A Framework for Building New Desert Science
By Don Comis
May 24, 2007
Agricultural Research Service rangeland
Herrick has joined with scientists from around the world to develop a
template for a new desertification science that incorporates human as well as
biological and physical dimensions.
Herrick is at the
Jornada Experimental Range near Las Cruces, N.M. The experimental range
includes 193,000 acres of rangeland in the Chihuahuan Desert.
Herrick and colleagues in environmental and social sciences from around the
world have written a paper on the subject entitled "Global
Desertification: Building a Science for Dryland Development." It was
published earlier this month in Science magazine.
The researchers introduced the Drylands Development Paradigm (DDP), named
for a 2001 workshop in Berlin, Germany, from which the original framework for
solutions to desertification was developed.
Two of the principles of this framework have guided ARS work at the Jornada
for many years: that slow variables determine what happens on arid lands, and
that these slow variables are often associated with tipping points or
thresholds that, if crossed, can rapidly lead to irreversible change.
Experience at the Jornada taught Herrick that arid regions work on
"desert time," in which recovery is often initiated by rare events,
like unusually large rainstorms. One of the ways this knowledge can be used is
by staking seed-filled plastic pipes in dry rills. When rain comes, runoff
flows through the pipe, depositing seeds under a layer of litter
mulch and beginning the slow process of vegetation recovery.
Experience also taught Herrick that natural ecological processes dictate
that once a thresholdsuch as too much weedy brush growthis reached,
it can be very difficult to reverse.
Part of the DDP involves integrating local and scientific knowledge to
anticipate thresholds long before they are reached, while they still can be
It is a framework for actions to support the
United Nations' efforts to combat
desertification worldwide, recognizing that about 250 million people in the
developing world live in arid lands with some form of severe land degradation.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.