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Simple plant at center of sand dunes battle

March 31, 2002|By LAURA MITCHELL

Staff Writer

The source of much of the battle at the Imperial Sand Dunes is a purple-flowered plant on the threatened species list.

The Center for Biological Diversity, the Sierra Club and Public Employees for Environmental Responsibility sued the U.S. Bureau of Land Management in November 2000 to force the protection of the threatened Peirson's milkvetch.

The suit resulted in the BLM closing over 49,000 acres of the dunes from off-road vehicles.

The American Sand Association is taking steps to have Peirson's milk vetch taken off the threatened species list. Last week the group


filed a 60-day notice to sue with the U.S. Fish and Wildlife Service.

Peirson's milk vetch, astragalus magdalenae var. peirsonii, is a legume with purple flowers and pods carrying kidney-shaped seeds found only in the Imperial Sand Dunes and dunes in Mexico.

"Their petition simply shouldn't go anywhere," Center for Biological Diversity attorney Brendan Cummings said. "Everyone who's studied these

dunes and this plant considers them endangered."

Although he hasn't studied the Peirson's milk vetch specifically, Martin F.

Wojciechowski, an assistant professor of plant biology at Arizona State University, has studied and published studies on milk vetches.

Many species are characterized by being localized, Wojciechowski said. From year to year there can be tremendous variation in the numbers of a species.

Last year was a wet year in the desert and anyone counting plants would have found large numbers, he said. This year is a dry year. Someone counting plants probably won't find many.

But the big concern is how healthy the population is genetically, Wojciechowski said. If plants are the same genetically, they are all susceptible to the same genetic shocks.

Wojciechowski said large populations will have a healthy genetic variety and will be able to survive disease. A population of milk vetch with thousands of individuals is a reasonably healthy population, he said.

>> How many Peirson's milk vetches are there?

The ASA hired Thomas Olsen Associates of Hemet last spring to count several plants in the Imperial Sand Dunes, including Peirson's milk vetch.

Olsen's team, lead by botanist, Arthur M. Phillips, III, counted more 71,000 Peirson's milkvetch. A report on Phillips' study is available on the

ASA Web site.

Environmentalists say the report is flawed and Phillips is just a "scientist for hire."

The ASA paid for a study to show what they wanted to show, Center for Biological Diversity Desert Ecologist Daniel Patterson said.

"We've been challenging the ASA to put this study out for peer review and they've refused," Patterson said.

Phillips said the ASA paid him but he does not have any stake in the study. He has worked on similar studies for endangered species for the Fish and Wildlife Service since the 1980s.

"I'm usually on the other side of the fence," he said.

Phillips said he has been responsible for putting a lot of plants on the endangered species list in Arizona.

The Olsen group had to start from scratch because previous monitoring by the U.S. Bureau of Land Management counted the plants only at fixed

locations, called transects, within the dunes.

Phillips said using transects to count the Peirson's milkvetch is not the best way to get accurate numbers because the plants are clustered in basins.

The Peirson's milkvetch was by far the most abundant plant in the dunes at the time the Olsen team was counting, he said.

About an inch of rain fell on the dunes in October 2000 and started the population explosion, Phillips said. He said it looked like all the plants germinated at that time.

But the ASA would have been in trouble if the count was done the year before, he said.

"Of the over 71,000 Peirson's milk vetch we counted, only five were older than October 2000," Phillips said.

>>How did five plants turn into 71,000?

The seeds were there all the time, waiting for the right conditions, Phillips said. Individual plants do not survive dry spells. They are adapted to survive through their seeds.

This year Phillips is working on a seed bank study for the ASA, which should be ready at the end of April.

He said he's seen hundreds of Peirson's milk vetch plants at sites this year where he counted thousands last year. About 20 percent of the plants from last

year survived, he said.

But of those plants, the seed production is much higher. He counted up to 400 seed pods on second-year plants. Seed production should be five times

what it was last year, he said.

Phillips said he's done a lot of work on endangered species for the Fish and Wildlife Service. All that experience gives him a "gut feeling" that the Peirson's milkvetch should not be listed.

He added the Olsen study will be peer reviewed when the Fish and Wildlife Service studies it.

"I don't believe there was enough information available when it was originally listed," he said.

The plant's listing on the threatened species list is not based on any particular study, Phillips said.

Patterson said the listing was based on the fact that the Peirson's milk vetch only occurs in the Imperial Sand Dunes and is faced with impact from off-road vehicles. The plant needs protection from that impact and

before the listing, there was no protection, he said.

>> Staff Writer Laura Mitchell can be reached at 337-3452 or

>> On the Web:

American Sand Association:, soon to be

Center for Biological Diversity:

Imperial Valley Press Online Articles