Building upon Traditional Knowledge to Enhance Resilience of Soils in Sub-Saharan Africa - Principles of Sustainable Soil Management in Agroecosystems - page 127

degradative forces. The conventional agriculture system is exposed to stressors. The
general trend of such a system shifts from vulnerability to resilience that survives
the disturbance and adaptation following a disturbance. The conventional view of
resilience predicts that these shifted or “degraded” systems should be more vulner-
able to external stressors. A conventional approach depicts the potential relationships
between soil ecosystem state and the strength of disturbances; natural communities
are highly resilient to degradative forces, that is, the tipping point ( Figure 5.4 , block
circle), leading to an alternative ecosystem state that is far to the right and attained
only at high levels of stress (Donner 2009). As anthropogenic disturbances persist,
gradually degrading the original soil system (light block arrows), the tipping point
in response to degradative forces gradually shifts to the left, making the soil system
less resilient to degradative forces. Thus, management that controls local stressors to
reverse degradation and recover the original condition of soil may actually increase
the vulnerability of the soil system and may effectively decrease soil system resil-
ience to external disturbance and climate change (Jupiter et al. 2008). A counter-
intuitive model implies that protected or more conserved soils will cross a tipping
point and subsequently shift into an alternative adaptive state, but other alternative
states are possible (Coelho and Manfrino 2007)—only at high levels of climate dis-
turbance (Figure 5.4). As nonclimatic, local disturbances degrade the original eco-
system (Figure 5.4, dark block arrows), the tipping point, in response to external
stressors and climate change, shifts to the left (Figure 5.4), making the ecosystem
less resistant. Management that seeks to control local stressors and reverse degrada-
tion (Figure 5.4, black block arrows) is therefore expected to increase resilience by
shifting the tipping point back to the right and keeping soil climate disturbance.
Using TK, farmers may protect fragile soils and leave less sensitive soils unprotected
or under conventional systems of production.
5.4.3 a lternatIve v IeW to m anagIng For r esIlIence
The postulation that protected systems should be more resilient to disturbances from
external forces is poorly supported by empirical evidence pertaining to resistance
and recovery (Rachello-Dolmen and Cleary 2007). With this perspective, we argue
that the expectation of increased resilience of soil to external stressors and climate
change through the reduction of local stressors may be fundamentally incorrect and
that a conventional approach to resilience may, in fact, result in greater vulnera-
bility to degradative forces and climate impacts. The alternative view of resilience
encompasses two separate processes: resistance (the magnitude of disturbance that
causes a change in structure) and recovery (the speed of return to the original struc-
ture), which are fundamentally different but rarely distinguished (Schoon 2005). If
the tolerance of a soils system to a nonclimatic disturbance is correlated with its
tolerance to external and climatic impacts, that is, positive cotolerance (Hughes et
al. 2003), then degradation can actually increase the resilience of a soil within an
ecosystem (Tenywa et al. 2001; Fenton et al. 2007) and thus the ability of the sys-
tem to resist the impacts of anthropogenic and climate disturbance. Anthropogenic
disturbances gradually degrade the soil; the tipping point in response to degradative
forces gradually shifts to the left, making the system less resilient (West and Salm