May 18, 2021

We are running out of coffee | Science

We are running out of coffee | Science

Most of the wild coffee species are in danger of disappearing in the coming decades. Of some there are only three or four plants left and others there is no news for almost a century. One of the threatened ones is the Coffea arabica, from which most of the cultivated varieties come. Although only three species have commercial interest today, the extinction of only one of the others threatens the future of both wild and cultivated coffee.

Almost 100% of 10 million tons of coffee beans that are going to harvest this season are arabica or robusta (Coffea robust). There is a third species (Coffea liberica) that is consumed in various parts of Africa, but its main value in the cultivation of coffee is as a graft in the rhizome of the other two species. In nature, however, there is much more coffee. As far as is known, there are at least 124 wild species of Coffea. And most are not from the humid lands of Ethiopia. There are in Sierra Leone, in the western end of the African continent, even in the state of Queensland, east of Australia.

Now, researchers from Royal Botanic Garden of Kew (United Kingdom) have determined the status of all known wild coffee species. The results, supported by a decade of expeditions in the field, have just been published in Science Advances. Of the 124 species, 75 are threatened (60%), according to the criteria established by the Red List International Union for the Conservation of Nature (IUCN).

"Among the threatened species of extinction are those with potential to be used in the cultivation and development of the coffees of the future"

Aaron Davis, Royal Kew Botanic Garden

The percentage of threatened increases up to 70% if the almost twenty species of species for which there is no reliable data are deducted from the total. Of 14 there is no recent information, largely due to the wars that have prevented its study. Of some, for more than a century of which there is no news and of five, all Asian, there is only evidence in western herbaria. Of the total, 13 are in critical danger of extinction and only 35 have been classified as not threatened. Although the risk occurs throughout the geographical distribution of wild coffee, the drama is concentrated in Madagascar, with 43 threatened species, Tanzania with 12, and Cameroon with seven.

"Among the threatened species of extinction are those with potential to be used in the cultivation and development of the coffees of the future," says the head of the coffee research in Kew principal author of the study, Aaron Davis. It is not just that saving a species of disappearance is a value in itself, is that, even without commercial interest today, many of them can provide resistance to diseases or be able to face the increasingly complicated weather conditions . "The use and development of the resources of wild coffee could be decisive for the long-term sustainability of coffee," adds Davis.

The authors of the study classified all the species into three groups according to their current and foreseeable future relevance for the commercial cultivation of coffee. In a first group they placed the wild relatives of arabica, the robusta and the liberica, in addition to the Coffea eugenioides, an ancestor of the first. Their genetic closeness to commercial species makes them vital reserves for the renewal of their gene pool. In a second group they included 38 species that, although they do not hybridize naturally with commercial ones, could bring improvements in resistance, aromas, yield … through modern agronomic techniques. In the last group there are 82 species without commercial interest now, although they could be exploitable thanks to genetic engineering.

The main threatened species, of the first group, is Arabica, on which the cultivation of coffee is based. Of the second group, there are 23 other species in danger. And of the rest, other 51 species. To understand the scope of these figures and percentages, they can be compared with the general state of conservation of the plants. While in the whole plant kingdom, only 22% of the species are threatened, almost three out of four coffee makers are.

Among the causes there is a natural and the rest of human origin. The first is the biological rigidity of coffee itself. Although the commercial varieties are present in all the tropical regions of the planet, most of the wild species occur in narrow and localized geographic bands, very adapted to the local conditions. Therefore, human disturbances such as the loss of habitat, the advance of agriculture or the effects of climate change, such as the reduction of the rainy season and the increase of hot days, are affecting the resilience of wild coffee plantations.

"In coffee, the issue is critical: there are only two species that are used commercially and only a small part of the genetic variability is used," recalls the director of the National Coffee Research Center of Colombia (Cenicafe), Álvaro León Gaitán, not related to this study. "The problem is that as far as the cultivation conditions change, it is up to changing the plants and the little genetic diversity used in the commercial varieties does not give to select new types of plants," he adds. Hence the importance of wild species, which may have genes with answers to these problems. "However, in the case of Arabica, the natural forests of Ethiopia and South Sudan where the species originated have been degraded, so the collections of germplasm that were collected in the 1960s must be used," he adds. responsible for Cenicafe.

Although there are only three species with commercial interest, in nature there are more than a hundred species of coffee

But the problem of conservation on-site it gets worse because many of the wild species do not have backups outside. Much of the plant (and animal) biodiversity has conservation strategies ex situ. Whether nineteenth-century botanic gardens, herbaria or seeds or germplasm banks, resources of most plants of interest to humans are stored in various parts of the planet. Here, while 71% of the 63 main human crops have some backup, only one third of the coffee species have it.

"Unlike bean or corn, the viability of coffee seeds is significantly reduced if they are dried and frozen (the embryo dies)," the researcher recalls. Global Crop Diversity Trust, Nora Castañeda, author of that study with the 63 main crops. "Therefore, it is necessary to have other alternatives for the conservation of these genetic resources, such as field germplasm banks, in vitro cultures, cryopreservation, natural parks and even on the farms of the producers," adds the Colombian scientist. The objective of this international organization, based in Bonn (Germany), is to preserve crop diversity to protect world food security.

For Castañeda, the results of the study (in which he has not intervened) are a reflection of the state of vulnerability of wildlife on the planet in general. "However, it is surprising that the relatives of coffee are within the group of plants with higher risk of extinction and, moreover, are vulnerable because they lack concrete actions for their conservation," he says in an email. In 2017, in collaboration with World Coffee Research, his organization published a global strategy for coffee conservation. They estimated that it would take just one million dollars (880,000 euros) to "conserve in perpetuity genetic resources of coffee that are currently in key collections," said the Colombian scientist.


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