Agroforestry systems similar to the traditional shifting cultivation systems represent a valuable conservation tool for the Amazon basin. Agroforestry integrates agriculture with timber species and high diversity forest; silvopastoral systems are similar and combine cattle ranching with forestry. Valuable crops such as coffee and cacao are frequently cultivated under the canopy of tropical forest. Although these crops are frequently cultivated in full sun, shade cultivation provides greater biodiversity value and often creates a higher value product.
In conventional agricultural systems, annual plants are planted and harvested, removing the majority of the biomass from the farm. Because little plant material is returned to the soil, fertilizers are often needed to maintain yields; because the farm consists of just a few plants species, chemicals are often needed to ward of pests. Agroforestry, on the other hand, integrates numerous species of variables ages to create a closed system where no outside inputs are necessary. Perennial plants such as fruit trees allow farmers to remove only a fraction of the total biomass. Intercropping and alternating with nitrogen fixing plants such as legumes allows the farm to self-fertilize; greater diversity also offers greater protection against pests. Agroforestry in the Amazon basin utilizes fruit trees such as avocado, cocoa, guava, guaba (Inga spp.), citrus, and plantains. Palms include palm heart (Euterpe precatoria, Bactris guisapeas, and others), and palm fruits from Bactris guisapeas (peach palm), Euterpe oleracea (acai), Mauritia flexuosa, and Oenocarpus bataua. Annuals such as pineapple, manioc, tomato, pepper, and peanut, are planted, as well as various beans and tubers.
Fast growing timber species are also planted in shifting cultivation plots, such as Spanish cedar (Cedrela odorata), Brazilian fire tree (Schizolobium parahyba) and bolaina (Guazuma crinita). Most of these trees can be harvested for timber often after just 10-20 years, after which some nutrients have been returned to the soil. In the várzea, or floodplain forests, fast growing trees such as Calycophyllum spruceanum are managed in fallows and agroforestry systems by smallholders (see research by Yale F&ES graduates Robin Sears (MF ‘96) and Miguel Pinedo-Vasquez (Phd ‘96) in Human Ecology). In the foothills of the Andes, valuable species include pigue (Piptocoma discolor) and aliso (Alnus acuminata) for timber and chachafruta (Erythrina edulis) and avocado for fruit. Recent studies have indicated that these traditional shifting agriculture and agroforestry systems can be biodiverse, complex, and efficient: see worldwide analysis in Trends in Ecology and Evolution and for the Amazon in Royal Society. Interestingly, this history of management and tree selection may be one of the factors that facilitate the high tree diversity in the Amazon forest.
Chocolate, or cocoa, is an agroforestry plant from the forest shrub (Theobroma cacao), native to the Amazon basin. Today, most cocoa is cultivated in West Africa in full sun plantations, and commercial chocolate is processed with high quantities of sugar. In the Amazon basin, however, high quality chocolate varieties are still cultivated in the shade of the rainforest, usually in lowlands below 1,000 meters elevation. Similar to coffee, full sun plantations (Forastero variety) can achieve higher yields, but shade cocoa (Criollo variety) develops greater flavor quality and offers biodiversity and pest control benefits. Also, forest habitats have been found to improve the pollination success of coffee and cocoa plants. See a review of shade cocoa at World Agroforestry Center and in Ambio. Yale F&ES alum Judy Logback (MF ‘10) founded Kallari chocolate, a cooperative of indigenous Kichwa cocoa farmers in the Ecuadorian Amazon.
High quality Arabica coffee is cultivated in the foothills of the Andes, Central America, and southern Brazil. Brazil is the largest producer in the world, but most cultivation is centered outside of the Amazon basin, in the southern hills of Minas Gerais, Sao Paolo, and Paraná. Modern coffee cultivation is practiced in full sun, where yields can be higher and damage from the coffee rust fungus (Hemileia vastatrix) may be less. However, full sun coffee may be more susceptible to wind and frost damage, often requires expensive agrochemical inputs, and can lead to soil erosion. Shade coffee, on the other hand, provides biodiversity benefits and may be more sustainable in the long term (see a review of shade coffee in BioScience). Certification programs such as Rainforest Alliance, Bird Friendly, Fair Trade, and Organic seek to recognize the added value of shade coffee production and provide economic and social benefits for coffee producers.
Other forms of agroforestry include silvopastoral systems, where cattle grazing can be combined with forest management. As with cultivation of annual crops, soil fertility for pasture grass drops rapidly after a few years of use. This fertility can be restored by allowing the pasture fallow to return to forest, and facilitated by planting fast growing pioneer trees. In the Andes, aliso (Alnus acuminata) is particularly valuable because it fixes nitrogen in the soil and can improve grass production (see study in Frontiers in Ecology and the Environment). Other silvo-pastoral systems use high nutrient fodder plants such as Leucaena leucocephala to augment cattle production while maintaining greater farm area in forest (see review in Forest Ecology and Management). Studies also find that these systems can sequester high quantities of carbon, thus serving as a mean for climate change mitigation.
Fraser, Barbara. “Amazon smallholders use fast-growing timber to supplement income” CIFOR blog. August 15, 2013.
Lipske. M. (2015). Chocolate and Conservation. National Wildlife Federation. Retrieved from http://www.nwf.org/News-and-Magazines/National-Wildlife/Green-Living/Archives/2003/Chocolate-and-Conservation.aspx
Montagnini, F., & Nair, P. K. R. (2004). Carbon sequestration: an underexploited environmental benefit of agroforestry systems. Agroforestry systems, 61(1-3), 281-295.
Murgueitio, E., Calle, Z., Uribe, F., Calle, A., & Solorio, B. (2011). Native trees and shrubs for the productive rehabilitation of tropical cattle ranching lands. Forest Ecology and Management, 261(10), 1654-1663.
Padoch, C., Inuma, J. C., De Jong, W., & Unruh, J. (1985). Amazonian agroforestry: a market-oriented system in Peru. Agroforestry Systems, 3(1), 47-58.
Rice, R. A., & Greenberg, R. (2000). Cacao cultivation and the conservation of biological diversity. AMBIO: A Journal of the Human Environment, 29(3), 167-173.
Ricketts, T. H., Daily, G. C., Ehrlich, P. R., & Michener, C. D. (2004). Economic value of tropical forest to coffee production. Proceedings of the National Academy of Sciences of the United States of America, 101(34), 12579-12582.
ter Steege, H., Pitman, N. C., Sabatier, D., Baraloto, C., Salomão, R. P., Guevara, J. E., … & Fine, P. V. (2013). Hyperdominance in the Amazonian tree flora. Science, 342(6156), 1243092.
Unruh, J. D. (1990). Iterative increase of economic tree species in managed swidden-fallows of the Amazon. Agroforestry Systems, 11(2), 175-197.
Weber, M., Günter, S., Aguirre, N., Stimm, B., & Mosandl, R. (2008). Reforestation of abandoned pastures: silvicultural means to accelerate forest recovery and biodiversity. In Gradients in a tropical mountain ecosystem of Ecuador (pp. 431-441). Springer Berlin Heidelberg.