How many species of plants, insects and animals live and grow in Pennsylvania's forests? The total figure is daunting.
But what residents and visitors may not realize is that some of those species actually don't belong here. Some of them are taking over landscapes and pushing out natives from their habitats. On occasion, these "invasives" destroy whatever native species are in their way.
You can help stop them.
A citizen scientist program is being developed to help state agencies such as the Department of Conservation and Natural Resources monitor where invasives have been found. Once they are pinpointed, biologists can develop strategies to try to eradicate them.
"Invasive species are having a major impact on the way we manage our state lands. Japanese knotweed grows along riparian corridors and makes boating and fishing access difficult," said Jessica Sparjcar, ecological program specialist with DCNR's Bureau of Forestry.
Common invasives include mile-a-minute weed, emerald ash borer and wooly adelgid, she said.
"Mile-a-minute vine grows over native vegetation, blocking sunlight so that the natives can't photosynthesize," Sparjcar said.
The borer and adelgid are killing off ash and hemlock trees, respectively, all across the state.
"Japanese barberry and other invasive shrubs impede forest regeneration. The list goes on and on," she said. "The cost to control these species, both in time and money, is enormous. And, the funds to do so are shrinking."
Visitors and tourists sometimes cause the spread of invasive species.
"The seeds of many of these plants, like Japanese stiltgrass and garlic mustard, can get stuck in the tread of hiking boots and bike tires, spreading from one place to another unless people clean off their gear before going to a new area," Sparjcar said.
The transport of firewood from one place to another is one of the reasons why the emerald ash borer made it to the state.
Sparjcar said that is another reason why the bug still is spreading eastward.
"People need to know that insects live inside firewood and will emerge sooner or later. They should always buy firewood where they are camping, not move it from county to county or state to state," she said.
Invasives also come from people's yards or flower beds, such as plants used in landscaping, which easily can be spread to the forested areas.
"Invasive plant seeds are spread by the wind, by water, on the fur of animals like deer. When birds eat the fruits of invasive plants and then fly to a new area, their droppings contain seeds that can sprout," Sparjcar said.
Invasives are dangerous because they can produce large amounts of fruit and seeds. This gives them a competitive advantage over the native plants here.
"Many can also spread through their roots and even tiny root fragments that break off can create a new plant. Invasive insects can also be prolific breeders," she said.
Because millions of people from other states and even countries visit Pennsylvania's parks and forests each year, it is important that they are aware invasives create problems.
"They may inadvertently bring in the next new invasive plant seed on the soles of their shoes," Sparjcar said. "We need for our visitors to be aware of what invasives are, why they can be destructive and how they can help prevent their spread."
The citizen science monitoring program will help get the public involved and make them aware.
"It's not just someone talking to them, trying to get a point across. The public will be actively engaged in learning what invasives look like, reporting their sightings to us and then hopefully getting involved in a control project where they can get their hands dirty removing these unwanted plants," Sparjcar said.
She hopes that they will follow up by taking their newfound knowledge back to their communities and start identifying invasive problems in their backyards, school yards and roadsides.