Guardians of the Hawaiian Forest:
A Call for Conservation
This series highlights the invasive threat of strawberry guava to Hawaiʻi’s native forests, with a focus on its impact on two keystone species: ʻōhiʻa lehua and koa. This serves as a call to action for conservation and the protection of Hawaiʻi’s fragile ecosystem.
ʻŌhiʻa Lehua and Koa’s Most Important Role
Water is the lifeblood of any ecosystem, and the ʻŌhiʻa Lehua and Koa trees are essential to Hawaiʻi’s water cycle. Their extensive root systems help stabilize soil, reducing runoff and erosion, which ensures that rainfall and mist are effectively absorbed into the ground. This replenishes aquifers, Hawaiʻi’s primary source of fresh water. Both trees also slow water flow across the forest floor, allowing more time for it to seep into the soil, preventing it from being lost to the ocean.
ʻŌhiʻa Lehua's Role in the Ecosystem
The ʻŌhiʻa Lehua tree is a pioneer species, able to grow in barren volcanic landscapes and pave the way for other plants to thrive. Its vibrant flowers provide nectar for native birds as well as insects like native bees. The tree also captures and channels rainwater, mist, and dew efficiently through its canopy and leaf structure. Its ability to absorb moisture from multiple sources and pass it to the forest floor makes it more efficient at gathering water than many other trees, especially in Hawaiʻi’s often dry or mist-heavy climates.
Koa's Role in the Ecosystem
Koa trees provide stability to steep slopes, preventing landslides and protecting watersheds from sediment buildup. Their nitrogen-fixing roots enrich the forest soil, creating a nutrient-rich environment that supports the growth of other native plants. Koa also provides essential habitat for many native bird species, which depend on its canopy and wood for shelter and food. By stabilizing the soil and enriching the ecosystem, koa trees enhance the overall resilience of the forest.
Strawberry Guava and Why It’s So Invasive
Strawberry guava is one of the most aggressive invasive species in Hawaiʻi. Its density is its greatest threat—strawberry guava forms thick, impenetrable thickets that crowd out native trees like ʻŌhiʻa Lehua and Koa by blocking sunlight and monopolizing water and nutrients.
The tree produces an abundance of seeds, which cover the forest floor and prevent native species from regenerating. Its seeds are spread widely by animals like birds and feral pigs, creating rapid and widespread colonization.
Its roots are shallow but aggressive, extracting water and nutrients at the expense of native plants. Instead of aiding watersheds, strawberry guava disrupts water cycles by consuming large amounts of water and limiting groundwater recharge. This dense growth also reduces biodiversity by creating monocultures where only invasive species thrive.
Human Intervention is Essential
Without human intervention, invasive species like the strawberry guava will continue to outcompete native flora and fauna, destabilizing Hawaiʻi’s delicate ecosystems and depleting its water supply. To restore balance, active measures such as removing invasive trees, planting native species, and employing biocontrol agents are critical.
A striking example of human intervention can be seen in a forest divided by a path of chopped-down strawberry guava trees. On one side, dense thickets of strawberry guava dominate the landscape. On the other, young koa trees are taking root, symbolizing hope and renewal. This contrast illustrates the profound impact of conservation efforts and the importance of taking action to protect Hawaiʻi’s forests.
Fragile Balance: Loss Below, Life Above
The first captures the stark reality of invasive strawberry guava climbing steadily toward the summit, its grey canopy a harbinger of loss, choking out native life and signaling the fragility of Hawaiʻi’s ecosystems.
The second image, taken nearer the summit, offers a glimmer of hope—a vibrant native Hawaiian forest, still thriving with ʻŌhiʻa Lehua and Koa trees standing tall and resilient. These two scenes tell a story of urgency and possibility, reminding us of what’s at stake and inspiring action to protect the forests that sustain us all. The choice to act is ours, and the time is now.
The Impact of Volunteers and Supporters on Conservation
Volunteers are the heart of conservation efforts in Hawaiʻi. By engaging in projects such as removing invasive species, planting native trees, and restoring habitats, they play a critical role in safeguarding Hawaiʻi’s forests. Their hands-on contributions help ensure that native species like the ʻōhiʻa lehua and koa thrive, preserving biodiversity and protecting the watersheds vital to sustaining life on the islands.
Whether you’re in Hawaiʻi or elsewhere, you can make a meaningful impact on the environment. Locally, get involved through platforms like Conservation Connections, which links volunteers to restoration projects and educational opportunities. For those outside Hawaiʻi, consider donating to the many conservation organizations listed on the site, supporting efforts to preserve native forests, protect endangered species, and restore fragile ecosystems.
Every effort—whether volunteering, donating, or raising awareness—makes a difference. Together, we can protect Hawaiʻi’s forests and ensure their survival for future generations.