COUNTY

Jennings Environmental Education Center, Route 528, Brady Township, hosts Take Back the Woods: Battling Invasive Species from 9 a.m. to 1 p.m. April 18. Registration is required by Friday. Call 724-794-6011.

REGION

McConnells Mill State Park in Slippery Rock Township, Lawrence County off Route 422, will host “Hemlocks of Hell’s Hollow” from 10 a.m. to noon Saturday. The hike is easy to moderate. Meet at the Hell’s Hollow Trail parking lot. Call 724-368-8811.