New Study: Yosemite National Park History Tells Story of Loss and Protection

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On the eve of the 100th anniversary of the National Park Service, a new study led by Conservation International sheds light on the impacts of the loss of legal protection in one of oldest and most iconic parks in the U.S.

On the eve of the 100th anniversary of the National Park Service, a new study reveals the environmental legacy of legal changes to Yosemite National Park’s boundaries early in the Park’s history. Driven to enable natural resource extraction, Yosemite National Park was reduced by 29.8 percent between 1905 and 1937, according to a study published this week in the journal Ecology and Society. The study was led by a team of scientists from Conservation International, George Mason University and Clark University, as part of a broader CI research initiative to investigate the patterns, trends, causes and consequences of protected area downgrading, downsizing and degazettement (PADDD).

When it was established in 1890, Yosemite covered an area of 1,500 square miles (3,886.10 square kilometers). In the next several decades, Yosemite’s boundaries shifted seven times: five small parcels were added and two large tracts of land were removed. Overall, Yosemite’s size was reduced by 29.8%. (505.5 square miles; 1,309.3 square kilometers). Today, the forests that were removed from the park are more highly fragmented by roads than forests which remain protected. The study also found, however, that PADDD is reversible. Certain pieces of land that were removed from Yosemite were re-protected as wilderness areas – these places host more contiguous habitat.

“Over a century ago, Yosemite was set aside to be protected in perpetuity. Since then, protection has been maintained for some of it but not for all,” said Rachel Golden Kroner, a PhD candidate at George Mason University and lead author of the study. “The 100th anniversary of the National Park Service provides an opportunity to reflect on ‘America’s Best Idea.’ Recognizing the impermanence of national parks and other protected areas reminds us that we should not take these national treasures for granted.”

The authors and their colleagues have documented PADDD globally. Mike Mascia, study co-author and senior director of social science at CI’s Moore Center for Science, first coined the term “PADDD” and has been working with colleagues around the world to document this largely overlooked phenomenon since 2009. Their work is captured on, a crowd-sourced website that Mascia and colleagues launched to both document and disseminate information about PADDD.

United States national parks are widely perceived as sacrosanct, but legal changes to Yosemite’s boundaries demonstrate that the USA is not immune to PADDD. “As we look ahead to the future of national parks in the USA and around the world, the history of Yosemite demonstrates the critical importance of protection and the lasting legacy of when protection is lost,” said Mascia. “Environmental policies must account for the fact that we not only can create national parks, but we can also take them away—and when we do take away protection, there can be lasting consequences.”

Mascia stressed that if appropriate policies are not in place, PADDD could happen under the radar, resulting in the loss of natural heritage and the services protected areas provide for climate and other ecosystem services. Though it has been widely documented, the rate of PADDD remains unclear, as do the impacts on biodiversity and ecosystem services. But we do know that parks around the world are currently facing many of the same challenges that Yosemite faced 100 years ago, including demands for resource extraction, road development and other human activities. For example, protected areas along the US southern border (within 100 miles of the Mexico border), including Saguaro and Big Bend National Parks, may be downgraded to allow infrastructure construction for border security purposes. And in Brazil, Iguaçu National Park and Dunas de Natal State Park were recently proposed to be PADDDed to allow highway construction, Emílio Einsfeld Filho Private Natural Heritage Reserve was recently proposed to be downsized to allow dam construction, and Amapá State Forest was recently proposed to be degazetted to allow industrial agriculture.

About Conservation International
Conservation International (CI) uses an innovative blend of science, policy and partnerships to protect the nature people rely on for food, fresh water and livelihoods. Founded in 1987, CI works in more than 30 countries on six continents to ensure a healthy, prosperous planet that supports us all. Learn more about CI and the "Nature Is Speaking" campaign, and follow CI's work on Facebook, YouTube and Instagram.

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