An environmental group on Wednesday accused the U.S. Bureau of Land Management of neglecting science in favor of politics while the agency conducts six ecological studies covering millions of acres and a variety of landscapes across the West.

The BLM ignored concerns raised by scientists by not evaluating livestock grazing as one of the most significant causes of environmental change on Western public lands, the group Public Employees for Environmental Responsibility wrote in a complaint filed with the BLM.

The group says the BLM did so out of fear of backlash, including the threat of litigation, from the livestock industry. The complaint quoted as evidence the minutes of a workshop the BLM held in Colorado last year to plan one of the regional studies.

"The idea that you could do an ecological map of the West and ignore grazing is preposterous," PEER executive director Jeff Ruch said.

Interior Department spokesman Adam Fetcher said the department would review the complaint under its scientific integrity policy.

The complaint centers on six "rapid ecoregional assessments" covering 12 states. Since last year the BLM has been working on seven assessments, including one in Alaska not included in the complaint, with help from federal economic stimulus funding.

The BLM plans to use the assessments to guide public land management after they're completed next year. They draw from existing data to evaluate how four "change agents" _ climate change, wildfires, invasive species and human development _ are affecting ecosystems.

Livestock grazing wasn't included as a change agent despite the fact that it is allowed on two-thirds of all BLM lands, or a total of 157 million acres, according to PEER.

"This is, from what we can tell, the biggest scientific effort ever undertaken by the BLM. And they've got it all wrong," Ruch said.

The BLM held a workshop in Lakewood, Colo., last year to discuss plans for an assessment covering the Colorado Plateau in Colorado, Utah, Arizona and New Mexico. The manager of the rapid ecoregional assessment program, Karl Ford, said at the meeting that livestock grazing was contentious, BLM officials were concerned about litigation, and that including grazing could put a stop to future regional assessments, according to the PEER complaint.

Workshop participants then discussed how much emphasis would be put on grazing. One participant said the BLM would be "laughed out of the room" if it didn't include grazing.

"If you have the other range of disturbances, you have to include grazing," Tom Edwards, a U.S. Geological Survey ecologist and peer reviewer for the assessment, was quoted as saying in the meeting minutes obtained by PEER.

Later, the BLM decided that any analysis of data on livestock grazing would be incorporated into data on grazing by other animals, such as antelope and wild horses.

"BLM not only decided they weren't going to look at grazing as a change agent even though there's a massive amount of grazing going on those public lands, but even went further and said grazing information could only be reported in an undistinguished lump where you had to put all ungulates together," Ruch said.

The BLM ultimately has given relatively low-impact activities, such as rock hounding, more weight in its assessments than grazing, he said.

The six assessments cover portions of a dozen states: Montana, the Dakotas, Nebraska, Wyoming, Idaho, Nevada, Utah, Colorado, California, Arizona and New Mexico.

This is the second complaint PEER has filed this year under the Interior Department's new scientific integrity rules. A previous complaint focused on the suspension of a wildlife biologist who studies polar bears.