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WWU researchers document 93% historical loss of persistent, old-growth grasslands in the San Juan Islands

The publication maps one of the few remaining places in Western Washington where remnants of native grasslands persist

by Jennifer Nerad

Office of University Communications

Kailey Schillinger-Brokaw visited Lopez Island in 2022 to meet with local ecologists and conservationists and ground-truth the data used to create maps documenting native grasslands changes in the San Juan Islands. Photo by Aquila Flower.

Native grasslands have shaped the ecological and cultural landscapes of the San Juan Islands for millennia, but the extent of grassland ecosystems has shrunk dramatically since the 19th century.

These grasslands provide vital ecosystem services, including carbon sequestration, soil stabilization, flood mitigation and habitat for rare and endemic species — including the severely endangered island marble butterfly. Coast Salish peoples long maintained many of the islands’ grasslands through cultural burning practices.  

In “Historical Loss of Native Old-Growth Grasslands on the San Juan Islands, Washington,” recently published in the journal Ecologies, researchers from Western Washington University’s College of the Environment collected and analyzed historical land cover data and multispectral aerial imagery. They found that only 7.3% of persistent, old-growth grasslands from the 1890s remain today.

A map shows changes in grassland land cover on the San Juan Islands indicating an overall 77% net decrease in the extent of non-agricultural grasslands and a 93% loss in persistent, old-growth grasslands between 1890 and 2021.

The publication is coauthored by Kailey Schillinger-Brokaw, who earned a master’s degree in environmental studies with a focus on geography and geographic information science in 2023, and Aquila Flower, professor of geography in the Environmental Studies Department and director of Western’s Spatial Institute.

Researchers created a language of visual cues to help classify data from different sources. This image compares how a forested area on Orcas Island in an 1890 hand-drawn map, left, appears as cleared land in a 1932 aerial photograph.

Schillinger-Brokaw and Flower used GIS techniques to extract and integrate data from historical maps, black-and-white aerial photographs from the 1930s, and contemporary multiband aerial imagery. The resulting spatial datasets and maps reveal dramatic land cover changes, amounting to a net 77% decrease in non-agricultural grasslands and a 93% loss in persistent, old-growth grasslands since 1890 across the region.

“In ecology there’s this concept of a ‘shifting baseline,’ where our perception of what is normal shifts over time and we begin to underestimate how much an ecosystem has been degraded,” said Schillinger-Brokaw, who is now a GIS specialist for the New York Natural Heritage Program in Albany, New York. “My hope is that this study can help prevent that from happening to the grasslands of the San Juan Islands.”

Kailey Schillinger-Brokaw, left, and Lamai Larsen (’25) on Lopez Island in 2022. Native grasslands support biodiversity, host endemic species, control erosion, sequester carbon, and are culturally important to Coast Salish peoples. Photo by Aquila Flower.

A mix of pressures has contributed to the loss of native grasslands including agriculture, urbanization, the introduction of non-native invasive species, and the exclusion of fire through active suppression and the banning of traditional cultural burning practices.

The researchers noted their results are likely conservative, as available land cover documentation extends only to 1890, coinciding with the time of widespread Euro-American settlement in the San Juan Islands. By that point, a lot of the region’s native grasslands were already lost.

By documenting the historical extent and distribution of native temperate grasslands in the San Juan Islands, this study creates a resource for effective conservation and restoration practices, and its maps provide an accessible digest of more than 130 years of information.

“Maps help to bridge the communication gap that can occur between scientists and researchers, and the community members and policy makers that need to use scientific knowledge to make informed and ecologically sound decisions,” said Schillinger-Brokaw. “Seeing data represented spatially can make it so much easier to notice the patterns and relationships at play.”

This research was supported by a WWU Graduate Research and Creative Opportunities Grant, enabling Schillinger-Brokaw to visit the islands, meet local ecologists and conservationists, and ground-truth the data in her maps.

Curious where maps can take you? Learn more about degrees in environmental studies, geography and GIS and the Spatial Institute in the College of the Environment. 

Jennifer Nerad covers Western's College of the Environment and College of Business and Economics for the Office of University Communications. Have a great story idea? Reach out to her at neradj@wwu.edu.