Resilience of Socio-Ecological Systems

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Resilience of Socio-Ecological Systems

The previous posts about Kallang Riverside and Bukit Timah reserve left me thinking about the degree of pressure our society exerts on ecosystems. Ecosystems are supposed to be self-maintaining structures that in the absence of outside influences should be able to retain its original structure. Structures such as the existing biosphere and ecosystem services that stem directly from the ecosystem.

Over the last century we have seen a marked change in these ecosystems. Growing human influence on many of these complex ecological systems is the proverbial “wrench” in the work that has the capacity to greatly modify the structure/purpose and capacity of these ecosystems. Take the redirection of rivers to build dams for example. Hydroelectric works in Tibet’s Brahmaputra river effectively change the existing structure of the river. The flow of water along the tributaries downstream of the river could decrease leading to changes in the overall composition of the ecosystems supported by the river (Einhorn, 2016). For example, a loss of habitat for aquatic animals and plants because of the shortfall in water. Thus human intervention in many of the Earth’s ecosystems changes their structure.

Thus it is vital that we understand the concept of ecosystem resilience. Resilience is the processes by which ecosystems maintain themselves in the face of change (Holling, 1973).  Resilience measures the quantum of change or disruption a system can undergo without having to change the controls on its function/structure or state or risk undergoing a fundamental change in its characteristics (Berkes, Colding, & Folke, 2002). It is also associated with the degree to which a system is able to self-organise. Applying this to our earlier example of the Brahmaputra tributaries, the ultimate change in the ecosystems along the river depends on how resilient they are to the change in water levels as a result of human intervention.

Adaptive Capacity

Rather than seeing ecosystems as stable state environments, Berkes et al also proposes the concept of adaptive capacity, where we view ecosystems as evolving structures that have slowly changing variables such as the composition of species. Thus, the term adaptive capacity was coined to encompass the fact that ecosystems are slowly changing and adapting to these changes whilst maintaining a relatively stable state. Crisis only occurs when the degree of external influence overwhelms the adaptive capacity of the ecosystem, when changes are beyond its natural ability to adapt to these changes.

Limitations

Resilience however is largely focused on the ecological aspect of socio-ecological systems. The problem with extending resilience to socio-Ecological Systems is the difficulty in reconciling consciously designed elements in the ecosystem with the original ecosystem structure. Resilience focuses on the natural adaptive capacity of the ecosystem but it is often the case that human intervention seeks to boost the adaptive capacity or resilience of the structures in the ecosystem. Take the Salmon Cannon for example used in Norway; the cannon is meant to provide salmon a means to swim upstream as the river was blocked off by a 350 ft dam (Overland, 2013). By building the cannon, salmon are supposed to have another route to travel upstream with thus minimising the impact that the dam has on the salmon population. Resilience isn’t very useful here such a change hasn’t drastically impacted the process of salmon migration but is a marked change in the flow of the river. Which is why some researcher’s have come up with the term robustness to account for these consciously designed elements.

Bibliography

Berkes, F., Colding, J., & Folke, C. (2002). Navigating Social-Ecological Systems: Building Resilience for Complexit and Change. Cambridge: Cambridge University Press.

Einhorn, B. (1 Nov, 2016). A water fight like no other maybe brewing on Asia's rivers. Retrieved from Bloomberg: http://www.bloomberg.com/news/features/2016-11-01/a-waterfight-like-no-other-may-be-brewing-over-asia-s-rivers

Holling, C. S. (1973). Resilience and Stability of Ecological Systems. Annual Review of Ecology and Systematics, 1-23.

Overland, M. A. (31 August, 2013). The Salmon Cannon, easier than shooting fish out of a barrel. Retrieved from NPR: http://www.npr.org/sections/thesalt/2014/08/29/344360634/the-salmon-cannon-easier-than-shooting-fish-out-of-a-barrel