Presented by Lena Schnell (CEMML) at the National Military Fish and Wildlife Association’s 2019 annual meeting and training workshop. Hawaiian dryland ecosystems evolved in the absence of grazing mammals. Non-native ungulates negatively impact these ecosystems by altering ecological processes and consuming rare native plants. At Pohakuloa Training Area (PTA) on Hawaii Island, dryland habitats support 26 threatened and endangered species, some exceedingly rare and most of which are negatively affected by non-native ungulates. To offset training-related impacts at PTA by protecting these species and their habitats, the US Army Garrison – Pohakuloa (USAG-P) constructed fourteen ungulate-proof fence units totaling 140 km of liner fence and encompassing about 15,100 ha of dryland habitat. Construction began in 2007 and was completed in 2017 at a cost of $10M. During pre-construction, we developed GIS methods to demarcate the installation boundary in remote areas that lacked survey boundary markers. During construction, we developed technical construction methods for lava-rock surfaces and improved logistics for work in remote areas with no road access including helicopter-assisted construction. The fence units were declared ungulate free in 2017. Post-construction challenges continue with developing reliable techniques to detect ingress, fence inspection and maintenance, and removal of trespass animals, as needed. Operational challenges include communication with the military about training opportunities/restrictions within the fences and compliance with gate discipline. We are partnering with the USAG-P Department of Public Works to design and install wildlife crossing guards to reduce potential ingress due to open gates and to facilitate traffic flow to key military ranges and assets within the fences. To quantify the impacts of feral ungulate removal on the biodiversity, structure, and function on dryland ecosystems and to test methods for promoting native plant recovery, we are partnering with researchers under a Strategic Environmental Research and Development Program (SERDP) grant. Preliminary findings indicated that system recovery depends on ecological condition at time of ungulate removal and time since removal.