This prized timber species is one of the most commercially sought after mahoganies. Commercially known as Big Leaf Mahogany, this species is widespread, occurring in much of South and Central America. Despite this, due to national and international demand for mahogany, the population size of the species has rapidly declined. This species has been commercially traded for several centuries, leading to its commercial exhaustion from much of its northern range. Therefore, there is heavy harvest pressure in remaining contiguously forested areas, such as in Brazil and Bolivia. This has led the species to also become locally commercially exhausted, at some sites in these two countries and other parts of South America. The species is protected under national and international legislation but demand, such that it is, has led to the continued illegal logging of the species. Remaining trees are thought to be protected due to their inaccessibility. The species is intrinsically at risk due to poor natural regeneration, which is amplified by logging practices. Across the range of the species there has been a decline in the area in which the species occupies, this varies from country to country, but all figures fall between 50 and 80%. It has been calculated that Big Leaf Mahogany only remains in 34% of its original range in South America (Martinez et al. 2008). It is therefore suspected that the population of this species globally has declined by at least 60% over the last three generations (180 years) and decline is continuing due to logging and conversion of habitat to human land uses, further reducing the possibility of regeneration. The species is assessed as Endangered.

Swietenia macrophylla has a wide native distribution. The species is native to Mexico, south through all countries in Mesoamerica into South America where it is found in Colombia, Venezuela, French Guiana, Ecuador, Peru, Bolivia and Brazil. The species origin and presence in Guyana needs confirmation.

The species has been introduced to Africa and Asia for cultivation, where it occurs in horticulture and in plantations (Lemmens 2005).

This species has experienced a historical population decline and is experiencing an ongoing decline. The extent of decline is variable from country to country where the species is found. The extent to which Big Leaf Mahogany has been systematically removed from its native forests is sometimes called 'mining'. It is considered unsustainable, and even where logging cycles and selective logging (controlled by diameter at breast height (DBH) size) are in place, these are often insufficient to allow for regeneration (Weaver and Sabido 1997, Grogan 2001, Kammesheidt et al. 2001, Grogan 2003).

The species began to be commercially harvested in the 16th century from Central America (Mejía et al. 2008). In the 20th century, as commercial tree stock of the species depleted in Central America, there was expansion of harvest and trade of Big Leaf Mahogany into South America (Mejía et al. 2008). This was also catalysed by the improvement to logging technology. Initial exploitation targeted subpopulations along rivers, down which the logs can then be transported (Mejía et al. 2008), but with the expansion of road networks, and progress in saw mill machinery in the second half of the 20th century, Big Leaf Mahogany could be targeted in new areas and further into forested areas. These changes encouraged an increased harvest of Big Leaf Mahogany from the wild, and production of mahogany products therefore also increased. By 2000, Big Leaf Mahogany had been commercially extirpated (eradication of subpopulations of commercial size) within an estimated 49% of its range in Peru, 79% of its range in Bolivia (Kometter et al. 2004), and 65% of its range in Brazil (Martinez et al. 2008). In Mexico, 76% of tropical forests where Big Leaf Mahogany occurs have been lost (Calvo and Rivera 2000). Martinez calculated that Big Leaf Mahogany only remained in 34% of its original range in South America (Martinez et al. 2008.

Targeted logging of Big Leaf Mahogany not only removes mature individuals of the species but also reduces the chance of regeneration, as the disturbance caused by logging is not the type needed by Big Leaf Mahogany for regeneration (Mejía et al. 2008). Big Leaf Mahogany has low pre-harvesting seedling volumes, therefore even with well-practised post-logging silviculture, regeneration is poor (Snook 1996, Gullison et al. 1996, Grogan et al. 2003, Grogan and Galvão 2006, Martinez et al. 2008). Additionally, logged over sites are often converted to pasture, or degraded further by fires or invasive species.

Consequently, it is not only harvesting for timber that is a threat, but ongoing habitat loss and forest conversion in both Central and South America contributing to population decline. An estimated 63% of forest in the range of Big Leaf Mahogany has been lost in Central America compared to 26% in South America (Mejía et al. 2008). In Peru, 4% of habitat has been lost, followed by Bolivia with 8% and Brazil with 24% (Mejía et al. 2008). This has led to fragmentation of the habitat and subpopulations across the remaining range.

The trade of the species is now internally controlled and monitored, through the listing of the species in CITES Appendix II. Countries where the species is harvested and traded have to set and follow quotas to prevent over-exploitation. Many countries also have national legislation (some even have moratoriums) to deter harvest and trade of the species, however, illegal logging and trade of the species still occurs. Therefore, there is still a continuing decline in population size due to illegal logging activities.

