Looking into a dense forest and assuming it's healthy is called the "green lie," but under the lens of an environmentalist like Carl Martin, you realize something is very wrong.

"This is everywhere. It's called Japanese stilt grass," Martin explained while at the Wildlands Conservancy Pool Sanctuary in Emmaus, Lehigh County.

Martin said this is just one example of invasive species that are killing urban forests throughout the Lehigh Valley and southeastern Pennsylvania.

"Nothing eats it. This occupies growing space, meaning it will take sun away from plants, nutrients out of the soil." Martin explained.

That leaves virtually no room for native plants and trees to grow, and despite the sea of green, little food for animals to eat.

"This is happening at a rapid rate. We are losing a lot forage for native animals, birds insects and so forth," Martin added.

At Wildlands South Mountain Preserve, a clear patch of blue sky could be seen, however, a green canopy should be covering the space.

Martin said the future of area forests could be no trees, vines and plenty of invasive species.   

The Emmaus-based Wildlands Conservancy is working to combat the problem throughout its nine preserves. Crews are clearing out invasive species, making room for native, viable vegetation.

Martin is hoping deer enclosures, which are large, fenced-off areas where natural fauna flourish, can be a teaching tool for the public.

"People will walk by our nature center. They'll look into this, and if looking for it, ask a question why is this different than out there," he said.

Think of the enclosures as fully stocked supermarkets for animals, outside the enclosure being nothing but empty shelves.

"This is the type of regeneration you'd expect if you take the deer out of the equation," Martin explained while inside one for the enclosures.

Proving Wildlands is laying the groundwork for a future where people can see the forests with the trees.