Three-quarters of the members of the National Park System Advisory Board, a group that advises the National Park Service, quit on Monday evening. In a letter informing Interior Secretary Ryan Zinke of their decision, they said Zinke and his staff’s refusal to meet with them spurred the decision.

“From all the events of this past year I have profound concern that the mission of stewardship, protection, and advancement of our National Parks has been set aside,” the letter, written by departing board chair Tony Knowles and signed by eight others, and published by the Washington Post, reads. “I hope that future actions of the Department of Interior demonstrate that is not the case.”

First authorized in 1935 under the Historic Sites, Buildings, and Antiquities Act, the National Park System Advisory Board is a bipartisan, 12-member group that advises the federal government on how to manage the United States’ national parks. All the signatories of Monday’s letter had terms set to expire in May.

In Knowles’s letter, he notes the advisory board’s work in engaging national experts in education, science, history, and anthropology, and taking part in park management and planning “to help design the right path to meet the challenges and changes for the second century of our National Parks.”

He said the group “emphasized scientific research and mitigation of climate change” as well as “evolving a more diverse culture of park visitors” and “protecting the natural diversity of wildlife,” among other initiatives, and sought to meet with Zinke and his staff about their agenda to brief them on their activities.

“We understand the complexity of transition but our requests to engage have been ignored and the matters on which we wanted to brief the new Department team are clearly not part of its agenda,” Knowles wrote. “I wish the National Park System and Service well and will always be dedicated to their success.”

As NPR points out, Alaska Public Radio quoted Knowles as saying the Interior Department “showed no interest in learning about or continuing to use the forward-thinking agenda of science, the effect of climate change, protections of the ecosystems, education.” He also noted that it has rescinded regulations concerning biodiversity loss, pollution, and climate change.

Secretary Zinke, formerly a US representative serving Montana, has come under scrutiny for promoting the president’s agenda over protection the nation’s public lands. Per the New York Times:

This month Mr. Zinke announced a plan to open up the majority of the nation’s coastlines to offshore drilling. And in December, the administration reduced the size of two national monuments in Utah, Bears Ears and Grand Staircase-Escalante, by some two million acres, the largest rollback of federal land protection in the nation’s history.

Zinke also raised eyebrows when a small company from his hometown of Whitefish, Montana, was awarded a $300 million contract to repair Puerto Rico’s power grid after Hurricane Maria. After coming under scrutiny, the contract was canceled.

Three board members did not resign: Harvard University public finance professor Linda Bilmes, University of Maryland marine science professor Rita Colwell, and Project Concern International chief executive Carolyn Hessler-Radelet, according to the Post. Bilmes’s and Colwell’s terms end in May, and Hessler-Radelet’s ends in 2021.