By: Anna Calle-Loor
MESM Anna Calle-Loor has nearly five years of experience working in ecological restoration and biodiversity conservation in the Galapagos Islands. She is a former researcher for the Galapagos Verde 2050 (GV2050) Program of the Charles Darwin Foundation (CDF). She is also a member of the Galapagos’ Plants Specialists Group of the IUCN’s Species Survival Commission and the Society for Ecological Restoration. annagcalle@gmail.com
The Galapagos archipelago is famous for inspiring Charles Darwin’s theory of evolution by natural selection after his visit in 1835. Its geographic and environmental characteristics have given rise to unique creatures like giant tortoises, pink iguanas, the second smallest penguins in the world, flightless cormorants, and the only marine iguana. Due to its extraordinary biodiversity, it was established as Ecuador’s first national park in 1959 and declared a UNESCO World Heritage Site in 1979.
Today, the islands’ biodiversity and volcanic landscapes continue to astonish visitors. But behind their reputation as a pristine paradise lies a story of vulnerability, degradation, and a need for ecological restoration.
Islands: Biodiversity Hotspots and Extinction Hotspots
Islands often have high levels of endemic species, but they are also highly vulnerable to extinctions. With small populations, restricted geographical ranges, and often having evolved with no predators, many island species are especially sensitive to disturbances.
We have seen the consequences before. On Easter Island, deforestation and overexploitation of limited resources led to ecological collapse and the downfall of a once-thriving society. Mauritius Island lost the dodo, one of the first species recognized as extinct due to human activity, in the 1600s. Hawaii has earned the unfortunate title of “the extinction capital of the world” because of its high extinction rates of plants, insects, and birds. Guam has lost most of its native birds following the introduction of the invasive brown tree snake. All of these are reminders of how quickly biodiversity can disappear when island ecosystems are disrupted.
The Galapagos are no exception. With ecosystems that have already suffered degradation, efforts now go beyond species conservation to include ecological restoration.
A History of Degradation
With a recorded human history that starts in 1535 with the arrival of the bishop Tomás de Berlanga, there have been many people that have visited the islands and inevitably have left a mark on them. The first visitors were pirates, whalers, prisoners, and a few early settlers. But they did not come alone. They brought rats, cats, goats, and other animals, many of which became invasive and highly destructive. To give you a scale of the problem, an eradication campaign known as Isabela Project was launched in 1997 and eliminated >140K goats from three islands.
Today, the pressure continues. Around 30,000 people live in the Galápagos, and nearly 300,000 tourists visit every year. Of course, this level of human activity requires infrastructure. The islands now have roads, towns, gravel mines, agricultural fields, and landfills, all of which exert pressure on the surrounding environment. The continuous flow of tourists and imported goods make introduced species a growing threat.
In response, the Galápagos National Park Directorate and conservation NGOs like the CDF have launched multiple ecological restoration projects. I have collaborated in several of these efforts through the GV2050 Program, combining endangered species recovery with ecological restoration strategies.
Recovering Galapagos Endangered Flora
About 60% of Galapagos flora is threatened with extinction. This includes Lecocarpus lecocarpoides, a shrub with yellow daisy flowers that is found only on Española Island and a few nearby islets. Unfortunately, it has almost disappeared from the main island, with a single population left, likely due to past goat herbivory. Although goats were eradicated from Española in the 1970s, L. lecocarpoides has not recovered.
That led us to investigate deeper into its biology. Were the remaining plants producing viable seeds? A study found that yes, there was a large number of seeds in the soil and 80% were viable. Then, why did we rarely see any germination? There was something preventing the seeds from germinating, and the same study hinted at the thick outer seed coat.
In our laboratory, we found that using a scarification technique consisting of carefully cutting the seeds under a stereoscope leads to high germination rates of 75%. As part of the investigation, we returned 29 adult plants to Española and produced over 6000 seeds to continue restoration efforts. These were promising results, but they also led to more questions.
How does the scarification process happen in nature? The interactions with other species might play a key role. We have seen moth larvae feeding on the seed coat without damaging the embryo. And we suspect Darwin’s finches might also be involved. They feed on the hard and spiny seeds of Tribulus, which are very similar to Lecocarpus seeds. Could they be helping L. lecocarpoides germinate? This remains to be investigated.
