Experts Give Reseeding Program a Second Look : Ecology: Some specialists say seeding may interfere with regeneration of native plants and re-establishment of ecosystems as areas recover from wildfires.

To seed or not to seed. That was the question.

Ecologists, biologists and public policy-makers gathered Saturday for the Southern California Academy of Sciences annual meeting at UC Irvine to discuss October’s wildfires and whether vegetation should be replanted in burn areas to hold off mudslides.

While many of the researchers who discussed the fire’s impact on the local environment cautioned that their studies are still in progress, some said their findings show that reseeding may interfere with regeneration of native plants and re-establishment of ecosystems as an area recovers.

Jon E. Keeley, biology professor at Occidental College, said he has compared areas seeded with native grasses and unseeded areas burned in the Laguna Beach fire. Neither has bounced back strongly, he said.

“This year we didn’t see that seeding was particularly effective at all,” Keeley said.

“I’m not sure if it was because of the intensity (of the fire) or (lack of) rainfall.”

Keeley also compared the growth of plants in seeded and unseeded areas of the Santa Monica Mountains, which were burned in the Malibu wildfire. The density of regrowth differed little, he said.

“While reseeding may not have environmentally damaging effects, it may not be cost-effective,” Keeley said. “Should you spend half a million in reseeding?”

Todd Keeler-Wolf, vegetation ecologist with the state Department of Fish and Game, said introducing non-native plants to an area may make it possible that “in one generation you can completely swamp out native species.”

Keeler-Wolf said that grasses used in reseeding, which are chosen because they grow quickly and control erosion, might compete with native seedlings trying to grow back after fires.

But state Division of Forestry officials said they believe reseeding can work in areas of major damage. After future fires, “we’re going to have interdisciplinary teams look at each burn site and evaluate what it needs,” said Douglas Wickizer, staff chief for forest management with the forestry division. “And that may very easily include seeding.”

The two-day conference held Friday and Saturday attracted hundreds of people for sessions on topics ranging from earthquakes to local fish populations.

Many researchers called for further study of reseeding, but seven sixth-graders from Thurston Middle School in Laguna Beach have concluded that reseeding works if it’s properly done, but plants also grow back well by themselves.

“You can see when it’s sprayed too thick, the sun can’t get through it,” said Chelsea Weenig, 12, who displayed a picture of a large chunk of mulch and seeds that had been spread on a hill.

John Wilkerson, a Thurston science teacher and director of the school project, said his students are recognizing that many varieties of plants are growing back well in ash.

“They compare how plants are growing back without reseeding and you can see the money spent wouldn’t have been necessary,” he said.

One researcher who studied methods of stopping erosion said that hay bales blocking some Laguna Beach canyons may halt rocks and sand from reaching houses during small storms, but are “ticking time bombs” where accumulated debris can be unleashed in major rains.

The scientist, Tom Spittler, of the state Division of Mines and Geology, showed a slide of a massive boulder that had tumbled onto a La Canada-Flintridge road in 1934.

“I submit that a straw bale dam would have a hard time containing that,” he said.