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A one-stop location for information on big-leaf mahogany (Swietenia macrophylla, Meliaceae)

CURRENT STATUS

Consumer demand for big-leaf mahogany has driven boom-and-bust logging cycles for centuries, depleting local and regional supplies from Mexico to Bolivia. A study by Martinez et al. (2008, see sources below), later published by Grogan et al. (2010), found that approximately 58 million hectares (21%) of mahogany’s historic range in South America (278 million hectares total) had been lost to forest conversion by 2001. Commercial populations had been logged from at least 125 million more hectares, reducing the current commercial range to 94 million hectares (34% of historic). Surviving mahogany stocks are extremely low-density populations in remote regions of Amazonia representing a smaller fraction of historic stocks than would be expected based on estimated current commercial range.

Updated natural range of mahogany in South America overlaid on forest cover based on 2001 satellite data. From Grogan et al. 2010.
Mahogany Model
Updated natural range of mahogany in South America overlaid on forest cover based on 2001 satellite data. From Grogan et al. 2010.
Estimated current distribution of mahogany populations in South America. From Martinez et al. 2008.
Mahogany Model
Estimated current distribution of mahogany populations in South America. From Martinez et al. 2008.

In Brazil, commercial mahogany populations survive across an estimated 35% of the revised natural range, or in 55 million hectares of natural forest. Most remaining populations are located in remote regions where transportation infrastructures remain incipient, or where terrain is steep, or where seasonal rains impede access. These populations occur mostly along the northern and western limits of mahogany’s range in the country, at low or very low densities compared to high-density populations that were once common in Rondônia and southeast Pará. The true extent of logging impacts in Brazil is likely far more extensive for reasons given in Martinez et al. (2008).

Estimated current distribution of mahogany populations in Brazil based on logging centers data. Left map shows extent of logging industry’s reach for mahogany in 1998. Right map shows remaining range (green) overlapping protected areas & Indigenous Lands (orange hatching) or already exploited (orange). From Grogan et al. 2010.
Mahogany Model
Estimated current distribution of mahogany populations in Brazil based on logging centers data. Left map shows extent of logging industry’s reach for mahogany in 1998. Right map shows remaining range (green) overlapping protected areas & Indigenous Lands (orange hatching) or already exploited (orange). From Grogan et al. 2010.

Approximately 30% (16.4 million hectares) of mahogany’s estimated remaining commercial range in Brazil falls within protected areas and Indigenous Lands. However, while protected areas and Indigenous Lands have been shown to slow deforestation rates across southern Amazonia, neither have afforded effective protection to mahogany populations within their borders. Only the current stringent regulatory environment can enforce the conservation status of these and other unprotected surviving mahogany populations in Brazil.

Estimated current distribution and abundance of mahogany populations in Bolivia. From Martinez et al. 2008.
Mahogany Model
Estimated current distribution and abundance of mahogany populations in Bolivia. From Martinez et al. 2008.

Decades of selective logging in Bolivia resulted in elimination of commercial populations of mahogany from 79% of its historic range by 2001. Approximately 14% of the range is protected, but densities within these areas are low. Illegal logging has occurred and continues to varying degrees in all legally protected areas within mahogany’s historic range in Bolivia. The most significant surviving populations occur in areas of difficult access in the northern Amazon region along the borders with Brazil and Peru, and within protected areas. High-density populations (more than one commercial tree per hectare) reportedly survive in the Isiboro-Secure National Park, while medium-density populations remain in other protected areas such as Amboró, Carrasco, and Madidi National Parks, and the Pilón Lajas Biosphere Reserve and Indigenous Territory.

Estimated current distribution and abundance of mahogany populations in Peru. From Martinez et al. 2008.
Mahogany Model
Estimated current distribution and abundance of mahogany populations in Peru. From Martinez et al. 2008.

Although forest cover remains relatively intact across mahogany’s historic range in Peru, decades of selective logging, especially intensive terra firme logging carried out since the early 1990s, had eliminated commercially viable populations from 50% of this area by 2001. The spike in mahogany exports from Peru after the 2001 moratorium in Brazil, and continued high export volumes under quotas set after the Appendix II listing went into effect, suggest that remaining stocks occupy significantly less than 50% of mahogany’s original natural range in Peru. Remaining populations are located mainly in the least accessible or most remote areas of the Peruvian Amazon, which correspond in large degree to protected areas and Indigenous Lands. The most important stands, those with the highest reported densities (0.1–1 trees/ha), occur near the border with Brazil’s western state of Acre within the Alto Purús Reserved Zone, a naturally isolated, roadless area located in the upper watershed of the Purús River; and in the northwestern section of Manu National Park. However, extensive illegal logging activities have been reported from these regions during the past decade.