Restoration of Arid Ecosystems
The first island most visitors arrive to in the Galapagos is Baltra Island, where the main airport is located. But few realize it is one of the most degraded islands in the archipelago. A combination of invasive especies and the construction of a U.S. military base during World War II led to habitat destruction and likely to the local extinction of land iguanas, the main seed dispersers. Although they have since been successfully reintroduced through a successful captive breeding program, much of the vegetation has not recovered.
A challenge when restoring an ecosystem that has been significantly altered, especially when historical records are scarce, is defining what restoration should aim to achieve. To help answer that, we compared Baltra with its neighbor island, North Seymour, which shares similar ecological conditions but has suffered less degradation.
Through two vegetation surveys we identified the plant composition and community structure that once likely existed on Baltra. For example, we found that the five most dominant woody and cacti species in North Seymour are Bursera graveolens, Castela galapageia, Cordia lutea, Opuntia echios, and Parkinsonia aculeata. The surveys also showed that Baltra’s most intact vegetation remains in the north and southwest, while the central region is sparsely vegetated.
These results can serve as guides for future restoration efforts. For example, for choosing what species to plant and where to plant them. On Baltra, where infrastructure like the airport, roads, and Ecuadorian military base already shape the landscape, restoration should minimize potential conflicts with these other land uses. Instead of trying to recreate the past, efforts should aim to increase connectivity between the two remaining patches of native vegetation to support wildlife movement and seed dispersal.
Recovering Keystone Species: The Opuntia Genus
If there is one Galapagos plant that is underrated, is the Opuntia prickly pear cactus. These cacti are a food source for two of the most charismatic animals of the Galapagos, giant tortoises and land iguanas. They also provide native birds with food, shelter, and nesting structures, including Darwin finches and Galapagos mockingbirds, two groups of birds that inspired Darwin’s theory of evolution by natural selection.
Additionally, they are one of the best examples of plant adaptive radiation in the Galapagos. Their 14 endemic taxa show great variation in form and size, with up to 4-fold differences in height and 100-fold in seed size. Some grow as tall as 12 meters, about the height of a pine tree! Interestingly, tree-like forms are found on islands with giant tortoises, while shorter forms occur where tortoises are absent.
Unfortunately, populations have declined in some islands and low regeneration is a pattern throughout the archipelago. This is exacerbated by the pressure from introduced and native herbivores.
Because of its ecological importance, Opuntia was included in a restoration plan for four islands. Among the actions proposed for increasing its numbers is testing different propagation methods: planting seedlings, cactus pads, seeds from fresh fruits, and perhaps most intriguingly, seeds collected from tortoise and iguana droppings. There is evidence that passing through the digestive system of these animals helps scarify the seeds, improving germination.*
But giant tortoises and land iguanas are not the only species that seem to be helping Opuntia regenerate. We have observed Opuntia growing underneath the protection of trees and spiny shrubs. Could they be shielding them from herbivores or ameliorating harsh environmental conditions? The answer remains unknown, as there have been no formal studies on plant-plant facilitation in the Galapagos. This presents a unique opportunity to deepen our understanding of plant facilitation in island ecosystems and how these interactions can be used to improve restoration outcomes.
Left: Giant tortoise feeding on a broken branch of Opuntia cactus. Photo credit: Anna Calle-Loor.
Right: Cactus finch feeding on the pollen of an Opuntia flower. Photo credit: Elena Espín.
From Evolution to Restoration
The Galapagos changed our understanding of how new species emerge. Now, they are challenging us to learn how to repair the ecosystems that sustain those unique species. This extraordinary archipelago is no longer just a living laboratory for evolution. It’s becoming a living laboratory for restoration ecology. And if we get it right, the Galápagos can once again inspire the world, this time by showing what successful ecological restoration can look like, not just here, but everywhere.
* Estupiñán, S., & Mauchamp, A. (1995). Interacción planta–animal en la dispersión de Opuntia de Galápagos. Charles Darwin Foundation, Puerto Ayora.
