USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
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Research Topics: Biological Control

About this Research:
Biological Control of Strawberry Guava in Hawaii

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Participating Programs:
Native Hawaiian Forest, photo by Jack Jeffrey, US Fish and Wildlife Service
Photo by Jack Jeffrey, US Fish and Wildlife Service

Native Forests: A Resource at Risk

Native forests and the many products and services they provide are seriously threatened by invasive species.

Benefits of Native Forests

Hawaii's native forests and their inhabitants evolved in relative isolation over millions of years. As a result, many of the islands' plant and wildlife species are found nowhere else on Earth.

Healthy native forests provide society with numerous invaluable products and services, including:

  • Clean water and air
  • Carbon sequestration
  • Food and habitat for native birds and insects
  • Biodiversity
  • Harvestable products
  • Cultural and recreational opportunities
What Is an Invasive Species?

"Invasive species" is a term used by scientists and land managers around the world to describe plants, animals, and other organisms that are both nonnative to an ecosystem and that cause--or are capable of causing--environmental, economic, or human harm. Invasive species often compete so successfully in new ecosystems that they displace native species and disrupt important ecosystem processes. Plants, mammals, birds, fish, insects, and diseases all can be invasive, though not all introduced species act invasively. Often, species become invasive when they compete aggressively for resources and when they lack natural enemies in the new ecosystem.

What Effect Can Invasives Have?

People depend on healthy functioning ecosystems for many of our basic survival needs -- like fresh air; clean water; and harvestable resources, like wood. When invasives become established in a landscape, they can strongly affect how ecosystems function and can negatively impact ecosystems in a variety of ways. Left unchecked, many invasive species will outcompete native species, eventually replacing them entirely.

The Threat of Invasive Species

The same geographic isolation that influenced the unique evolution of Hawaii's forests also makes them especially sensitive to nonnative invasive species and other disturbances today.

In Hawaii, invasive species are transforming native landscapes and erasing millions of years of natural history. To date, invasives have taken over more than half of Hawaii, affecting hundreds of animal and plant species. Already, Hawaii has lost more than half of its native birds; of those that remain, another half are endangered, meaning they are seriously at risk of being lost forever. Strawberry guava, an invasive tree, directly threatens about a quarter of the state's endangered plants and has the potential to overrun and degrade hundreds of thousands of acres of remaining native forests.

Future embedded video placeholder: Invasive species characteristics and effects
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