The New York Times has published an excellent story about the importance of the 30 million Department of Defense-owned acres in the U.S. for wildlife. It's worth your time to give it a read.
It is amazing that, not even a decade ago, the Pentagon was seeking exemptions from the reach of the Endangered Species Act. Now, the military is "gung ho" about this aspect of their mission to the tune of spending about $300 million per year on it.
And the armed forces' commitment, while not without controversy or challenges to its primary mission of national security, has also benefited, in many cases, entire ecosystems.
It will be quite interesting to see how the importance of federal military installations for wildlife is continues to be reflected in DoD efforts as more and more of the nation's wildlife becomes stressed due to human economic activities and climate change.