U.S. Water News Online
LAS CRUCES, N.M. -- Getting down to the "root" of studying
desert plants can survive for months without rain, U.S. Department of Agriculture
scientists are using a backhoe to dig 15-foot trenches beneath the surface of
arid rangeland near Las Cruces. Using ice picks and high-pressure water
sprays, the researchers are exposing root systems that provide clues to the
plants' drought defenses.
In determining how some desert plants survive with the scant water
searing heat that would kill most other vegetation, "we've seen plants
equipped with a survival mechanism that overrides the natural tendency for
plants to send roots downward towards water," said rangeland scientist Robert
Gibbens of the Agricultural Research Service. "That's good because roots near
the surface can get moisture from light rainstorms," added Gibbens.
Desert plants thus can receive moisture from two soil depths, he
this helps explain why shrubs have successfully invaded -- and now dominate
-- many areas that were once desert grassland." The federal researchers have
actually found some roots of desert shrubs growing upward, fanning out to
collect water from rainstorms. Conversely, Gibbens pointed out, "we've
uncovered mesquite shrubs that have one big root that can grow downward --
deeper than our trenches -- to tap underground water."
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