The two groups plan to add native plants to the creek bank between Chaucer Street and Middlefield Road, even as they remove the mounds of non-native ivy.
At a meeting at Hopkins Park last week, Claire Elliott, Acterra senior ecologist, held up leaves she collected along the creek bank. Something from nearly every continent was represented there: Algerian ivy; French broom; and Tree of Heaven, a plant native to China.
It is far from heavenly, she said. A fast-growing tree and prolific seed bearer, the trees form dense thickets that prevent other plants from establishing nearby. And the extensive root systems can damage sewers and foundations.
"Why do we care about the ecosystem? Studies show that when we bring native plants back into an area, the biodiversity goes up," Elliott said.
Some imported species are good, she pointed out. Honeybees come from Italy and pollinate many food crops. But tiny native bees and wasps do an amazing job of pollinating crops, she said. Planting native manzanita bushes can attract the bees, which in turn can pollinate blueberry plants, which have the same flower structure as manzanitas, she said.
Elliott held up a few native plants. Some of the leaves were pocked with holes and crescents. The holes represent an important part of a healthy ecosystem. Insects feed on the leaves, and in turn provide needed protein for baby birds. But people like to cultivate non-native plants exactly because they are unpalatable to insects and animals.
"If we have a whole city of unmunchable plants, we won't have the baby birds that rely on the insects," she said.
Former Palo Alto Mayor Peter Drekmeier, a Crescent Park resident, has spearheaded the neighborhood group, which has cleared out mounds of ivy and planted native shrubs and trees, such as elderberry and coast live oak.
Dave Warner, whose home faces the creek, has avidly watered the saplings for more than a year, he said. Walking along winding Palo Alto Avenue last week, he spoke enthusiastically about his new, natural discoveries since a crew of 20 removed ivy along a roughly 50-foot stretch of bank. This spring, dozens of new plant species popped from the soil, he said.
The ivy clearing was aided by last year's Christmas Eve storm, which sent a torrent of water down the creek. When the water subsided, it deposited four inches of silt in the cleared area.
"There were all kinds of flowers — little tiny purple ones," he said.
Other neighbors have been more cautious about the creek restoration project.
"The preference of some people is for green rather than transitional brown," said Bonnie Luntz, whose home faces one of the restoration areas. She's asked the group to remove invasive plants in small patches and fill in with more native plants to maintain a continuity of greenery.
Junko Bryant, Acterra's watershed program coordinator, said the organization has already ordered 1,500 plants to restore bare areas. Native elderberry and California holly-leaved cherry could attract the little native gray fox where ivy once attracted Norway rats and vines strangled whole oak trees, she said. Acterra will supply a crew to water plants while they become established, she said.
This isn't the first time that environmentalists have sought to restore the creek banks. In the 1990s, Bay Area Action (now Acterra) filled 11 dump trucks with garbage taken from the creek, recalled Jerry Hearn. He was involved in a native-plant project near the pedestrian bridge at El Camino Park.
"Fifteen years ago, it was a moonscape. We redid the bank, and it's a beautiful park," he said.