Editor's note: The following column was written by Deny Galvin, who served 38 years with the National Park Service, including many years as its deputy director.

A soaring new 3D IMAX film premiered recently, showcasing the wonders of national parks from Katmai in Alaska to Everglades in Florida. Narrated by none less than Academy Award® -winner Robert Redford, the film was created by the National Park Service and Brand USA in honor of the Park Service’s 100th anniversary and is airing here and in 60 countries around the globe. Intended to showcase the best of our nation, the film falls woefully short as critics have pointed out, because it features only athletic, young white Americans recreating in pretty places. But our nation, if nothing else, is diverse. The National Park Service, as the first and leading conservation steward in the world, should be a model for how to protect our diverse heritage and reflect, engage and honor all people.

I worked for the National Park Service for 38 years. My heroes were American conservation pioneers like John Muir, Teddy Roosevelt, John Burroughs, Gifford Pinchot, John Wesley Powell, and Henry David Thoreau. They inspired and created a means of protecting unique landscapes, which has since been adopted around the world.

These gorgeous landscapes, especially those featured in the IMAX film, are wonders of creation. People come from around the world to see Yosemite, Yellowstone, Death Valley and the Great Smoky Mountains. Attendance has been increasing every year – so clearly, the National Park Service is doing something right. In fact, surveys repeatedly show that park rangers are among the most trusted and beloved of all government employees.

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But as with any great endeavor, there are always next steps and more to be accomplished. As America changes, so must the National Park Service and our system of parks and public lands. “America’s best idea” needs to evolve and become our most “innovative idea.” American conservation in its second century cannot be a hobby of the few if we are to confront the urgent environmental, health and ideological threats to our communities, and to our shared heritage.

When President Obama celebrates the National Park Service Centennial on August 25, 2016, he should take credit for how his Administration has taken unprecedented steps to broaden the diversity of our system of parks and public lands. But he should also seize this opportunity to challenge America in its second century of conservation. We need to again lead the world by showing how and why it matters that our parks and public lands reflect, honor and engage our nation’s entire people.

The National Park Service needs to recruit and retain talent from diverse communities – and not just for internships but full-time positions. The agency needs to broaden the partners and stakeholders it engages in policy issues, from interpretation to cultural resource preservation and landscape-scale conservation. And we need to take a closer look at the sites and stories told in our system to ensure it reflects the nation. We need to make a serious effort to transform the park system to better reflect America’s diversity and values.

We are living at a time of rich growth potential for our national parks, as we enter a second century for what is the most admired park system in the world. I see almost unlimited opportunities for growing the National Park System in step with coming generations.

Deny Galvin served 38 years with the National Park Service, including many years as its deputy director. He is a member of the Coalition to Protect America’s National Parks -- an organization of over 1,100 former employees of the National Park Service with over 30,000 years of experience in managing parks and park programs.