Environmental and conservation groups, which have fought to preserve the 19-million-acre refuge for decades, say that seismic testing, not to mention eventual drilling and production of oil and gas, could irreversibly alter the 1002 Area and potentially affect the habitat and behavior of caribou, polar bears and other animals there.

“There’s not a lot in here that you can look at and feel good about,” said Kristen Miller, conservation director of the Alaska Wilderness League, referring to a plan for testing in the 1002 Area put forth this year by a s eismic services company, SAExploration, and two Alaska native corporations.

That plan proposes that testing begin this winter, when ice and snow provide some protection to the tundra, and resume, if necessary, the following winter. In addition to special trucks that vibrate the ground, the effort would include movable fuel tanks as well as housing and other facilities for two crews of 160 workers each. In the plan, the company said it and its partners were “dedicated to minimizing the effect of our operations on the environment.”

By producing three-dimensional images of the subsurface, the testing would help oil companies determine whether there are enough reserves to make it worth buying leases to drill in the area.

The plan drew criticism from the United States Fish and Wildlife Service when it was first put forth in May. But another agency of the Interior Department, the Bureau of Land Management, will review the plan and decide whether to allow testing. Lesli Ellis-Wouters, a bureau spokeswoman, said that SAExploration had been asked to provide more information.

The approval process includes conducting an environmental assessment, a less-thorough appraisal than an environmental impact statement, or E.I.S., although the bureau can require an E.I.S. later if the initial review finds the work could result in significant impacts.