ANN ARBOR The city of Ann Arbors Natural Area Preservation is calling on local volunteers to help pull invasive spring plant species as part of a virtual event. Volunteers are encouraged to remove spring invasive species from their yards and gardens as well as city-owned nature areas. Each season, aggressive non-native plants spread and outcompete native species, reducing the diversity of native wildlife, including butterflies and small mammals. Residents are asked to pull plants on their own or with members from their household. After youve pulled the plants, report your efforts to the Stewardship Network Spring Invasive Species Challenge.