With
sizzling temperatures and a
parched climate, it can be
hard to survive in the
Sonoran Desert of Arizona.
But some species have
evolved to thrive in this
extreme environment,
including the iconic saguaro
cactus. Part of the reason
for this prickly plant’s
success is its intimate
relationship with a
smaller—but similarly
mighty—desert player:
fungi.
A
team of researchers is
working to uncover the
mysterious symbiotic
relationship that
mycorrhizal fungi have
formed with the cacti, which
are increasingly threatened
by climate change and urban
development. My colleague
Wyatt Myskow, ICN’s
Southwest reporter, recently
joined a few of these
researchers on a trip to the
Sonoran Desert to see this
effort firsthand. I asked
Wyatt to tell me more about
his experience covering the
secret
lives of cacti and fungi—and
the compounding risks they
face.
How
did you learn about this
story?
The
researchers actually reached
out to me first. I’ve been
covering public lands and
wildlife in Arizona and the
Southwest for years and have
written about the struggles
the saguaro cactus faces
because of climate change in
the past. They had seen my
coverage and reached out to
see if I was interested in
joining them in the
field—which I can never say
no to.
You
say that the arid deserts
like that in Saguaro
National Park can be
unforgiving. Can you
describe this type of
ecosystem more and how the
fungi and cacti interact
to survive it?
Saguaro
National Park is found just
outside of Tucson, Arizona,
which is in the heart of the
Sonoran Desert.
Unsurprisingly, it’s a hot
and dry place, getting
around 12 inches of rain a
year and summer temperatures
exceeding 100 degrees
Fahrenheit. But unlike some
other deserts, like, say,
the Mojave where I grew up,
it’s much greener in large
part due to it being wetter.
In the Sonoran Desert,
creosote bushes, an
assortment of cacti and palo
verde and mesquite trees
dominate the landscape, and
the saguaro cactus towers
above them all.
We
know lots of things about
the Sonoran Desert and
saguaros: The cactus is a
keystone species, meaning
it’s vital to the ecosystem;
they can live for centuries
and don’t mature until they
are around 100 years old;
their fruits and flowers
have helped sustain life in
the region during the
hottest time of the year,
when the rest of the desert
is brown and crispy.
We
know mycorrhizal fungi live
in the soil—and we know
those fungal systems help
create highways of nutrients
to plants they support,
trading water and nutrients
like nitrogen and phosphorus
in exchange for carbon. But
we don’t know much about the
exact mycorrhizal fungi
found living in the soil
with saguaros and how they
support the iconic cactus
species.
What
was your reporting trip
like? Is there anything
that didn’t make it into
the story that you can
share?
I
drove down from Phoenix
early to meet with the
researchers on the east side
of the park, which borders
the Rincons, one of the
mountain ranges that
surround Tucson. On the
other side is perhaps my
favorite place on Earth, my
beloved San Pedro Valley.
The researchers were—and I
hope the story conveys
this—just a blast to spend
the day with.
We
tasted the dirt to see if we
could taste the fungi (in
this case, it just tasted
like dirt) and hiked
beautiful desert hillsides
that look like a forest made
out of saguaros. The process
itself was fairly simple:
They collected soil samples
to test at the lab and took
measurements of the
saguaros. That night I
camped, and the next morning
I headed out to Mammoth to cover
a copper mine coming
into the region that’s
threatening the area’s
scarce water supply.
It’ll
be some time before we have
results from the
researchers’ expedition. But
not long after the story
came out, the group
they are with, the Society
for the Protection of
Underground Networks (SPUN),
published
a study that for the
first time mapped global
mycorrhizal fungal networks.
The study found that more
than 90 percent of fungal
communities are unprotected,
threatening their ability to
draw down carbon and support
ecosystems across the globe.
What
threats do the saguaros
face?
Saguaros,
like most desert species,
are incredibly resilient,
able to withstand years of
drought and extreme
temperatures. But climate
change is pushing even them
to their limits, and often
past it.
Higher
temperatures, drier
landscapes, human
development, bigger and
hotter wildfires and
invasive species—which can
outcompete saguaros by
growing quickly and fueling
fires that kill native
vegetation—are all major
threats the species is
facing. In recent years,
thousands have died.
In
Phoenix, where I live,
recent summers have left
saguaros in people’s yards
falling over dead from the
extreme heat. Ecologists who
study saguaros have told me
the species in many areas
will not recover, though
they aren’t at threat of
becoming endangered yet.
One
of the more recent threats,
and a big theme of the
story, is that protected
areas that serve as refuges
for saguaros and other
species are under threat
from the Trump
administration. National
parks across the country
have less funding and staff,
slashed by the current
administration.
The
administration is also
looking to downsize and
eliminate some national
monuments, which are
basically the little
siblings of national parks.
Many of those targeted are
found in Arizona, like
nearby Ironwood
Forest National Monument,
which is threatened for
downsizing to allow a nearby
copper mine to expand.
Protected areas like these
are increasingly uncommon
around the world as habitat
is disrupted to make way for
human developments.
How
can this effort to
increase studies on fungi
help?
Right
now, how fungi help saguaros
is just a black box. We
don’t know how exactly they
interact and how beneficial
they might be in the
species’ survival, something
that will only become more
important as the Sonoran
Desert is continually
affected by climate change.
This study can help change
that. As one of the
researchers told me, “Once
it’s gone and deleted, it’s
gone. The thing that upsets
me is, if they’re gone
before we actually know
what’s there, we have no
idea what we’ve lost. That’s
an immeasurable loss to
humanity.”
Note:
There’s no “More Top
Climate News” this week
because I am on vacation!
See you next week.
Postcard
From … Arizona
Obviously,
I had to ask Wyatt to send
us some photos from his
adventures with the
researchers studying the
cacti and fungi. Here’s what
he said:
“I
spent the day in the field
with Jinsu Elhance and
Justin Stewart (as seen left
to right in the top photo),
researchers with the Society
for the Protection of
Underground Networks. Though
the science to understand
the fungi’s connection to
saguaros is complicated,
getting the samples in the
field is not. All they
needed was a cylinder and a
mallet to get soil samples
and test tubes to put them
in.
“As
the two collected samples,
they also collected data on
the saguaros themselves.
Mature saguaros can get
pretty tall, so they used
ladders to get to the top.
From there, they used their
phone’s LiDAR (who knew
phones could be so
technologically advanced?)
to create a 3D image showing
how tall the cactus is and
how many limbs it features,
allowing the researchers to
estimate its age.”
