Beauty or Burden: The Ecology of Angel Island

By Tim Smith ’26

Last spring, I had the opportunity to study abroad with the School for International Training (SIT) in their Climate Change program. During this experience, I witnessed firsthand the complexities governments face when tackling conservation work. One unfortunate reality about “going green” is that there isn’t always a perfect or universally “good” solution. Still, even imperfect solutions can reduce environmental burdens or extend the longevity of ecosystems—if we choose to implement them.

One of the first examples we encountered that semester was on Angel Island, where there’s an ongoing debate about the presence of blue-gum eucalyptus trees and whether they help or harm the ecosystem.

Angel Island was one of our first excursions, and it was a beautiful introduction. Located in the heart of the San Francisco Bay, the island is visible from downtown and the Golden Gate Bridge. The lack of buildings makes it feel untouched—especially in contrast to the endless stretches of houses and skyscrapers on the mainland.

Once on the island, we were greeted by a park ranger who manages the grounds. He began by walking us through a brief history of Angel Island State Park and how the land has been used over time. The island was once inhabited by local tribes, who appeared to conduct ceremonial burns of the region’s flora. This practice created a period of ecological stability, as periodic burns reduced wildfire risks and replenished the soil with organic material. However, this coexistence ended when Europeans arrived in the late 1700s. In the early 1800s, Mexico designated the island as private property, and it was used for cattle ranching and logging.

Despite its complicated history, the park today is a beautiful example of how restoration work can transform degraded landscapes into cherished natural spaces. After settlers arrived, the ecosystem suffered: deer were introduced and overgrazed the grasses, while blue-gum eucalyptus and conifers were planted to prevent erosion and beautify the island. The landscape was in poor condition. But San Francisco later recognized the island’s historical significance—especially after it was used as a detention center for Asian immigrants in the early 1900s. This led to its designation as a national park in the 1950s and the beginning of a slow restoration process.

Wait—non-native species helped?

As the ranger led us up the island’s hilly terrain, we saw how the landscape now more closely resembles its historical state. There are more shrubs than trees—plants native to the area. The deer population has also declined since coyotes arrived in 2017, allowing the vegetation to recover. The ranger looked up at the trees and sighed. He believed their removal was for the best. Yet, not everyone agrees. Some argue that the blue-gum eucalyptus trees should remain, claiming their removal could cause more harm than good.

When we reached the island’s other coast, the ranger discussed their conservation efforts. Many non-native plants have been removed through controlled burns, and others were destroyed in an unplanned wildfire that burned 40% of the island in 2008. The fire spread rapidly due to strong winds that made it impossible for fireboats to intervene. Still, only 40% of the island burned. The ranger then led us to buildings near the coast—remnants of the Immigration Station, where immigrants were held until granted entry. The walls still bear poems carved by those who endured hardship and uncertainty. These buildings, which hold the stories of thousands, were actually protected by the very eucalyptus trees the park is trying to eliminate. While eucalyptus often intensifies fires, in this case, their thick trunks and branches were more fire-resistant than the native flora, helping shield the buildings from destruction.

That’s not the only reason blue-gum is seen as a protector.

As we walked further inland, the eucalyptus trees grew denser. The air cooled, and a refreshing, invigorating scent filled the space. The ranger pointed upward. These were the blue-gum eucalyptus trees. They were never meant to be here and pose a fire risk due to their sap, which can fuel flames. Yet, the ranger explained why some groups still advocate for their preservation. These trees have become a favorite resting place for monarch butterflies, which visit the island and other parts of California to feed. As a result, the island has become a sanctuary for this endangered species. Butterfly conservationists often oppose the removal of these trees, fearing it would harm the monarchs. Still, the ranger stood by his position.

But they still need to go, right?

He believes the eucalyptus trees must be removed. Yes, they’re a fire hazard—but more importantly, they disrupt the ancestral environment. These trees and other invasive species have only been here for a few generations, while native species have evolved over thousands of years. We may not yet understand the full consequences of altering the island’s ecosystem. What about the insects, mammals, and microbes that depended on native plants for survival? Nature is incredibly complex. One human intervention can throw an entire ecosystem off balance. Native species have few places left to thrive, while eucalyptus trees flourish in their native Australia. Why prioritize a species that’s doing fine elsewhere over those that are struggling here?

No right answer.

In the end, the ranger brought us back to the port. Like many in his field, he knows that any conservation decision will have consequences. But doing nothing would be far worse. Had they allowed deer to overgraze unchecked, the island’s shrubbery would have vanished. Had they let the eucalyptus spread unchecked, the 2008 wildfire could have been catastrophic. Conservation solutions are rarely perfect. But for the sake of our ecosystems, we must move forward with the solutions that do more good than harm—before the consequences of inaction become irreversible.