Invasive species and fragile habitats in the Galápagos
The Galápagos Islands host a vibrant array of desserts and plant life, yet nonnative species like blackberry and guava have begun to spread rapidly. These invaders threaten endemic plants and upset the delicate balance of the archipelago’s ecosystems. Scientists and conservation teams use drones and field monitoring to track their expansion and guide management actions aimed at protecting native species.
Researchers seek to understand the approximate area covered by invasive plant stands and the effort required to manage them. They also explore whether certain plant communities support or hinder habitats essential to threatened animals. The goal is to build high-resolution maps that reveal where invasive species concentrate and how they might respond to control measures.
To achieve this, the project relies on very high resolution maps that show the distribution and abundance of invasive plants such as blackberry and guava, as well as other nonnative species like Cuban cedar and quinine. Satellite imagery and drone data are employed to map key plant species across the landscape.
These maps inform restoration planning for terrestrial ecosystems and contribute to the broader effort to safeguard the archipelago known as the Enchanted Islands.
The Scalesia forest decline
Scalesia is native to the Galápagos and comprises about fifteen species. Three of these can reach tree stature, growing up to fifteen meters, while some individuals in drier areas exist as smaller shrubs with an appealing fragrance. The Scalesia forests once covered more ground but now survive in limited pockets due to past agricultural use and ongoing invasive pressures.
The focus on Scalesia reflects its importance to the ecosystem. The canopies support a variety of life, including lichens, mosses, and numerous insects that sustain birds such as Darwin’s finches. Some insects rely exclusively on Scalesia, meaning the species’ loss could trigger cascading effects on dependent moths and other organisms.
Across higher elevations on Santa Cruz and neighboring islands, Scalesia forests persist in small pockets. Much of the former forest cover has disappeared due to agriculture and ongoing invasion by blackberry, leaving only about 3 percent of the original area.
To counter this decline, the Galápagos National Park Directorate is working to preserve these Scalesia stands on roughly 300 hectares of forest remnants scattered across the mountainous regions, in collaboration with local researchers and conservation teams.
Blackberry as a major threat
Experts describe blackberry as a severe challenge. A renowned researcher, with training from a leading European university and experience studying the archipelago, notes that blackberry has emerged as a dominant threat since its introduction around 1968. The thorny vine competes for space with Scalesia, casting dense shade and limiting the native plant’s ability to produce seeds.
Scalesia is not just a plant; it supports a web of life. Lichens and mosses grow on its branches, and insects present on Scalesia influence bird communities. Some insects depend on Scalesia specifically, so the loss of this genus could threaten coexisting species and alter the ecosystem’s balance.
Manual and technological control methods
Park rangers historically rely on hand clearing of blackberry followed by targeted herbicide application. This ongoing effort spans years and areas, with stubborn regrowth challenging even well-established control programs. Seed remnants on the ground and seed dispersal by animals contribute to the persistence and spread of blackberry across the terrain.
To enhance effectiveness, scientists explored machine learning approaches to map plant communities using aerial imagery from drones and satellites. While satellite images offer broad coverage and eight-color channels, including infrared, drone imagery provides higher resolution that better distinguishes plant species based on chlorophyll content.
Combining drone data with spectral information, researchers apply a statistical model to identify species and estimate their distribution. In humid zones such as Santa Cruz, Floreana, Isabela, and Santiago, a model named Random Forest analyzes color features to classify species and infer their abundance from satellite data. This approach documents changes in plant communities and helps explain how alien species threaten the distinctive biodiversity that inspired Darwin’s theories of evolution.
Ultimately, the work underscores how invasive plants jeopardize both flora and fauna on the island chain, where preserving native species remains a central conservation priority.