Building upon Traditional Knowledge to Enhance Resilience of Soils in Sub-Saharan Africa - Principles of Sustainable Soil Management in Agroecosystems - page 122

5.3.2 a t the s ocIoecologIcal s cale
The resilience approach recognizes that for the social-ecological system (SES), con-
sisting of both human (social system) and nature (ecological), there is no single stable
state, but the system is exposed to different external force “shocks” that challenge its
fundamental identity and make it dynamic. According to Grenville and Riverstone
(2009), one of the major challenges of operationalizing the resilience approach is
defining what constitutes the fundamental structure and function of the system. A
resilient system is one that is able to absorb shocks and adapt without changing
its fundamental structure and function (Gunderson and Holling 2002). Shocks may
be random (e.g., tsunami, land policy reform, major macroeconomic changes) or
cyclical (monsoon), or they may occur at different temporal scales—decadal (e.g.,
drought), annual (e.g., hurricane, labor migration), or finer time scales.
5.3.3 a t the e cologIcal s cale
The ecological concept of resilience recognizes the capacity of an ecosystem to
respond to a disturbance by resisting damage and recovering quickly (Holling 1996).
The disturbances include fires, flooding, erosion, windstorms, insect population
explosions, and human activities such as deforestation and the introduction of exotic
plant or animal species. Disturbances of sufficient magnitude or duration can pro-
foundly affect an ecosystem and may force an ecosystem to reach a threshold beyond
which a different regime of processes and structures predominates (Folke 2006).
Human activities that adversely affect ecosystem resilience such as reduction of bio-
diversity, exploitation of natural resources, pollution, land use, and anthropogenic
climate change are increasingly causing regime shifts in ecosystems, often to less
desirable and degraded conditions (Adger et al. 2005). Ecological resilience and the
thresholds by which resilience is defined are closely interrelated in the way that they
influence environmental policy making, legislation, and subsequently, environmental
management (Holling 1996). The ability of ecosystems to recover from certain levels
of environmental impact is not explicitly noted in legislation; however, because of
ecosystem resilience, some levels of environmental impact associated with develop-
ment are made permissible by environmental policy making and ensuing legislation.
An ecosystem is a biological environment consisting of all the organisms living in
a particular area, as well as all the nonliving (abiotic), physical components of the
environment with which the organisms interact, such as air, soil, water, and sunlight
(Ives and Carpenter 2007). The entire array of organisms inhabiting a particular eco-
system is called a community. Central to the ecosystem concept is the idea that living
organisms interact with every other element in their local environment.
Are degraded communities more susceptible to environmental stressors? There
is increasing recognition by ecologists that, in a variety of ecosystems, species loss
following disturbance is not random. Selective deaths following disturbance have a
direct impact on community structure, by changing the absolute and relative abun-
dances of flora and fauna species (Vinebrooke et al. 2004). Shifts in community
assemblages have been observed following diverse natural and anthropogenic distur-
bances (e.g., pollution, erosion, sedimentation) (Scheffer et al. 2001). Interdisciplinary