Given the national and global estimates of loss of the species in the wild, it is suspected that the population of this species has declined by at least 60% over the last three generations (180 years) and decline is continuing. It is thought that large trees still remain in areas not yet targeted or inaccessible for logging. There are areas where small trees still persist (Grogan et al. 2002) and therefore, with available information, population decline is not expected to exceed 80%.

Country Data (summarized from Martinez et al. 2008)

In Brazil, harvesting of Big Leaf Mahogany began in the 1930s. It rapidly accelerated in the 1970s as other sources of mahogany became less available. Since 2001, there has been an export ban which saw a fall in stock and harvest volume from previous years (Mejía et al. 2008). Most recent estimates give a landscape-scale density for the species, ranging from 0.014–1.18 trees >20 cm diameter per hectare. Areas of historically high density, such as Para and Rondônia, now have very few trees remaining, and subpopulations viable for commercial level harvest are only available in 35% of the overall range of Big Leaf Mahogany in Brazil (Mejía et al. 2008). More trees remain in inaccessible areas and sites at the furthest edges of the species' range in Brazil, but densities are still low.

In Bolivia, industrial exploitation began in the 1960s (Martinez et al. 2008), and the Bolivian subpopulations haves been declining since this time (Martinez et al. 2008). It is likely that 'commercial populations' of the species no longer persist in Bolivia (Martinez et al. 2008). There are still large trees remaining in as yet unlogged and protected forests (Martinez et al. 2008). However, in areas of exploitation (such as La Chonta and Lago Rey), the subpopulation structure shows decreasing density as size increases e.g. there are very few trees over 60 cm in DBH (Mejía et al. 2008).

In Colombia, decline of the species is acutely linked to colonization, with the country being a main supplier of mahogany to Spain during this time. There was high demand and extraction up until the beginning of the second world war (Martinez et al. 2008). In the 1950s, the US was a top exporter. Since then, there have been limited records of the species in Colombia and consequently trees available for commercial harvest are thought to have been totally extracted. It is estimated that 50% of Big Leaf Mahogany's historic range in Colombia has lost forest cover (Martinez et al. 2008).

In Ecuador, due to a number of factors, decline of Big Leaf Mahogany is limited in comparison to other countries in the region. This is due to low frequency of the species in the forests, late industrial logging activity in the 20th century and limited understanding of local names for the species. After the species was discovered, there has been commercial harvest of the species, to the extent that 73% of the historic range is now considered to lack 'commercial populations' (Martinez et al. 2008). Logging activity in Ecuador is illegal. The species can still be found along some rivers and in protected areas.

In Peru, harvesting began in the 1920s, with volumes harvested consistently increasing with mechanization and transfer of pressure from riverine subpopulations to inland localities (Martinez et al. 2008). Commercial intensification also occurred in Peru during the 1980s and 1990s as Big Leaf Mahogany tree stock in surrounding countries declined (Martinez et al. 2008). There was a particular peak in 2002 when 52,000 m³ of Big Leaf Mahogany was traded. Since the turn of the 21st century, volumes of Big Leaf Mahogany harvested and traded have decreased dramatically (Mejía et al. 2008). 'Commercial populations' are considered to be exhausted, with trees remaining in very few localities which are mostly inaccessible and in remote sites (Mejía et al. 2008). A study in 2008 suggested that 144,203 trees over 75 cm DBH and 82,296 trees less than 70 cm DBH remain in Peru (Mejía et al. 2008). Overall, in Peru the landscape-scale density ranges from 0.003 to 0.164 trees per hectare, with a 40/60 proportion for trees <75 cm and >75 cm diameter. Martinez et al. (2008) found that 51% of the range of the species has been lost in Peru.

In Venezuela, the range of Big Leaf Mahogany was calculated by Martinez et al. (2008) to have declined by 89% from its historical range. The species is found in low densities (Martinez et al. 2008). Original extraction occurred in areas surrounding new cities. Over extraction caused a decline in trade volumes from 23,764 m³ to 1,919 m³ from 1971 to 1999 (Martinez et al. 2008). The only remaining large Big Leaf Mahogany stands are thought to occur in protected areas.

