Environment : Notes about your surroundings.

UNWANTED PLANTS: Upper Newport Bay, which so far has survived threats from development and siltation, is facing another threat: the destruction of native plant communities by invasion of weedy exotic plants that have escaped cultivation.

The intruders, chiefly pampas grass, castor bean and ice plant, are displacing native species along the shore of the bay as well as in the surrounding riparian and coastal sage scrub communities. That is bad news for wildlife, which depends on the native vegetation for food and shelter.

The Department of Fish and Game is recruiting teams of volunteers to remove the weeds and for mapping and photographic documentation of the work. Donations or loans of equipment are also being solicited. To volunteer, or for more information, write to Greg Gerstenberg, 615 S. Grand Ave., Orange, Calif. 92666.