Botany in the Azores

So … I skipped yesterday’s new species. It isn’t because there weren’t any new species that day (there were), but because I was studying for exams and, irresponsibly, didn’t leave enough time to write about ghost shrimp or African mice.

Aichryson laxum from La Palma in the Canary Islands. Photo by Frank Vincentz, licensed under CC BY-SA 3.0.

Aichryson laxum from La Palma in the Canary Islands. Photo by Frank Vincentz, licensed under CC BY-SA 3.0.

Succulents, plants that retain water in thick, fleshy parts, are amazing. The most familiar are the cacti, and you may recall a few weeks ago I wrote about the discovery of a new species of Mexican cactus, a prickly pear. Aloes are also familiar succulents, but there are many more, including today’s new species, Aichryson santamariensis (Moura et al. 2015).

Aichryson species have thick, fleshy leaves that hold lots of water. This is important because, like most succulents, they tend to live in dry habitats where rain can be both scarce and highly seasonal. Our new species hails from the island of Santa Maria in the northeast Atlantic, and appears to live nowhere else. All Aichryson have narrow ranges, with most found on the Canary Islands and just a few from mainland Portugal and Morocco.

Santa Maria is one of the Azores, a series of islands off the coast of Portugal. The Azores are popular tourist destinations but, like most small-island archipelagos, their recent biological history is not a very happy one. Invasive plant species, including mock-orange (Pittosporum undulatum) and Australian blackwood (Acacia melanoxylon) have wreaked havoc on native plants. Most of the native trees are declining rapidly, and the fates of smaller plants such as succulents may be soon to follow (Triantis et al. 2010).

Aichryson laxum, from La Palma, one of the Canary Islands. Photo by Tigerente, licensed under CC BY-SA 3.0.

Aichryson laxum from La Palma. Photo by Tigerente, licensed under CC BY-SA 3.0.

The problem is compounded by habitat loss. As much as 95% of the islands’ original laurel forest was cleared to make way for agriculture, resulting in the extinction of many plants that could not live anywhere else. In more recent years, when the economy took a bad turn and islanders started to leave for the more promising mainland, much of this farmland was abandoned. Now the vacant fields serve as habitat for invasive species, which are quick to take advantage of the disturbed land and heavy sunlight.

Three species of birds are known only from the Azores: Monteiro’s storm petrel, the Azores bullfinch, and the São Miguel scops owl. The storm petrel is considered vulnerable, the bullfinch is endangered, and the owl was not even discovered until long after it went extinct due to habitat destruction (Rando et al. 2013). Today the only São Miguel scops owls are dead, stuffed, and locked away in museum collections.

Azores islands. Photo by Guillaume Baviere, licensed under CC BY 2.0.

Some of the Azores islands. Photo by Guillaume Baviere, licensed under CC BY 2.0.

There is a phenomenon in conservation biology known as extinction debt. The idea is that after a disturbance (e.g., losing 95% of forest) there is typically a lag in the time it takes for most species to go extinct. To study extinction debt, researchers studied historical changes in insect biodiversity on one of the Azores, Graciosa Island (Triantis et al. 2010). This allowed them to make predictions about how many species the island is likely to lose if current patterns do not change.

The upshot: more than half of all insect species on the Azores may go extinct if nothing is done to restore the habitat that was destroyed. Whether this holds true for plants is unclear, but if more habitat is not protected, Santa Maria’s Aichryson could easily go the way of the scops owl, the only remaining specimens dried and curated in a museum.

Cited:

Moura M., M.A. Carine, and M.M. de Sequiera. 2015. Aichryson santamariensis (Crassulaceae): a new species endemic to Santa Maria in the Azores. Phytotaxa 234(1): 37–50

Rando J.C., J.A. Alcover, S.L. Olson, and H. Pieper. 2013. A new species of extinct scops owl (Aves: Strigiformes: Strigidae:Otus) from São Miguel Island (Azores Archipelago), North Atlantic Ocean. Zootaxa 3647(2): 343–357.

Triantis K.A., P.A.V. Borges, R.J. Ladle, J. Hortal, P. Cardoso, C. Gaspar, F. Dinis, E. Mendonça, L.M.A. Silveira, R. Gabriel, C. Melo, A.M.C. Santos, I.R. Amorim, S.P. Ribeiro, A.R.M. Serrano, J.A. Quartau, and R.J. Whittaker. 2010. Extinction debt on oceanic islands. Ecography 33: 285–294.

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One Response to Botany in the Azores

  1. Interesting to read about extinction debt. No one seems to worry too much about the insects and declines seem to be setting in fast.

    Like

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