New Research Opportunities in the Earth Sciences - New Research Opportunities in the Earth Sciences - page 67

Figure 2.20 Illustration of the effects on soil moisture-vegetation feedback on vegetation
patterns in a dryland ecosystem. (a) and (b) Alternate stable states (solid lines) and unstable
states (dashed lines) of vegetation biomass; R is annual rainfall in millimeters, and arrows
indicate convergence toward a stable state. The thin lines in (b) show stable states under
randomly varying rainfall conditions characterized by the indicated coefficients of variation
(CV). (c) Noise-induced patterns of vegetation cover ( f = fraction covered) for varying
precipitation conditions ( P is the probability of no water stress). Vegetation patterning occurs
at intermediate precipitation conditions when stressed and unstressed states alternate but not
for lower or higher values of P . SOURCE: D'Odorico et al. (2010b).
Role of Humans in Landscape Change
Recognition that people are now one of the dominant forces shaping Earth's
surface has opened new areas in the study of recent (i.e., historical) environmental
records and in forecasting the effects of future population growth and development on
environmental systems and landscapes. There is growing societal recognition that the
geomorphological impacts of human land use have shaped ancient societies and
continue to do so today, from the role of marsh destruction in exacerbating hurricane
impacts on coastal cities to the erosion of the soil in which food is grown.
In many parts of the world, society's reaction to landscape disturbance is an
engineered response: dams and levees to mitigate floods; groins and breakwaters to
slow coastal erosion; various forms of hill slope stabilization to limit landslides; and
more recently, restoration of rivers and wetlands that have been impaired by human
activities. The frequent failure of these interventions to accomplish their goals and/or
the unintended consequences of these engineered solutions highlight the critical need
for better scientific understanding of the underlying processes and ability to predict
the success and impacts of proposed solutions. The National Center for Earth-Surface
Dynamics (NCED), an NSF Science and Technology Center, hosted at the University
of Minnesota, is developing leading advances in the science and practice of stream
restoration by conducting and coordinating research directed toward multidisciplinary
quantitative prediction and development of improved tools to transfer this knowledge