••
••
Surface disturbances destroy biocrusts and
they take a LONG time to grow back
The replacement of in-tact biocrusts with bare ground
or early successional biocrusts influences local and regional hydrology
~1860
~1000 BC
~3000 BC
~1920
~1000 BC
~1850
~1920
Pacific Railway Act - 1862
Taylor Grazing Act - 1934
Neff, J. C., et al. "Increasing eolian dust deposition in the western United States linked to human activity." Nature Geoscience 1.3 (2008): 189
Porphyry Basin tarn sediments
5-7x increase in deposition of K, Mg, and Ca (peaking in early 1900s)
5-10x increase in N and P, mostly since ~1950, (not peaked)
Lakes in the San Juan Mountains, Colorado
Al
Ca
K
PN
(Neff et al. 2008 Nature)
•••
•••
Dust
Clean
Nat
ural
ized
Run
off
(BC
M/d
ay)
Mexico’s annual allotment
LV
LA
* Based on pre-2009 dust loading
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•
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