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Guaiacum sanctum 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Zygophyllales Zygophyllaceae

Scientific Name: Guaiacum sanctum L.
Common Name(s):
English Holywood Lignum Vitae
Spanish Guayacán, Guayacán Real

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2017
Date Assessed: 2016-08-26
Assessor(s): Rivers, M.C.
Reviewer(s): Oldfield, S. & Leaman, D.J.
Contributor(s): López-Toledo, L. & Burslem, D.
Justification:
Guaiacum sanctum is a large tree found in Central America, the Caribbean and Florida, USA. The species has its widest range within Mexico and overall species range is estimated to exceed 100,000 km2. Its timber is highly valued and the species has been logged and traded for a long period. It is now listed under CITES Appendix II and trade of the species has significantly declined in recent years. The species is threatened by habitat loss, deforestation and fragmentation across its range. A four year study by López‐Toledo et al. (2011) estimated that the population to be greater than 10,000 mature individuals considering the species' uneven distribution ranging from 1,200 individuals ha-1 to 10 individuals ha-1. The species is found within protected areas and ex situ collection and recently a management plan has been ratified within Mexico. The species also exhibits good regeneration potential. Guaiacum sanctum is assessed here as Near Threatened, on the basis of the López‐Toledo et al. study in which the population decline in Mexico was measured as 28% over 24 years and within three generations of the species. It therefore nearly reaches the 30% threshold for Vulnerable A2c. There remains the need for investigation into sustainable use of the species and further identification of sites of protection.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Known from most of the Caribbean islands, in Central America including Mexico and Florida where remaining subpopulations are confined to restricted areas (CITES 2000). The species is most widespread within Mexico where it is found within nine states (Villaseñor 2016). The species is found up to 350 m asl. It is estimated that 131,087 km of the species native range remains in North and Central America (López-Toledo et al. 2008).
Countries occurrence:
Native:
Bahamas; Costa Rica; Cuba; Dominican Republic; Guatemala; Haiti; Honduras; Mexico (Campeche, Chiapas, Michoacán, Nayarit, Oaxaca, Quintana Roo, Tabasco, Veracruz, Yucatán); Nicaragua; Panama; Puerto Rico; United States (Florida)
Possibly extinct:
El Salvador
Additional data:
Upper elevation limit (metres):350
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The species is very slow-growing with an the estimated longevity of over 500 years (López‐Toledo et al. 2011) and an estimated generation length of 100 years. A four year study by López‐Toledo et al. (2011) estimated population decline to be 28.2 % within Mexico calculated as loss in area of occupancy (AOO) over three generations. Decline is not consistent across the species range and varies within country and even varies between regions within Mexico (López‐Toledo et al. 2008). Within Mexico, López‐Toledo et al. (2011) showed Yucatan and Chiapas to have the greatest extent of habitat decline and predicted that if current rates of deforestation continue there will be only 69,456 km2 and 122,085 km2 of habitat remaining by 2020 across all states. However, López-Toledo et al. (2008) showed a growth rate of >1.0 for three population in logged areas but overall population is in decline. The species has a patchy, uneven distribution. For example 1200 individuals ha-1 in Central Capeche to <10 individuals ha-1 in Chiapas (López-Toledo et al. 2008). Even so the population size is estimated to more than 10,000 mature individuals (López‐Toledo et al. 2011), based on a conservative estimate of 130 individuals ha-1 across the species range. Seedling density is also variable, with lower densities being found on the limits of the species Mexican distribution but up to 15,000 seedling being present in the species central, undisturbed range (López-Toledo et al. 2008). The forest the species G. sanctum occurs within is increasingly fragmented (López-Toledo et al. 2008). Despite this good genetic diversity seems to be currently retained within the population and subpopulations are still able to interbreed, reducing the risk of inbreeding depression (Oyama et al. 2016). There was only evidence for one bottleneck in the state of Campeche (Oyama et al. 2016).
Current Population Trend:Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Guaiacum sanctum is an evergreen tree that grows up to 5 m in dry forests, but it can be higher than 20 m in moist forest. It grows near the coast and at lower elevations inland, in tropical dry, semi-dry and moist forests, in woodlands, thickets and pastures, on hillsides and plains (CITES 2000). The species is slow growing, shade tolerant and able to regenerate after logging (López-Toledo et al. 2008). Fruiting begins between the ages of 30 and 70 years and is set between May-June or August-September, following flowering the previous months. Guaciacum sanctum trees are thought to be pollinated by insects and seed is known to be dispersed by mammals over longer distances, contributing to sustained genetic diversity (Oyama et al. 2016). The species habitat is vulnerable to deforestation for agricultural and urban expansion.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):100

