RENEE MONTAGNE, Host:
Sabri Ben-Achour has the story.
SABRI BEN: Bill McShea is a wildlife ecologist with the Smithsonian. And after passing through a rickety wire door...
(SOUNDBITE OF A METAL DOOR)
BEN: ...he is standing in that world.
BILL MCSHEA: So here we're inside this deer exclosure, right at the fence line here. And this fence has been up now for 21 years. So we're comparing inside the fence to outside the fence. And there's two things to notice. One is, it's green on both sides of the fence. But in here, it's a lot more diverse than out there.
BEN: That is an understatement. The deer side of the fence has a carpet of grass, a shrubby looking thing, and some large trees - things that are either too big for deer to eat, or are among the very few plants they don't like to eat. Inside it is practically a jungle. Dozens of different almost exotic looking plants are tumbling over one another. Many of them are young trees.
MCSHEA: In here, I can see white ash and hickory and red maples and service berry. We're looking at 20, 30 species. If you look out there, it's a much simpler world.
BEN: And that simpler world is an aging world. Really, it's a dying world, as far as forests go.
MCSHEA: The future is not good. There's no teenagers here. There's no young adults. Everybody is a mature individual. Whereas inside this fence, you have the complete profile of ages. You have youngsters. You have teenagers you have middle-aged adults. You have the old trees. And when the old trees go, there is something here to take its place. Out there, I don't see anything out there that's a small tree.
BEN: A hundred years ago deer were nearly extinct in Maryland and extremely rare in Virginia. Newly minted state game departments rushed to the rescue, banning or regulating hunting and setting up parks.
MCSHEA: They went and got deer from Arkansas and brought them here to repopulate that area. So growing the deer population was intentional. It's a conservation story and it went just like they planned. And now the flipside has happened.
BEN: Deer aren't evil, McShea is quick to emphasize, but they don't have any natural predators anymore and they need to be managed. States rely on hunters and even hired sharpshooters. But McShea says in order to protect the long-term health of forests, a wider, more aggressive approach is necessary.
MCSHEA: We have time in that we don't have to make a decision this year.
BEN: For NPR News, I'm Sabri Ben-Achour in Washington. Transcript provided by NPR, Copyright NPR.