Last updated: April 18, 2025
Article
Species Inventory Explores Visitor Impact on Cave Lichens at Lava Beds National Monument
By Christina Martin, I&M Research Scientist and Communication Specialist
October 2024
At Lava Beds National Monument (NM), a species inventory is helping park managers understand the rich diversity of lichens in the park, allowing them to craft management strategies to preserve them.
Roughly 100,000 people visit the caves of the monument each year, yet little is known about how visitors may impact lichen abundance and diversity. To effectively protect these resources, park managers need to know which lichen species inhabit the park’s caves and whether their presence varies between sites with low and high visitor use.
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Lichens are made up of fungi and algae or bacteria that work together to survive. This mutual support allows lichens to thrive in various environments, from rocky surfaces to tree bark. In dry ecosystems, caves provide critical habitat for lichens, offering moderately moist, mild climates in otherwise harsh landscapes. At Lava Beds NM, located in a semi-arid zone of northern California, cave lichens represent a unique floral component for the region, and include many rare or little-known species.
To better understand the patterns of diversity and potential visitor impacts on these organisms, the National Park Service’s Inventory & Monitoring Division arranged for a lichen inventory and visitor use study. Surveyors explored 42 caves in the monument across a range of visitor use.
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They uncovered a total of 211 different lichens, 27 of which had never been documented in the monument. With these new records, the total number of known lichen types in the park rose to 288. Ice caves were found to host many rare lichens, and caves with deeper entrances and larger sink areas support a greater diversity of lichens.
Encouragingly, the study found no significant difference in lichen diversity between caves with high and low visitor use. Researchers suggest that infrastructure, such as railings and stairways, may help minimize visitor impacts. While lichens may still experience localized damage from trampling or scraping, these effects do not appear to reduce diversity on a broader, landscape-level scale.
This inventory confirmed that the caves in Lava Beds NM provide vital habitat for a wide range of lichens and expanded what we know about these unique organisms. It also gave park managers a clearer picture of how visitor activity affects these species, offering valuable insight for future planning and protection efforts. Visitors can help further protect lichens by staying on designated trails and being mindful of where they step and touch.