Using Plants to Protect the Past

The “Western” definition of wilderness often describes vast landscapes free from human manipulation, but this definition forgets that humans are animals; we are a part of the ecosystem. For thousands of years humans have influenced the migratory patterns of animals and altered the plants on the landscape through fire, livestock grazing, and farming. Humans have been on this planet for thousands of years, and we have made our mark –sometimes for the better and sometimes for the worse. In a new study from the University of Utah, researchers combine archeology, ecology, and Indigenous culture to understand how tribes living on the Colorado Plateau shaped the environment today. Instead of trying to revert the ecosystem back to its “pre-human” state (which is unknowable) the study suggests we should think about the role humans have on our landscapes and work to conserve that history.

The study occurred in Bears Ears National Monument in Southeastern Utah. President Obama designated this National Monument to preserve the many archeological sites scattered throughout the area. Dr. Bruce Pavlik and his collaborators wanted to know if these archeological sites also held a history of human influence on the plant community. Specifically, they were searching for plants that were valued by the people who inhabited Bears Ears. The researchers identified five tribal groups in the area (Navajo, Hopi, Zuni, Ute Mountain Ute, and Apache) and 117 plant species that are significant to the tribes. To learn more about the tribal land and see the tribal land you live on, check out the Native Land Map.

Of the 117 plant species, 31 were more common near archeological sites compared to the surrounding landscape. Many of these plants produce roots, fruits, and seeds that are important for food, medicine, and ceremonies. When the archaeological sites were larger and contained more manmade structures, the researchers found more plants that were significant to the tribes. Many of these plants thrived in the ecosystems created by human civilizations. Humans lived in areas near resources that plants also need to survive in the cold desert of Bears Ears, like near water and shelter. The humans benefited from the plants and plants seemed to benefit from the humans.

One of these important plants is the Four-Corners Potato, an important food source for many tribes in the region. Interestingly, the plant was found at seven archeological sites, all of which were outside of its known climatic range. This suggests that the tribes were creating an environment to cultivate this species in an area where it would not ordinarily live. These potatoes can stay underground for up to 14 years and therefore considered a reliable food source in the harsh winters and springs. This also means that researchers should update models of where this species can live and consider the role of archaeological sites in its persistence.

From this study we learned that historical human behavior could influence the ecology of today, and that’s not necessarily a bad thing. Humans are part of the ecosystem, and this study demonstrates one of the many ways humans change the environment around us. These plants are an ecological legacy, culturally significant, and should be protected. Future work should focus on documenting culturally significant plants, protecting their habitat, and educating the public about the historic role humans played in shaping this unique landscape. Traditional ecological knowledge from the tribes that have been living on this land for centuries should be incorporated into management decisions and we should all work together to preserve their ancestral lands.

Source: Pavlik, B., Louderback, LA., Vernon, KB., Yaworsky, PM., Wilson, C., Clifford, A., and Codding, BF. Plant species richness at archaeological sites suggests ecological legacy of Indigenous subsistence on the Colorado Plateau. 2021. PNAS 118(21): e2025047118.

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Brianne Palmer

I am a PhD candidate at San Diego State University and the University of California, Davis studying how biological soil crusts respond and recover from fire. Most of my research is in coastal grasslands and sage scrub. We use DNA and field measurements to understand how cyanobacteria within biological soil crusts help ecosystems recover after low severity fires. I am also involved with local K-12 outreach within the Greater San Diego Metro Area.

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