Small trees that are spreading in the state are starting to cause big problems for the native ecosystem and ultimately creating human health concerns.

"You'll see these trees that are starting to pop up and that's the Amur corktree," says Christian Allyn with Invasive Plant Solutions in North Canaan.

The aggressive spreading Amur corktree is starting to cover parts of Litchfield County, including in Sharon and Warren. It's even been seen in Greenwich.

"The Amur corktree originates from the Amur region of China, which is roughly the northwest region," says Allyn.

Allyn says the tree is spreading quickly from New York and crowding out native ash trees that have been dying off. He says the bright yellow inner bark of the Amur corktree is soft and weak-wooded. Allyn says the tree is also allowing other invasives such as Japanese barberry and bittersweet to create serious health concerns.

"The barberry is covered with thorns, and underneath the barberry, which can grow up to 6 feet high, creates somewhat of a dome where mice can hide under that area and reproduce more, leading to more ticks," says Allyn.

Allyn says the barberry can create 120 ticks per acre. Without the barberry, there may be only 10 ticks per acre.

Allyn says the best way to kill the Amur corktree is with an herbicide treatment.

He says Connecticut has already lost about 10% of its forests.

Experts say anyone who sees invasive plants like the Corktree should report it to the Connecticut Invasive Plant Working Group