One of the most valuable timber species in the Amazon basin is big leaf mahogany (Sweitenia macrophylla), a timber highly valued for its color and quality. Mahogany harvest has driven loggers into the Amazonian forest for centuries; although mahogany trees comprise only a small percentage of the total trees harvested in the Amazon, a single tree can sell for thousands in a US market.
Big leaf mahogany is found from the wet forests of Yucatan, Mexico all the way south into the Amazon of Brazil and Bolivia. In the Amazon, it is less common in the interior of the basin and more common on the southern periphery where rainforest transitions into Cerrado woodland, because of drier and seasonal climatic conditions. Mahogany establishment is somewhat dependent on this seasonal rain forest with distinct wet and dry seasons, as well as large scale disturbance from hurricane, fire, or flood. Other species of true mahogany are found in the Caribbean and the Pacific coast, while similar species in the same family (Meliaceae) are found in Africa.
Seeds of mahogany germinate in shade of the canopy, but often grow best when exposed to sunlight. In Central America and Mexico, this regeneration is thought to be tied to seasonal hurricanes. In the Amazon basin, however, regeneration may be correlated to seasonal fires or floods, while some argue that it is not tied to disturbance at all. In many areas across its range, mahogany is most often found in low lying wet areas along streams. Trees usually begin to flower around 10-12 yrs, are insect pollinated, and form fruit capsules 10-12 months after pollination. Seeds are wind dispersed in the dry season, close to the parent tree, when the trees are leafless (June-November in the seasonal forests of the southeastern Amazon). Seeds germinate in a few months but have a short life and are not drought tolerant.
Sustainable management of mahogany is complex. Many silviculturalists argue that mahogany needs large canopy openings to regenerate and that the small gaps from selective logging are too small. In dry forests of the Bolivian Amazon, mahogany regenerates best in large patches of flood and erosion disturbed area, and poorly in selective logging gaps. In Para, Brazil, researchers also found that mahogany seedlings have poor survival in logging gaps, and that logged trees should be felled towards the west, because this is where wind has most likely carried seedlings from the season before. In some areas, it is likely that human disturbance from indigenous shifting cultivation systems partially mimic the natural disturbance that favors regeneration of mahogany and Brazil nut. See more research from Yale scientists James Grogan (Phd ‘01) and Mark Ashton (Phd ‘90) regarding mahogany regeneration in the Brazilian Amazon (Forest Ecology & Management 2003 and 2005).
Conservation of mahogany has attracted international attention as natural populations have plummeted. In 2001, Brazil banned mahogany trade in 2001 following allegations of illegal activity. Following this, mahogany was listed in 2003 as CITES II, an international trade regulation that restricts trade so that it does not harm the ecosystem in where the species is harvested. Today, mahogany harvesters in Brazil are required to retain 20% of commercial trees and perform enrichment plantings in log landings. In spite of the CITES listing in Brazil, illegal trade continues, and also may have shifted to other countries with untapped forest and weaker forest governance, like Bolivia and Peru. In 2007-2008, Peru signed a free trade agreement with the United States, and stipulations of the trade treaty supported increased enforcement of trade of mahogany and other CITES listed timber species. Nevertheless, illegal logging has continued in Peru and has been the subject of detailed investigative analysis. Recently, some estimate that 80% of Peru’s mahogany is traded to the United States. James Grogan and authors describe the population distribution and conservation status of big leaf mahogany in a 2010 article in Conservation Letters.
Brown, N., Jennings, S., & Clements, T. (2003). The ecology, silviculture and biogeography of mahogany< i>(Swietenia macrophylla):</i> a critical review of the evidence. Perspectives in Plant Ecology, Evolution and Systematics, 6(1), 37-49.
Chimeli, A., & Boyd, R. (2010). Prohibition and the Supply of Brazilian Mahogany. Land Economics, 86(1), 191-208. Retrieved from http://muse.jhu.edu/journals/land_economics/summary/v086/86.1.chimeli.html
Cotta, J. N., Kainer, K. A., Wadt, L. H., & Staudhammer, C. L. (2008). Shifting cultivation effects on Brazil nut (< i> Bertholletia excelsa</i>) regeneration. Forest Ecology and Management, 256(1), 28-35.
Grogan, J., Ashton, M. S., & Galvão, J. (2003). Big-leaf mahogany (Swietenia macrophylla) seedling survival and growth across a topographic gradient in southeast Pará, Brazil. Forest Ecology and Management, 186(1), 311-326.
Grogan, J., & Barreto, P. (2005). Big‐leaf mahogany on cites appendix II: Big challenge, big opportunity. Conservation Biology, 19(3), 973-976.
Grogan, J., Blundell, A. G., Landis, R. M., Youatt, A., Gullison, R. E., Martinez, M., … & Rice, R. E. (2010). Over‐harvesting driven by consumer demand leads to population decline: big‐leaf mahogany in South America. Conservation Letters, 3(1), 12-20.
Grogan, J., Jennings, S. B., Landis, R. M., Schulze, M., Baima, A., Lopes, J., … & Zimmerman, B. L. (2008). What loggers leave behind: Impacts on big-leaf mahogany ( Swietenia macrophylla) commercial populations and potential for post-logging recovery in the Brazilian Amazon. Forest Ecology and Management, 255(2), 269-281.
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Upper Amazon Conservancy. (2011). Upper Amazon Conservancy Investigation Exposes Illegal Logging in Murunahua Reserve. Retrieved from: http://upperamazon.org/illegal-mahogany-loggers-penetrate-heart-of-uncontacted-tribal-reserve/
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