Guam National Wildlife Refuge Comprehensive Conservation Plan

Guam National Wildlife Refuge Comprehensive Conservation Plan
Environmental harm may also include detrimental changes in ecological processes. For example,
cheatgrass infestations in shrub steppe habitat can alter fire return intervals, displacing native
species and communities of bunch grasses, forbs, and shrubs. Environmental harm may also
cause or be associated with economic losses and damage to human, plant, and animal health. For
example, invasions by fire-promoting grasses that alter entire plant and animal communities,
eliminating or sharply reducing populations of many native plant and animal species, can also
greatly increase fire-fighting costs.
See Appendix J for the Refuge’s IPM program documentation for managing pests for this CCP.
Along with a more detailed discussion of IPM techniques, this documentation describes the
selective use of pesticides for pest management on the Refuge, where necessary. Throughout the
life of the CCP or HMP, most proposed pesticide uses on the Refuge would be evaluated for
potential effects to the Refuge’s biological resources and environmental quality. These potential
effects would be documented in “Chemical Profiles” (see example in Appendix J). Pesticide uses
with appropriate and practical best management practices (BMPs) for habitat management as
well as cropland/facilities maintenance would be approved for use on the Refuge where there
likely would be only minor, temporary, and localized effects to species and environmental quality
based upon non-exceedance of threshold values in Chemical Profiles. However, pesticides may be
used on a refuge where substantial effects to species and the environment are possible (exceed
threshold values) in order to protect human health and safety (e.g., mosquito-borne disease).
3.2 Description of Management Direction
We intend to install a multi-species barrier “wall” along the Ritidian Unit boundary on the east
end to the cliff, and on the west end to tie into the Air Force’s ungulate fence proposed for the Air
Force Overlay Unit. A concrete barrier is necessary to withstand a typhoon. The barrier would be
ungulate, rodent, and snake proof, and if implemented, could result in a nearly pest-free Refuge.
Management efforts would involve an initial investment in the cost and effort of constructing a
physical barricade. Once completed, pest species from within the confines of the pest barricade
would be removed. The USGS has developed this type of snake and rodent barrier.
The efforts necessary to keep pest species from repopulating the area are hoped to be a minimal
maintenance level. The barrier itself needs to be coordinated between Andersen AFB and the
Service. The combination of Service and AFB fencing would serve to encompass landholdings
from both agencies. The current proposed AFB fencing project includes three separate fenced
units and is proposed as an ungulate-excluding fence only. Refuge staff will coordinate with AFB
and Service Ecological Services staff to determine whether or not there are opportunities to
partner in a way that would be most advantageous to Guam’s native wildlife. Initial discussions
between some of the parties regarding type of fence and final locations have taken place. It is
possible that the Refuge staff would change the material that is used for the fencing project or the
specific location. Either of these changes would not change the nature or scale of the impacts that
are described in the Guam Refuge CCP/EA. The enclosed area will be large enough to
accommodate the spatial needs of native crabs and lizards.
Ungulate control will increase with the use of snares, and will be more effective with a wall in
place (eliminating ingress). Pest plants will be controlled with the use of pesticides and manual
removal. Native plant propagation and out-planting will be conducted following the removal of
ungulates. Survival of young plants will increase dramatically without ungulates eating and
Chapter 3. Management Direction 3-3