Use and Trade [top]

Use and Trade: The species is used for its medicinal resin which is of commercial value and has been traded for several centuries. The medicinal uses of G. sanctum started nearly five centuries ago, as it was thought to be a cure for syphilis. It is still used  for a variety of purposes including: laxative, an antidote for poison, to improve the appetite, as a remedy for gonorrhea, syphilis, coughs, tuberculosis and to treat gout and rheumatism. Guaiacum sanctum is also a commercially valuable timber however its use as a timber has reduced recently. The wood was important in ship construction and within Mexico the height of industrial extraction was between 1990 and 1960, driven by trade to Europe, Asia and North America. On average 3,000 tons was harvested a year; luckily this trade has significantly declined and between 1987 and 1998 on average only 117 tons was traded a year (López-Toledo et al. 2008). This timber is being replaced by plastic (López-Toledo et al. 2008). The species can also be sold and planted as an ornamental tree.

Threats [top]

Major Threat(s): In Central America and Florida remaining populations are threatened with habitat loss or exploitation, e.g., in Guancaste in Costa Rica, El Salvador, Florida Keys. As with G. officinale, both the timber and medicinal resin are of commercial use and have been traded for several centuries. Tropical semi-deciduous and dry forests, which represent the main habitats of Guaiacum sanctum are among the most threatened ecosystems in the Americas and globally (Miles et al. 2006). Habitat loss of G. sanctum is mainly due to deforestation associated with increasing human populations, conversion of forest to human-managed areas, and increasing fragmentation of the remaining forest area (López‐Toledo et al. 2011, Miles et al. 2006). For Mexico, analyses of the geographic distribution suggested that their habitat is highly fragmented. It is likely that small, isolated populations close to the margins of the species’ distributions are likely to be particularly vulnerable to the negative demographic and genetic effects of forest fragmentation. Although, it still exists an international trade, this has diminished noticeably. At the moment, Mexico is the only exporter of Guaiacum sanctum timber and it is only logged at Campeche state in the Yucatan Peninsula at two localities. These two forest communities fulfill with CITES requirements. The species is used locally for timber but at low levels and this is not a long term threat to the species (López-Toledo et al. 2008). The illegal trade of this species is also rare, with only a small amount being confiscated from Yucatan in 2008. Hence, logging and over harvesting is currently considered a low threat to the species.

Conservation Actions [top]

Conservation Actions: The species is listed in Appendix II of CITES. Initially only timber was designated for control, but now the control includes all parts and derivatives (with some exceptions) (Oldfield 2005). In Guatemala, G. sanctum is assessed as Vulnerable, in Costa Rica and United States it is considered Endangered or nearly extinct. However in Cuba the species is considered abundant. Within Mexico the species is considered Endangered (López-Toledo et al. 2011). About 13% of the distribution of G. sanctum are covered by existing protected areas, this includes at least 10 sites within Mexico (López-Toledo et al. 2011). Within Mexico a species management plan was introduced in 2009. It includes i) sustainable logging of the species and selective logging of commercial trees >37.5 cm dbh. ii) reduced environmental impact to trees remaining in the forest, soil, flora and fauna. iii) restoration induced regeneration to combat negative effects of harvesting and iv) monitoring of demography and population dynamics. Restoration will include the collection and sowing of local seed (López-Toledo et al. 2008). It is essential that new sites of conservation are identified especially where the threat of logging and deforestation (e.g. Chiapas) are greatest (López-Toledo et al. 2011). Within Costa Rica, Fuchs et al. (2013) found populations within Palo Verde National Partk to be expanding. Further management of the species harvest across its range is required and the production of regional red list assessments is encouraged. The impact of habitat loss and fragmentation on population and genetic diversity should be further quantified. There are several known ex situ collections in arboreta and botanic gardens worldwide (BGCI 2016).

Citation: Rivers, M.C. 2017. Guaiacum sanctum. The IUCN Red List of Threatened Species 2017: e.T32955A68085952. . Downloaded on 22 September 2018.
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