In Mexico, the species is still abundant in the Yucatán Peninsula (Navarro-Martínez et al. 2018). However, historical decline occurred due to overharvest and deforestation. The species is found forming small groups, and responds well (in terms of regeneration and viability) in forests disturbed by hurricanes and fires. The species is managed sustainably and effectively in Mexico, with well implemented silvicultural techniques employed. There is some local extinction of the species in northern Quintana Roo and Yucatán due to threats to the habitat, which if they continue, could cause 60% decline of the species in the area (Navarro-Martínez et al. 2018). In other areas, such as protected areas or those managed by indigenous communities, densities of Big Leaf Mahogany can still be high with a greater number of trees in larger size classes being observed.

Elsewhere in Mesoamerica, very few large mature trees remain in Nicaragua (UNEP-WCMC 2010) and Panama (CoP8 Prop94 1992). In Costa Rica, wild native Big Leaf Mahogany trees or subpopulations are few, rare or very isolated; on the northern Pacific coast, Swietenia macrophylla and S. humilis are approximately sympatric. The species is naturally rare in Ecuador, Guatemala (CoP10 Prop69 1997). The remaining subpopulations in much of the species range are small, and often only protected by inaccessibility. Historically, mahogany wild subpopulations in Costa Rica were few and isolated; most mahogany seen in Costa Rica today is planted.

This large tree species can grow up to 60 m in height. The species grows in different types of dry and moist tropical forest up to 1,400 m asl (CoP8 Prop93 1992). In different parts of its range, it occupies lowland areas or more montane areas. It is found in sites which experience episodic flooding or in erosion gullies (CoP10 Prop69 1997). Growth in riverine, terre firme and on alluvial flats also occurs. The species persists on a range of soils, and in transition zones between different forest types. It is able to withstand much ecological disturbance such as flooding, hurricanes and fire. These events often stimulate growth as they reduce the canopy cover which enables, shade-tolerant seedlings to grow up (Mejía et al. 2008). The species has generalist pollinators and seed dispersal is of a short distance and via the wind (Mejía et al. 2008). The tree is relatively fast-growing but is long-lived, reaching reproductive maturity at 70–80 cm diameter at breast height (DBH) (Mejía et al. 2008).

The major threat to this species is over extraction for timber. The species has been harvested commercially for timber for four centuries. In the past century timber extraction has become unsustainable with many sources citing the species as commercially exhausted from some countries where it is found. The cause of this decline is for a number of reasons:

• a shift from extraction of Swietenia mahogani to S. macrophylla when the former became rarer in the wild (CoP8 Prop93 1992);
• the boom and bust harvest cycle of S. macrophylla across its range, beginning in Mexico and moving south through to South America (Mejía et al. 2008);
• inappropriate selective logging measures, which often removed the most mature trees, thus reducing the gene pool for future regeneration, decreasing seedling availability and reducing the regeneration of previously logged areas; additionally, logging cycles were too short to allow the species to regenerate effectively (Grogan et al. 2002);
• the advent of mechanization in the timber industry, meaning previously inaccessible localities could now be reached by road and targeted for extraction; saw mills and logging machinery became easier to use and establish, this meant fast cutting and processing times, along with increased ease of road transport to move logs (Mejía et al. 2008);
• there has been consistent demand for mahogany (including Big Leaf Mahogany) timber over the centuries; with growing economic wealth there is often pressure on more prized timber sources and its rarity can often increase the demand in particular markets; the value of the timber and sustained demand drives illegal logging (Martinez et al. 2008);
• a lack of resources to enforce protection policies;
• the difficulties to successfully and commercially grow the species in plantations also means that pressure remains on wild individuals (Paul and Weber 2012).

Expansion of the agricultural frontier is also a threat to the species, as well as a growing human population, leading to urban expansion and additional pressures on the habitat of the species.

This species is a prized and valuable timber species. Since the 16th century, it has been commercially exploited for timber which coincided with the Spanish colonization of South and Central America (Mejía et al. 2008). It is valued for its strength, workability, durability and colour. The timber is used to make high quality furniture, veneers, decorative and ornamental features and musical instruments (Mejía et al. 2008). Demand is greatest from countries such as the US, UK and China (Mejía et al. 2008).

The original commercial source of mahogany was Swietenia mahogani from the Caribbean, but as stocks of this species decreased there was a shift to heavier exploitation of S. macrophylla in the 20th century, particularly in South America. This exploitation of S. macrophylla only increased with mechanization and development of timber routes across South America (CoP8 Prop93 1992). Given the value of mahogany in general and Big Leaf Mahogany in particular on international markets, illegal logging and timber poaching of trees is continuing despite the protection of the species in National and International Law. For example, in the 2008 Non Detriment Findings it states that 'in 2005, 12.45% of the total volume of mahogany exported came from illegal logging, while 83% of companies exporting mahogany from Peru sold quantities originating from illegal logging'.

