Native Limestone Forest Restoration and Enhancement on Guam National Wildlife Refuge

The Guam National Wildlife Refuge (Refuge) is undertaking a major project to restore and enhance the native limestone forest on the Refuge with the goal of being able to bring back Guam’s forest birds. In coordination with species experts and other partners, this project will ensure there is enough native plants throughout the Refuge that meets the needs of all forest animals and that the forest is able to regrow with minimal human intervention.

The Refuge contains a couple hundred acres of limestone forest. The quality of the forest has been decreasing over time and was severely decreased as a result of Typhoon Mawar. Refuge Staff hope to restore and enhance the native limestone forest and create a strategy to maintain the newly restored forest. In 2009, the Refuge finalized its Comprehensive Conservation Plan¹, which specifies the management direction for the Refuge and identifies several goals, objectives, and strategies for the Refuge. This Project is being designed to meet Goal 1 in the Comprehensive Conservation Plan, which is the restoration of the native limestone forest. This project will implement several strategies and objectives described under Goal 1. The Refuge has partnered with USDA Wildlife Services to determine how best to control feral ungulates and to start the control effort. 

Project Need:

Several threats currently exist that impedes natural regrowth of a healthy mixture of native species, including non-native plant encroachment, feral ungulate tramping and grazing, and the loss of native pollinators and seed dispersers. Without active management, Refuge staff fear the forest will be overtaken by non-native species, which will negatively impact the forest species that currently use the Refuge and increase the difficulty in bringing back the forest birds.

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Goals and Objectives:

1. Document the current condition of the forest.
   1. Determine what species comprise different locations of the limestone forest and in what density.
   2. Conduct a rough forest inventory analysis at different locations.
2. Plan where forest enhancement and forest restoration need to take place.
   1. In conjunction with species experts, determine what species, in what quantity, and in what location each species needs to be outplanted throughout the Refuge. 
   2. Develop a Forest Restoration Plan (Plan) using advice from species experts and staff experience and expertise, determining what success looks like, and making sure the Plan includes protocols on how to monitor for success.
   3. Based on the Plan, determine what permits will be needed for implementation and apply for all permits.
   4. Determine how to minimize the impacts of feral ungulates on the east side of the Refuge outside of the multi-species barrier.
3. Prepare outplanting sites.
   1. Control invasive ungulates through trapping.
   2. Determine how hunting will impact the listed species that use the Refuge. If possible, control invasive ungulates through hunting.
   3. Control invasive plants through mechanical and chemical methods.
   4. Restore the multi-species barrier and implement feral ungulate exclusion techniques on the east side of the Refuge.
4. Implement a propagation program.
   1. Based on the Plan, collect seeds, cuttings, and other planting material from donor plants around the Refuge and propagate planting material in the nursery.
   2. Outplant species as described in the Plan.
   3. Implement the Plan’s monitoring protocols.

Project Benefits:

This project will provide Refuge staff a solid foundation for reintroducing forest birds back to the island of Guam. As the project nears completion, Refuge staff will work with experts, such as the USGS and other researchers, to start controlling the brown tree snake population within the multi-species barrier. Only after the habitat has been restored and the brown tree snake population has been controlled, can forest birds be reintroduced. 

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Project Updates:

Update for 8/25/2024

The Refuge is hosting three Kupu members, two of which will be focusing on invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species removal. The Refuge has partnered with USDA Wildlife Services to determine the best method for controlling feral ungulates based on the environmental conditions on the Refuge. Refuge staff have also been meeting with species experts and restoration experts to develop a plan on what successful restoration may look like for the Refuge and how to measure and maintain success.

References:

1. U.S. Fish and Wildlife Service. 2009. Guam National Wildlife Refuge Comprehensive Conservation Plan. 357 pages.