Science News - USA (2022-06-18)

(Maropa) #1
http://www.sciencenews.org | June 18, 2022 13

FROM TOP: B. WEBER; RAFFI MAGHDESSIAN/AURORA OPEN/GETTY IMAGES PLUS


quality, hasten glacier melting and reduce
river flows. For instance, in the Upper
Colorado River Basin, researchers have
found that dust not only decreases snow’s
ability to reflect sunlight, but it also short-
ens the duration of snow cover by weeks,
reducing flows of meltwater into the Colo-
rado River by about 5 percent. That’s more
water than the city of Las Vegas uses in a
year, says Matthew Bowker, a soil ecologist
at Northern Arizona University in Flagstaff
who wasn’t involved in the new study.
Experiments had already shown that
biocrusts strengthen soils against erosion,
but Weber and colleagues were curious
how that effect plays out on a global scale.
They pulled data from experimental stud-
ies that measured wind velocities needed
to erode dust from various soil types and
calculated how differences in biocrust
coverage would affect dust generation.
The wind velocities needed to erode dust
from soils completely shielded by bio-
crusts are on average about five times
as high as the wind velocities needed to
erode bare soils.
The researchers incorporated these
results, along with data on global biocrust

coverage, into a global climate simulation
to estimate how much dust the world’s
biocrusts trap each year.
“Nobody has really tried to make that
calculation globally before,” Bowker says.
“Even if their number is off, it shows
us that the real number is probably
significant.”
Using projections of future climate
conditions and data on the conditions
biocrusts can tolerate, Weber and col-
leagues estimate that by 2070, climate

change and land-use shifts may result in
a roughly 25 to 40 percent reduction in
area covered by biocrusts globally, which
would increase global dust emissions by
about 5 to 15 percent.
Preserving and restoring biocrusts will
be key to mitigating soil erosion and dust
production, Bowker says. Hopefully, these
results will help to whip up more discus-
sions on the impacts of land-use changes
on biocrust health, he says. “We need to
have those conversations.”

Lichens (whitish-pink) and cyanobacteria (dark brown to blackish) form biocrusts that carpet
the ground between succulent plants and shrubs in South Africa’s Succulent Karoo ecoregion.

LIFE & EVOLUTION
Headbutts hurt musk ox brains
Punishing headbutts damage the brains of musk oxen. That
observation, reported May 17 in Acta Neuropathologica,
suggests that a life full of bell-ringing clashes is not without
consequences, even in animals built to bash.
When charging, a musk ox can reach speeds of up to
60 kilometers an hour before ramming its head directly into
an oncoming head. The assumption was that musk ox brains
could withstand these forces largely unscathed, says neuro-
scientist Nicole Ackermans of the Icahn School of Medicine

at Mount Sinai in New York City. “No one actually checked.”
In fact, the brains of three wild musk oxen (two were fe-
male and one was male) showed signs of extensive damage,
Ackermans and colleagues found. The damage was similar to
what’s seen in people with chronic traumatic encephalopa-
thy, a disorder caused by repetitive head hits. In the musk ox
brains, a form of a protein called tau had accumulated in
patterns that suggested brain bashing was to blame.
In a twist, the brains of the females, which hit heads less
frequently than males, were worse off than the male’s brain.
The male body may cushion blows better with its heavier
skull, stronger neck muscles and other protective features.
The results may highlight an evolutionary balancing act:
Musk oxen can endure just enough brain damage
to allow them to survive and procreate.
High-level brainwork may not matter
much, Ackermans says. “Their day-to-
day life is not super complicated.”
— Laura Sanders
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