The species is listed in CITES Appendix II to limit and monitor international trade of the species. Despite this, illegal logging of the species does still occur, and there is illegal trade of the species too which may be up to 100 or 200% higher than reported in trade figures (UNEP WCMC 2010). Trade is from extraction from primary forests. A shift to other sources of rosewood, such as Khaya, has been noted, which suggests that the commercial supply of S. macrophylla is depleted in South America (UNEP WCMC 2010). Guatemala now exports mahogany to Mexico as their national tree stock has become depleted (Snook 1996).

Big Leaf Mahogany is found in plantations in South America and in many countries in Southeast Asia (including India, Sri Lanka, Bangladesh and Indonesia) (Krisnawati et al. 2011). However, the species does not grow well in plantations, with the greatest risk being from Hypsiplya grandella commonly known as Mahogany Shoot Borer (Newton et al. 1993). This pest limits the success of plantations by causing multiple shooting in juveniles, rather than a single straight trunk, the former of which is not profitable and undesirable for timber (Paul and Weber 2012). Once the pest is in the plantation, all trees are impacted (Paul and Weber 2012). Some success in mahogany plantations has been seen with intercropping of weeds and other plants (Paul and Weber 2012), inoculation, pesticide application, shade growing (Corenlius et al. 2004, Goulet et al. 2005) and there is also research into grafting as a possible solution. However, applications of these methods can still be damaging and can cause a lack of profitability in the plantations. More long term, well funded research is needed to find a viable solution and create plantations which can be used in the fight against wild extraction of the species (Hilje 2020). Plantations can also take a long time to establish, and upwards of 10 years is needed for a commercial log to be produced.

Locally, a third of Big Leaf Mahogany in Brazil is sold on the domestic market, at a lower price than its exported value (CoP10 Prop69 1997). In South America, Big Leaf Mahogany is used locally in construction due to its resistance to insect and fungal attack (Mejía et al. 2008). The bark and seeds may also be traditionally used as medicine for different ailments. Oil extracted from the bark can be used for cosmetics (Mejía et al. 2008).

International trade in timber of the species is subject to the provisions of Appendix II of CITES. The species was first listed in CITES Appendix III for Costa Rica in 1995 and five additional range states between 1998 and 2001. In 2003, Big Leaf Mahogany was transferred to Appendix II for all range states covering annotation #6 (logs, sawn wood, veneer sheets and plywood) (UNEP 2023). Export quotas have been granted to certain countries. Between 1997 and 2023 seven range states (Belize, Bolivia, Costa Rica, Ecuador, Honduras, Nicaragua, Peru) submitted annual CITES quotas to limit or cease exports of Swietenia macrophylla. In 2023, Panama suspended all trade of wildlife specimens (including S. macrophylla) harvested from the wild for commercial purposes (UNEP 2023).

There are also many national policies in effect to reduce the pressures on the species, although there is a limit to how well these laws have been enforced and the species remains illegally logged and traded (CoP8 Prop93 1992, CoP8 Prop94 1992, CoP10 Prop69 1997). For example:

1. export of the species has been banned in Venezuela since 2004;
2. there has been no international trade from Colombia between 1998 and 2008;
3. a five-year logging freeze from 1990 to in Bolivia, forest certification initiatives introduced with some success in 1997;
4. Brazil has set harvest quotas;
5. Ecuador banned the harvest of the species between 2007 and 2011.

Countries also have forestry management codes, such as harvestable diameters and guidelines on how many individual trees to take and leave for regeneration, but often these policies are poorly enforced and understood. They also do not reflect the ecological needs of the species. More needs to be done to develop effective protection policy for the species and to properly enforce these policies. Prosecution of those found to be involved in the illegal logging of these species is needed, particularly buyers and middlemen. Despite the occurrence of the species in protected areas, these are thought to be insufficient to maintain the genetic diversity of the species, as already the species is illegally felled within them and land is only 'protected on paper' (Snook 1996). The protection of the remaining localities of the species should be ensured. Further research is needed in terms of establishing ex situ collection and conservation nurseries for the species.

Studies should be conducted to investigate the success of plantations, and whether these have helped to relieve pressure on the species in the wild, or if there is potential for this to occur. This should be supported by additional research and development of best practise methodologies for growing the species in plantations and eradicating the Mahogany Shoot Borer. Information collated on the GlobalTree Portal finds the species is assessed as threatened in Bolivia, Brazil, Colombia, Guatemala, Peru (BGCI 2023).