Native plant restoration not enough to maintain tropical dry forests in Hawaii

July 2, 2012, USDA Forest Service

Protecting Hawaiian dry forests from invasive species and the risk of wildfire is an on-going challenge for land managers and scientists conducting research on the Island of Hawaii. It is commonly thought that removing the invasive species and planting native species will restore the land to its original state. However, in a recent paper published in Biological Invasions, Dr. Susan Cordell, USDA Forest Service Pacific Southwest Research Station, Institute of Pacific Islands Forestry; Dr. Erin Questad, Cal-Poly Pomona; and Dr. Jarrod Thaxton, University of Puerto Rico found that it is not quite that simple.

The research team has been working at the Kaupulehu dry on the Island of Hawaii for the past decade. The largest current threat to this highly unique and endangered ecosystem is the spread of non-native fire-promoting grasses, in particular, fountain grass or Pennisetum setaceum.

To test characteristics of ecosystem resilience in this dry tropical forest, the researchers allowed natural rates of re-invasion of non-native species into an existing restoration project and looked at how effective restoration projects were at enhancing invasion resistance. They paid particular attention to the relationship between invasibility and native .

Key findings from the research include:

  • Higher invasion rates occurred in plots that supported the most native species, suggesting that similar mechanisms may regulate the distribution of both native and invasive species.
  • Fountain grass was associated with native plant mortality and declines in native diversity, particularly in areas with harsh environmental conditions (i.e. steep slopes, little soil, exposed terrain).
  • Native restoration alone was not an effective tool for weed control in this community, and continuing invasion may result in declines in native diversity in the long term.

"We have spent a considerable amount of time understanding the role of restoration on non-native plant invasion," says Dr. Cordell. "In the short term, restoration of native species serves to improve invasion resistance —but results from this study also indicate that long-term sustainability of restoration projects will require continued non-native species management."

These findings suggest the need for consideration of long-term sustainability measures in plans for tropical dry forest ecosystems in Hawaii.

Explore further: Reforestation efforts reshape Hawaii's soil hydrology

More information: To read the full report, "Patterns and Consequences of Re-invasion into a Hawaiian Dry Forest Restoration," go to: treesearch.fs.fed.us/pubs/40891

Related Stories

Reforestation efforts reshape Hawaii's soil hydrology

March 31, 2012

Starting with the arrival of Polynesian settlers in the fourth century, and peaking in the mid-1800s, the destructive forces of wildfires and pests and the grazing of feral pigs, goats, and cattle reduced the native forests ...

Insect release proposed to control exotic strawberry guava

May 22, 2008

U.S. Forest Service scientists with the Institute of Pacific Islands Forestry have submitted a proposal to release a Brazilian insect to control the spread of strawberry guava, a South American tree that has invaded and degraded ...

Recommended for you

Common weed killer linked to bee deaths

September 24, 2018

The world's most widely used weed killer may also be indirectly killing bees. New research from The University of Texas at Austin shows that honey bees exposed to glyphosate, the active ingredient in Roundup, lose some of ...

Birds' voiceboxes are odd ducks

September 24, 2018

Birds sing from the heart. While other four-limbed animals like mammals and reptiles make sounds with voiceboxes in their throats, birds' chirps originate in a unique vocal organ called the syrinx, located in their chests. ...

Desert ants have an amazing odor memory

September 24, 2018

Scientists at the Max Planck Institute for Chemical Ecology used behavioral experiments to show that desert ants quickly learn many food odors and remember them for the rest of their lives. However, their memory for nest ...

Custom circuits for living cells

September 24, 2018

A team of Caltech researchers has developed a biological toolkit of proteins that can be assembled together in different ways, like Legos, to program new behaviors in cells. As a proof-of-concept, they designed and constructed ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.