President Donald Trump announced a freeze on all federal hiring, eliminating any vacant positions and prohibiting the creation of new positions as of noon on Jan. 22. The presidential memorandum will affect all federal agencies except the military, and includes land management employees. It follows on the heels of another announcement that U.S. Department of Agriculture and Environmental Protection Agency grants and contracts will be frozen.

Trump’s memorandum seeks to cut back the number of federal employees by an unspecified amount. In 2015, the Business Insider analyzed Bureau of Labor Statistics and found federal employee numbers to be the lowest in 54 years.

The memorandum did not make allowances for seasonal hires, a necessity for agencies like the National Park Service and Forest Service, which hire thousands of short-term rangers and other employees nationwide during the summer months.

In an interview with the Missoulian newspaper, Melissa Baumann, council president of the National Federation of Federal Employees, said she did not know how this would impact the hiring of wildland firefighters. According to Baumann, the Forest Service hired 11,000 seasonal workers in 2015, many of them to fight the Western wildfires that break out between June and September. According to National Parks Traveler, the National Park Service is going ahead with identifying potential new seasonal hires in hopes that a waiver will be granted for some workers.

A representative for the Forest Service said, “The U.S. Forest Service is waiting for further clarification and direction from the Office of Personnel Management related to the hiring freeze. We cannot speculate on the impact of the hiring freeze.

Managers are seeing an increase in public use of the millions of acres they manage, and are struggling to keep up.

“(National parks) cannot continue to be hampered by low staffing, and that’s exactly what will happen with this hiring freeze,” Theresa Pierno, president and CEO of National Parks Conservation Association, said in a press release. “Park rangers are already forced to do more with less because they don’t have enough staff to handle record-breaking crowds.”

The memorandum made allowances when hiring for “national security,” but it is unclear what that would mean, and if needs like hiring firefighters for the massive wildfires that are sure to hit the West would count. It included that contracting outside the government would not be allowed.

The hiring freeze is also antithetical to Trump’s campaign goals of increasing American jobs and energy production on public lands – something that would require more staff, not less. A recent survey from Public Employees for Environmental Responsibility showed that staffers at the Bureau of Land Management, where oil and gas exploration primarily occurs, already can’t keep up with current permitting responsibilities.

The hiring freeze comes as part of Trump’s campaign promise to cut down on federal oversight. Press secretary Sean Spicer framed it as a responsibility to American taxpayers, saying “to see money get wasted in Washington on a job that is duplicative, is insulting to the hard work that they do to pay their taxes.”

The vast majority of the affected positions would not be in Washington, D.C. A 1982 report by the Government Office of Accountability that reviewed four across-the-board federal hiring freezes under the Carter and Reagan administrations, found they are not effective at reducing the size and cost of the federal workforce. Instead they “provided an illusion of control on federal employment and spending,” but end up setting agencies back, as they do not account for agency-specific needs and workload. For example, the report found the 1980 freeze under Reagan hampered the ability of the Interior Department to effectively monitor the Trans-Alaska Pipeline, as two important positions went unfilled. The report also suggested finding specific parts of government agencies to cut back, rather than a widespread freeze. It also found the Office of Management and Budget did not actually quantify how much money, if any, was saved by the freezes.

It’s unknown how long the freeze will last, or what direct repercussions it might have. According to the memorandum, the Office of Management and Budget will come up with a long-term plan within 90 days to continue reducing the number of federal workers.