When trees are intentionally retained or planted on land used for crop production or grazing, the resulting systems are considered examples of agroforestry (Chapter 18 of Agroecology: The Ecology of Sustainable Food Systems). Trees, or woody perennials more generally, can have a great many benecial ecological impacts on the overall productivity and stability of an agroecosystem. The objective of most agroforestry systems is to optimize these benecial effects and minimize the negative. But thorough agroecological knowledge of trees’ ecological roles and inŽuences are necessary to accomplish this goal.