Estimated current distribution and abundance of mahogany populations in Ecuador. From Martinez et al. 2008.
Mahogany Model
Estimated current distribution and abundance of mahogany populations in Ecuador. From Martinez et al. 2008.

Approximately 73% of mahogany’s historic range in Ecuador lacks commercial populations as a result of over-exploitation. There are presently no forestry concessions for mahogany in Ecuador and harvests are illegal. The most important remaining populations are probably located in the headwater region of medium-sized tributaries of the Napo River, that is, in adjacent watersheds of the Cusano, Nushiño, and Sotano Rivers. The lower slopes of the Sumaco volcano adjacent to the Sumaco-Galeras National Park may also harbor natural populations.

Estimated current distribution of mahogany populations in Colombia. From Martinez et al. 2008.
Mahogany Model
Estimated current distribution of mahogany populations in Colombia. From Martinez et al. 2008.

Roughly 50% of mahogany’s historic range in Colombia has lost forest cover. Despite the lack of detailed inventories, substantial deforestation and the absence of any significant trade contribute to the belief that mahogany is commercially depleted throughout the country. The most significant remaining natural populations of mahogany probably occur in the northern Pacific region of the Department of Chocó on the Panamanian border, encompassing the municipalities of Bahía Solano and Juradó; and in Indigenous Reserves located along the Domingodó, Opogado-Guaguando, Napipi, Alto Río Cuta, Uva and Pogue Rivers, particularly in the upper watershed areas which serve as buffer zones for Ensenada de Utria Natural National Park. Outside these areas, commercial stocks probably no longer exist, though mahogany may be present in logged forests or surviving forest fragments at extremely low densities.

Estimated current distribution and abundance of mahogany populations in Venezuela. From Martinez et al. 2008.
Mahogany Model
Estimated current distribution and abundance of mahogany populations in Venezuela. From Martinez et al. 2008.

As of 2001, 74% of mahogany’s original estimated range of 9.3 million hectares had been deforested in Venezuela, while decades of selective logging had eliminated commercial stands from 89% of mahogany’s range. Densities are estimated to be very low (fewer than 0.01 trees/ha) in approximately 87% of areas where mahogany can still be found, low (0.01 – 0.1 trees/ha) in 13%, and medium (0.1–1.0 trees/ha) in less than 1%. A little over half (51%) of the area where mahogany reportedly occurs is private property, with the remainder in National Parks (21%) and Forest Reserves (28%) under concession management. In general, it is difficult at present to locate unlogged natural mahogany populations in Venezuela.

In Mexico and Central America, 64% of mahogany’s historic range had lost forest cover by the mid-1990s, with remaining forest populations severely depleted by logging.

Estimated current distribution of mahogany in Mexico and Central America. From Calvo et al. 2000.
Mahogany Model
Estimated current distribution of mahogany in Mexico and Central America. From Calvo et al. 2000.

SELECTED SOURCES

Calvo JC, Bolaños R, Watson V & Jiménez H (2000) Diagnóstico de la caoba (Swietenia macrophylla King) en Mesoamérica: Visión general (Evaluation of Mahogany in Mesoamerica: General Overview). Tropical Science Center / PROARCA / CAPAS, San José, Costa Rica.

Grogan J, Barreto P & Veríssimo A (2002) Mogno na Amazônia Brasileira: Ecologia e Perspectivas de Manejo (Mahogany in the Brazilian Amazon: Ecology and Perspectives on Management). IMAZON, Belém, PA, Brazil. 58 pp. Available in Portuguese & English at www.imazon.org.br.

Grogan J, Blundell AG, Landis RM, Youatt A, Gullison RE, Martinez M, Kometter RF, Lentini M & Rice RE (2010) Over-harvesting driven by consumer demand leads to population decline: big-leaf mahogany in South America. Conservation Letters 3: 12-20.

Kometter RF, Martinez M, Blundell AG, Gullison RE, Steininger MK & Rice RE (2004) Impacts of unsustainable mahogany logging in Bolivia and Peru. Ecology and Society 9: http://www.ecologyandsociety.org/vol9/iss1/art12.

Martinez M, Blundell AG, Gullison RE & Grogan J (Eds.) (2008) Historic range and current status of big-leaf mahogany (Swietenia macrophylla) in South America. Report for the Center for Applied Biodiversity Science (CABS)–Conservation International, Washington, DC, USA.

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