Every year, small farmers in tropical Latin America advance farther into the jungle. They plant crops for several years. Then they leave the land fallow for five or ten years. That restores its fertility and helps control weeds. It also provides a source of medicinal plants, fuelwood, construction materials, and other products. If war or personal misfortune intercedes or the land is not suited for crops, the fallow may last much longer. That may also happen if farmers lack sufficient resources to bring their land back into production.

Leslie Holdridge, Gerardo Budowski, Ariel Lugo, Frank Wadsworth, and other great figures in Latin American forestry began talking about the importance of such ’secondary forests’ decades ago. Still, the forestry community has largely ignored these areas, treating them as if they were of little value. However, one man’s fallow is another man’s forest. (The same goes for women!) It all depends on what interests you. Secondary forests currently provide many forest products for household use, but little commercial timber. Data from the Amazon suggests they can sequester around five tons of carbon per hectare each year. Even so, a hectare of primary forest stores much more carbon in total than a young secondary forest. Secondary forests have a lot of biodiversity, but may not have the particular species you are looking for.

Researchers from the Center for International Forestry Research (CIFOR), the Tropical Agriculture Center for Research and Education (CATIE), the Brazilian Agricultural Research Company (EMBRAPA), La Molina Agricultural University, and the national university of Nicaragua (UNAN) have studied secondary forests a great deal lately. ’Secondary Forests and Integrated Resource Management in Colonist Swidden Agriculture in Latin America’ by Joyotee Smith et. al. presents results. It will appear shortly in ’World Forests, Markets, and Policies’ edited by M. Palo, J. Usivuori, and G. Merry. The authors consider any natural re-growth over five meters tall as secondary forest.

Households surveys in Bragantina and Guama in Para (Brazil), Pucallpa (Peru), and Rio San Juan (Nicaragua) show that the area in secondary forests increases steadily for several decades after farmers colonize a new area. Then it levels off at about 20-25% of total area. By then, most original forest has vanished and secondary forest constitutes the main forest resource. Farmers sometimes manage these forests to favor the few species with commercial value. A large portion of the trees in these secondary forests comes from re-sprouting, rather than from seeds, particularly in places with few remaining nearby sources of seeds.

No one needs to convince farmers to leave their land fallow. Farmers do it anyway. But policymakers and foresters may want to encourage them to retain their fallow longer and to manage it to produce more forest products and environmental services. To achieve that, Smith and her colleagues suggest:

* removing subsidies for livestock;

* controlling fires;

* improving fallow quality through enrichment planting;

* introducing high-value perennial crops;

* and paying farmers for carbon sequestration.