Is the palo santo tree (Bursera graveolens NOT Bulnesia sarmientoi) endangered?
I get asked this question a lot (gosh I wonder why!?), and I think up to this point I haven't really given a satisfactory answer. So here it is: my FULL, hopefully satisfactory, answer. But you'll have to be ok with a bit of nuance and some reading...
But first, which palo santo are we talking about?
Apparently there has been a lot of confusion in the health and wellness world about palo santo because there are two different species of trees that share the same common name: Bursera graveolens (our palo santo) and Bulnesia sarmientoi (the other, very clearly endangered, palo santo). First of all, these two species' ranges don't even overlap. Like they don't even have a single country in common! Our palo santo grows in tropical dry forest habitat in Mexico, Central America (except for Belize and Panama), and northern South America (Colombia, Venezuela, Ecuador [including the Galapagos Islands], and Peru), and the other palo santo grows in Argentina, Paraguay, Brazil, and Bolivia. Here is my working map showing the range of our palo santo, Bursera graveolens:
Secondly, the two species are pretty distantly related. For a little window into a biologist's brain: we tend to think not just in terms of scientific names, but in terms of the evolutionary relationships between the named species. The two palo santo species are not even in the same plant order, a classification level higher than family, meaning they are pretty distantly related (see this article for some evolutionary trees showing their hypothesized relationship). Bursera graveolens is in the Order Sapindales, and Bulnesia sarmientoi is in the Order Zygophyllales. This is why I wish we only ever used the scientific name for plants (but I suspect that is not going to be a popular idea!).
The REAL Question
Ok, now that we've cleared up the common name situation ... I think what people are really asking me when they ask if palo santo is endangered is whether the palo santo products they purchase are hurting wild populations. As far as I can tell, all the products for sale are from Bursera graveolens, not from Bulnesia sarmientoi, but of course it's possible that someone out there is smuggling Bulnesia into the United States, so make sure you research which species your products come from. If you are confident you are buying Bursera graveolens from a sustainably produced source (more about that in a minute), then you are not hurting wild populations of palo santo. In fact, you may be helping to conserve palo santo and its habitat by purchasing sustainably produced forest products (see my lab note on the products I bought from Mangamanguilla). Products like this provide local communities with an economic incentive to conserve the forest rather than simply cutting trees down and selling them for timber.
Sustainable producers of palo santo products never even cut a single living tree down. They only harvest the wood from dead, fallen trees. I have to admit I was really skeptical that there could be enough dead, fallen trees in a forest to make a business selling wood or jewelry possible. And then I visited a healthy tropical dry forest (the habitat of palo santo) in the Área Conservación Privada Mangamanguilla in Piura, Peru. Palo santo is a dominant tree species in Mangamanguilla's forest, and fallen branches and trees were common. Read my lab note about this truly remarkable community in rural Peru that managed to conserve 1700 hectares of critically endangered dry forest habitat.
But are there unsustainable sources of palo santo sold on the international market?
As a scientist I really struggle with the question of whether some of the palo santo sold on the international market is from unsustainable sources (i.e. from live cut trees) because I don't have any data to adequately answer this to the level that a scientific journal would publish. This question is pretty far outside my area of research (evolution and conservation genetics), and although it is a very worthy question that absolutely needs to be answered, I am not going to be answering it before I finish my PhD.
But can we just talk logically here? I've done google searches and there is page after page of hits for companies selling palo santo (Bursera graveolens) wood products. Dozens of vendors on amazon. I mean, you can buy palo santo at Walmart.com! So yes, I think logically there is either: a) a lot of fake palo santo or b) at least some portion of the international market with questionable sources of palo santo (i.e. from live cut trees harvested from wild populations). If you're wondering whether anyone grows it for sale on the international market, I did hear some rumblings about this when I was in Peru in March 2019, but I don't think there are any large scale plantations growing it yet (it is grown for reforestation, though, which I'll be talking about in another lab note).
