Wildfires Affect Cave Diversity Underneath Scorched Surfaces
Portland, Ore., USA: The landscape at Lava Beds National Monument in northern
California is typically home to sage and junipers, with unique lava caves
twisting underneath the surface. But in the summers of 2020 and 2021,
wildfires tore through the region, burning thousands of acres and leaving
the surface charred.
The fires that scorched the surface also impacted life in the caves below,
according to
new research
that will be presented at the Geological Society of America’s GSA Connects
2021 annual meeting on Monday in Portland, Oregon.
Healthy caves are fragile ecosystems that host far more than bats: They are
also home to diverse communities of small mammals, birds, insects, and
invertebrates. Cave dwellers can be highly adapted to their niche and
therefore sensitive to any changes to their environment. When a wildfire
intensely burns the ground above a cave, it is reasonable to expect the
cave ecosystem could be affected. And with wildfires affecting larger areas
every year, understanding those impacts has never been more important.
Scientists at Lava Beds had been monitoring ecology in 33 caves for six
years when the Caldwell Fire struck in July 2020, burning around 70% of the
park. The Antelope Fire, which began in August 2021, burned 27% of the
park’s area. “So 97% of the park has burned within the past year,” said
Jordan Kemp, a Scientists in Parks intern at Lava Beds and graduate student
at Indiana State University. The disaster provided a natural opportunity to
study the effect wildfires have on cave ecology.
“We’ve never had a fire like this before, so the worry was, ‘Now that we’ve
lost all this vegetation at the surface, what will happen to life
underneath?’” said Kemp.
Invertebrates like cave millipedes, dipluran, and isopods are small but
have an outsize impact on overall cave health: Disturbances at the bottom
of the food web can ripple up to the top, especially in ecosystems where
many species are highly specialized. Because communities within lava tubes
in caves tend to be isolated, unique species can evolve that are only found
in a few cave environments
.
To answer that question, Kemp and colleagues returned to the caves to see
what damage had been done and to document specimens that had been attracted
to the tiny baits laid for invertebrates. Their preliminary results,
tracking population changes and species diversity, suggest a significant
drop in ecosystem diversity in the caves under surfaces burned by the
Caldwell and Antelope Fires. Those community changes could be driven by
moisture.
“After the fires, we’ve seen wet caves in burn areas become drier, and some
dry caves become wet. Loss of vegetation on the surface could have led to a
change in groundwater flow, and how water is percolating down through the
soil,” said Kemp.
That change in hydrology affected cave humidity, an environmental factor to
which invertebrates can be highly sensitive. The fundamental relationship
between vegetation mediating water flow at the surface and how much
moisture makes it into caves likely holds true for other caves under
fire-affected landscapes. Understanding how fires change caves’ moisture,
and therefore diversity, will help scientists and land managers protect
fragile caves ecosystems as fires become ubiquitous across much of the
country.
The caves at Lava Beds National Monument are also home to artifacts and
paintings of the Indigenous Modoc people, whose ancestral lands the
Monument occupies today. Because invertebrates are so sensitive to overall
cave health, they can be a good indicator for preservation risks to the
artifacts.
Unprecedented Wildfire Season Leaves Lasting Impact on Cave Resources:
A Case Study from Lava Beds National Monument
https://gsa.confex.com/gsa/2021AM/meetingapp.cgi/Paper/368950
Monday, 11 October, 2:20–2:35 p.m.
Oregon Convention Center Room D137
Contact: Jordan Kemp, Lava Beds National Monument and Indiana State
University, jordannicolek@gmail.com
Editor’s note: The views presented here are the individual’s and do not
necessarily reflect the views of the National Park Service.
# # #
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with members from academia, government, and industry in more than 100
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the professional growth of its members and promotes the geosciences in the
service of humankind. Headquartered in Boulder, Colorado, USA, GSA
encourages cooperative research among earth, life, planetary, and social
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levels of earth science education.
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