A free email agroforestry journal for practitioners, extension agents, researchers, professionals, students, and enthusiasts. One edition is sent each month focusing on a concept related to designing, developing, and learning more about trees and agroforestry systems. Focuses on trees and their roles in agriculture, natural ecosystems, human culture and economy.

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Overstory #75 - Glossary for Agroforestry Practices

Editors note

During the past three years, The Overstory has covered a wide range of topics and many agroforestry terms have been used. This edition features an agroforestry glossary (collection of specialized terms and their meanings) complied and edited by special guest contributors Peter Huxley and Helen van Houten. Here you will find the meanings of 23 of the 1400 terms found in the full version of Glossary for Agroforestry. The glossary was originally published by the International Centre for Research in Agroforestry (ICRAF).

"If people defined their terms, arguments would be less than three minutes."

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Overstory #74 - Microenvironments (Part 2)

Editor's note

A microenvironment is small-scale environment which differs from its surroundings (such as shade under a tree canopy, a windbreak, or a distinct soil pocket). In the first part of this two-part series on microenviroments (Overstory #72), special guest author Robert Chambers discussed the importance of microenvironments to sustainable livelihoods. In this edition, Dr. Chambers discusses how producer-based, participatory research can legitimize and strengthen microenviroments for sustainable development.


The biases in both agricultural and social sciences combine to hide microenvironments (MEs) from sight, to understate or exclude them in statistics, and to undervalue their importance for livelihoods. In addition, there are other factors specific to the nature of MEs which conceal them from view or insulate them from attention. These can be understood by considering examples of MEs and reflecting on some of their characteristics.

There are many reasons why professionals have neglected MEs, including: Smallness and dispersal.

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Overstory #73 - Buffers: Common Sense Conservation

Conservation buffers are a common-sense way for you to protect your most valuable asset--your land--and demonstrate your personal commitment to conservation.

Best described as strips or small areas of land in permanent vegetation, conservation buffers help control potential pollutants and manage other environmental concerns. Filter strips, field borders, grassed waterways, field windbreaks, shelterbelts, contour grass strips, and riparian (streamside) buffers are all examples of conservation buffers.

Conservation buffers can be especially helpful in maintaining a productive, profitable, and responsible farming or ranching operation. Farms and ranches today produce more than crops and livestock. They also produce environmental benefits, and conservation buffers can help you protect soil, air, and water quality; improve fish and wildlife habitat; and demonstrate a commitment to land stewardship.

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Overstory #72 - Microenvironments (Part 1)

Editor's note

Agroforestry systems are often characterized by diversity and complexity. This includes a diversity of microenvironments (small-scale environments different from their surroundings, such as deep shade under a tree canopy). In this edition of The Overstory, guest author Robert Chambers discusses the importance of microenvironments to sustainable livelihoods.


Most agriculture creates or alters environments, through ploughing, irrigation, the effects of crop canopies, effects of grazing and browsing, and so on. A microenvironment (ME) is a distinct small-scale environment which differs from its surroundings, presenting sharp gradients or contrasts in physical conditions internally and/or externally. Microenvironments can be isolated, or contiguous and repetitive. They can be natural, or made by people or domestic animals.

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Overstory #71 - Nontimber Forest Products (Temperate)

Editor's Note

Nontimber forest products (NTFPs), also known as "nonwood," "minor," "secondary," and "special" or "specialty" forest products, involve an existing forest or woodland, and intentionally cropping something other than trees. The practice may or may not involve cultivation--the intention is to manage the forest for nontimber crops. This kind of cropping can be done in any kind of forest and has been traditional in many parts of the world. With careful planning, forest farming can be done in conjunction with other agroforestry practices.

This edition of The Overstory by guest author Deborah Hill of the University of Kentucky focuses on nontimber crops of forests in the continental United States. Although the focus is primarily temperate, NTFP producers will be interested in the management techniques described for a wide variety of commercial crops. Forest farmed products include mushrooms, botanicals of medicinal or culinary value, fruits and nuts, craft materials, maple and other syrups, and baled pine straw. Other, more traditional wood products such as fenceposts and fuelwood are also possibilities, while the raising of honeybees (apiculture) is yet another option.

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Overstory #70 - Troubles in the Rhizosphere

Editor's Note:

This is the third in a three part series by special guest author Dr. Alex L. Shigo, retired chief scientist of the U.S. Forest Service and author of numerous books including Modern Arboriculture. Dr. Shigo describes the importance of the root-soil interface (the rhizosphere), and how trees depend on healthy relationships with numerous soil organisms.

Troubles in the Rhizosphere

The rhizosphere is the absorbing root-soil interface. It is the zone, about one millimeter in width, surrounding living root hairs and the boundary cells of mycorrhizae as well as hyphae growing out from some mycorrhizae.

The rhizoplane is the boundary where soil elements in water are absorbed into the tree. Under an electron microscope, the rhizoplane appears as a jelly where microorganisms and tree cells mix, making it impossible to tell which side is tree and which is soil.

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