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Forest management, species preservation at center of holistic approach to ecosystem management at Fort Knox

By Thomas Milligan (USAEC)May 30, 2023

Indiana bat monitoring efforts occur annually at Fort Knox to better understand how Indiana bats use the landscape and interact with the ongoing mission. Fort Knox has two of the largest known Indiana bat maternity colonies. As many as 595 bats have been documented emerging from an artificial roost structure like the one pictured center of the background above.
1 / 6 Show Caption + Hide Caption – Indiana bat monitoring efforts occur annually at Fort Knox to better understand how Indiana bats use the landscape and interact with the ongoing mission. Fort Knox has two of the largest known Indiana bat maternity colonies. As many as 595 bats have been documented emerging from an artificial roost structure like the one pictured center of the background above. (Photo Credit: US Army) VIEW ORIGINAL
This is an example of forb response after cedar harvest followed by prescribed fire within a hardwood stand. This herbaceous component increases invertebrate abundance which is the forage base for forest dwelling bats as well as many neotropical migratory birds. The removal of the cedar “clutter” also enhances foraging by bats below the forest canopy
2 / 6 Show Caption + Hide Caption – This is an example of forb response after cedar harvest followed by prescribed fire within a hardwood stand. This herbaceous component increases invertebrate abundance which is the forage base for forest dwelling bats as well as many neotropical migratory birds. The removal of the cedar “clutter” also enhances foraging by bats below the forest canopy (Photo Credit: US Army) VIEW ORIGINAL
Injection of exotic and undesirable woody species is a primary focus of Fort Knox’s forest management. Kevin Bunkowske uses an injection technique “hack and squirt” which is a 20% solution of 53.1% imazapyr and water, applied when sap flow is not a concern. A 50% solution of clopyralid and water is used for species such as redbud, kudzu and black locust.
3 / 6 Show Caption + Hide Caption – Injection of exotic and undesirable woody species is a primary focus of Fort Knox’s forest management. Kevin Bunkowske uses an injection technique “hack and squirt” which is a 20% solution of 53.1% imazapyr and water, applied when sap flow is not a concern. A 50% solution of clopyralid and water is used for species such as redbud, kudzu and black locust. (Photo Credit: US Army) VIEW ORIGINAL
Fort Knox Natural Resources staff installed an artificial bat roost structure in October 2021. The structures use repurposed utility poles sourced at no cost from the local Rural Electric Cooperative Corporation. These structures are often used the first maternity season after placement and to date, five species of bats have been documented to use them throughout the areas it has been deployed, primarily housing Indiana bats but also used by northern long-eared bats, little brown bats, big brown bats, and evening bats.
4 / 6 Show Caption + Hide Caption – Fort Knox Natural Resources staff installed an artificial bat roost structure in October 2021. The structures use repurposed utility poles sourced at no cost from the local Rural Electric Cooperative Corporation. These structures are often used the first maternity season after placement and to date, five species of bats have been documented to use them throughout the areas it has been deployed, primarily housing Indiana bats but also used by northern long-eared bats, little brown bats, big brown bats, and evening bats.

(Photo Credit: US Army) VIEW ORIGINAL
Barrens, grasslands and glades are managed at Fort Knox to enhance biodiversity and are important habitats to many species. Mowing, disking, prescribed fire, and herbicide treatment are used to maintain native plant communities. This area is one parcel of approximately 200 total acres that is no longer in the mowing contract saving base maintenance costs and providing excellent pollinator habitat.
5 / 6 Show Caption + Hide Caption – Barrens, grasslands and glades are managed at Fort Knox to enhance biodiversity and are important habitats to many species. Mowing, disking, prescribed fire, and herbicide treatment are used to maintain native plant communities. This area is one parcel of approximately 200 total acres that is no longer in the mowing contract saving base maintenance costs and providing excellent pollinator habitat. (Photo Credit: U.S. Army) VIEW ORIGINAL
Fort Knox has two of the largest known Indiana bat maternity colonies. Monitoring efforts on these colonies have occurred to determine roost use, foraging habitat, dietary analysis, and response to mechanical disturbance. All bats captured are fitted with a wing band.
6 / 6 Show Caption + Hide Caption – Fort Knox has two of the largest known Indiana bat maternity colonies. Monitoring efforts on these colonies have occurred to determine roost use, foraging habitat, dietary analysis, and response to mechanical disturbance. All bats captured are fitted with a wing band. (Photo Credit: U.S. Army) VIEW ORIGINAL

Approximately 80% of Fort Knox is covered in forests – which not only helps create an ideal training ground, but also is critical habitat for numerous plant and animal species, including some that are endangered.

As part of its holistic approach to ecosystem management, the natural resources team at Fort Knox has undertaken efforts aimed directly at protecting and preserving forest health, which in turn has created a broader impact and improved habitats.

“Our team has worked incredibly hard to implement plans and projects to produce results,” said Michael Brandenburg, Fort Knox Natural Resources Branch chief. “This work has resulted in improved wildlife habitat, better summer habitat for endangered bats, improved water quality, and enhanced military training opportunities.”

In the last two years, Fort Knox crews completed 1,060 acres of forest stand improvement and 1,166 acres of forest invasive species control, providing improved habitat for the species that live in the area.

The team also managed invasive species on 356 acres and improved the land to promote both pollinator and quail species success. The team also managed 100 acres of cool season and 26 acres of warm season wildlife plots, providing more year-round habitat.

Much of this work centers on promoting the Oak-Hickory forest type that is naturally occurring in the area and removing and impeding the expansion of invasive tree and plant species, including tree of heaven, Princess tree, Callery Pear, bush honeysuckle, autumn olive, multiflora rose and Japanese stilt grass.

One of the more innovative additions to the post were the installation of 12 bat roost structures that blend into the natural environment but provide longer lasting habitat for bats. Compared to natural roosts which exhibit suitable roosting habitat for approximately one to five years, the artificial roost structures useful lifespan is much longer.

Recently, population studies of Indiana bats have been conducted by banding hundreds of individuals each year resulting in approximately 3,000 bats in each of two Indiana bat colonies on base. Additionally, 595 bats have been documented emerging from a single BrandenBark® roost structure housing Indiana bats at Fort Knox. These are by far the largest Indiana bat colonies in the range of the species.

Fort Knox is part of a larger and ongoing effort to protect bats. Since 2005, the Fort Knox NR Program, in cooperation with U.S. Fish and Wildlife Service, Kentucky Ecological Field Office and consulting firm partners, has conducted survey and monitoring efforts for bats on the installation.

Brandenburg said there have been 3,545 captures of 10 species of bats at Fort Knox over 15 years. During several years, northern long-eared bats were targeted for study and one year, tricolored bats were radio-tracked. Most of the focus has been on the Indiana bat, including capture on the landscape; capture at roosts; and documenting land use using telemetry and acoustic technology.

The team has also supported creation and preservation of recreational opportunities for the Fort Knox community. Some of the more notable efforts have included improvements to fishing habitat by installing more than 75 fish habitat structures, often converting waste materials, and constructing habitat appropriate structures for fish. The team also stocked Otter Creek on Fort Knox with 3,000 pounds of rainbow trout and managed other lakes with 10,000 pounds of catfish.

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