My advice if you want to buy palo santo wood products: get to know the companies you are buying your products from, and ask them about their sources. I have gotten to know a few of the companies selling palo santo and they have thoroughly vetted their suppliers. As in, they have traveled to Ecuador and Peru and gone to the forests where it is being collected and checked it all out for themselves. If your suppliers haven't done this or don't provide you with answers when you ask more about their sources, I would find a source that can. In the future I hope to see an independent sustainable source rating system like the one used for bird-friendly coffee.
Ok, but you haven't told me whether palo santo is endangered!!!!
The short answer is that due to massive habitat loss, coupled with local over harvesting in Ecuador and Peru, palo santo populations have declined in many areas. Palo santo is certainly not on the brink of extinction and is quite common in some of the tropical dry forests I visited in Mexico and Peru (I'll let you know about Colombia in a few weeks!). And palo santo, at least as it is currently described, has a very wide range, which means it isn't likely to become completely extinct (but remember, I might describe new species, which could have very narrow ranges). However, based on what I saw in Peru and Mexico, local extinction in many areas is a very real possibility. I should add that the government of Peru lists palo santo as an endangered species, but an assessment for the IUCN red list has not been done.
Loss of Tropical Dry Forest Habitat
The biggest problem for palo santo is that it only grows in the tropical dry forest, a biome dubbed the most endangered tropical biome. (I bet you thought it was the rainforest, didn't you?!). So what makes this biome so endangered? Compared to the rainforest, dry forest is a much more hospitable place to live, with more fertile soil, so people have settled in and farmed the dry forest over the past several thousand years. This conversion of land for cattle ranching and agriculture and human development has led to massive habitat loss. Only about 10% of the dry forest biome remains in many areas of Latin America, and in some areas it is much less than this. In Peru the situation for tropical dry forest is quite grim: an article back in 2010 found that less than 5% of the original extent of dry forest in Peru remains intact. The dry forest in Veracruz, Mexico, basically only exists as tiny fragments, with almost none of it under protection. However, in another lab note I'll introduce you to Aurelio Molina, an amazing birder and conservationist that owns Reserva Natural Xocotitla, one of the few protected dry forests in Veracruz.
Local over harvesting, sometimes not for what you think!
Palo santo has been used by people, particularly in Ecuador and Peru, for thousands of years for traditional medicine, mosquito repellant, and spiritual cleansing rituals. Local people will often go out into the forest and cut live trees down to sell at the local market. I would absolutely love to know how much local vs. international harvest is contributing to population declines. Hopefully my collaborator in Ecuador and I will work on answering this question when I go there in February 2020!
When I collected palo santo in Northwest Peru back in March and April 2019 with the intrepid botanist, Paolo Villegas, we had a very difficult time finding it in some areas of the Piura region.
We drove around one day for hours, stopping and asking everyone we saw where we could find palo santo. After convincing a few local people we met that we were in fact a couple of crazy botanists that just wanted to collect some leaves of palo santo, someone led us to a small population.
After this experience, I talked to Miguel Puescas Chully, my collaborator in Tumbes, Peru, and an expert on conservation and reforestation of dry forest trees, and asked him what was going on in Piura. His answer really surprised me.
People in Piura are cutting down palo santo trees to make FRUIT PACKING BOXES! I had only seen this use referenced in one really obscure publication and thought "huh, that's odd", and dismissed it as unimportant. But, according to Dr. Puescas, in the towns of Sullana, Chulucanas, and Tambo Grande, at least 10 trees/hectare/year are cut down to make boxes for packing fruit, particularly for lemons and mangoes. Dr. Puescas explained to me that illegal sawmills purchase the wood from individuals who go out into the forest and illegally extract palo santo trees. These illegal sawmills produce the boxes, which are then bought, presumably, by the agricultural companies in the area. Apparently fruit packers prefer them due to their aromatic essential oils, which repel insects and impart a nice scent to the fruit.
Conclusion
I hope this post answered at least some of your questions about palo santo's conservation status. More importantly, I hope it communicated the complex conservation issues that palo santo, and many tropical dry forest species, face. There is so much that we don't know, and yet every day we lose more tropical dry forest. I hope to make a little bit of difference where I can.
3 comments