Voice of San Diego
December 3, 2009
by Rob Davis
The barren, vegetation-free hillsides in Border Field State Park created by a new 3.5-mile section of the U.S.-Mexico border fence are neither barren nor vegetation-free, the federal government claims.
In a recent letter to U.S. Rep. Susan Davis, D-San Diego, the U.S. Customs and Border Protection's chief says the denuded hills near the Tijuana Estuary have plants growing on them.
You just can't see them, he wrote.
Because the plants being grown on the new hillsides are native species, wrote Jayson Ahern, the agency's acting chief, "the existing re-vegetated areas are currently dormant and brown ... and, thus, difficult to see from afar."
That does not accurately reflect what I've seen in the park. When I visited in mid-October, I saw a few plants growing on a single hill. Other new hills were barren, save for rows of straw bales.
It was easy to see from afar that no plants were growing. It was even easier to see up close. I stood on the hills. Plants were not growing. Federal contractors working for the U.S. Army Corps of Engineers had sprayed a wet, pulpy seed mix -- called "hydroseed" -- on the ground, but never irrigated.
I called Clay Phillips, superintendent of Border Field State Park, to check whether plants had suddenly grown in the last month.
"Nothing magical has happened," he said. "There is a native plant seed mix (on the ground), but we've never seen any growth there."
Ahern, the U.S. Customs and Border Protection official, wrote in his letter that "moderate revegetation has actually occurred and is progressing well." He said the federal government purposely didn't water the seeds it spread on the hills so it could mimic normal climatic conditions -- dry summers, wet winters.
I asked Bruce Hanson, a restoration ecologist for Edaw, a local consulting firm, whether that was a good idea. He said it is. Unless a full-fledged irrigation system was installed, Hanson said it's better to wait for natural rainfall, which helps seeds germinate better. The salt content is lower in rain than in water sprayed from trucks, which the government is now using.
But using seeds alone is "window-dressing," Hanson said. The best way to restore degraded habitat is to use a mix of seeds and transplant already-established plants and cactus, he said.
"A lot of species" -- such as the Baja birdbush, a plant whose northern range extends only to the border -- "never come up from seed," he said. Instead, generic shrubs grow, such as purple needlegrass, which is found throughout the state.
"You end up with a different plant community than what should be there," Hanson said. "Hydroseed is not going to be representative of what was out there."