Small-scale farmers often plant several different food crops so that failure of any one crop will not have catastrophic impacts on food provision. Similarly, natural resource harvesting systems, which target a number of different species, are more resilient than systems which target single species. Evidence from several other fields of study suggests that systems with many different components are generally more resilient than systems with few components. Functional redundancy, or the presence of multiple components that can perform the same function, can provide ‘insurance’ within a system by allowing some components to compensate for the loss or failure of others. In short, redundancy is embodied in the saying “don’t put all your eggs in one basket”.
Redundancy is even more valuable if the components providing it also react differently to change and disturbance. This is what we call response diversity (differences in the size or scale of the components performing a particular function give them different strengths and weaknesses, so that a particular disturbance is unlikely to present the same risk to all components at once). For example, seed dispersal in Ugandan forests is performed by a range of different-sized mammals, from mice to chimpanzees. While the small mammals are negatively affected by local disturbances, the larger, more mobile species are not and can therefore maintain their function as seed dispersers.
Within a governance system, a variety of organisational forms such as government departments, NGOs and community groups can overlap in function and provide a diversity of responses, because organisations with different sizes, cultures, funding mechanisms and internal structures are likely to respond differently to economic and political changes. Diverse groups of actors with different roles are critical in the resilience of social-ecological systems, as they provide overlapping functions with different strengths. In a well-connected community, where functions overlap and redundancy is present, creativity and adapt-ability can flourish.
A diversity of users and managers can also safeguard the sustainable use of a resource. For example, within fishing communities, people of different ages, genders and financial means may favour different fishing methods and types of gear. This diversity enhances the ability of the whole community to detect and understand ecological changes because each user has a perspective on a different part of the system. Investment in diversity and redundancy can enhance the resilience of people’s livelihoods because it enables people to adjust in response to changes in the market or the environment. For example, a substantial number of farmers in the drier parts of South Africa and Namibia have shifted from cattle ranching to wildlife ecotourism in response to a growing market preference for cultural ecosystem services. Farmers are more easily able to make this switch if the natural biodiversity on their farms is relatively intact.
How can we maintain diversity and redundancy?
Management can and should recognize and incorporate the value of diversity and redundancy in the management of social-ecological systems in order to build resilience. This can be achieved by paying attention to the following aspects:
Conserve and value redundancy. Redundancy is seldom explicitly conserved or managed, but is just as important as diversity in providing resilience. Particular focus should be paid to important functions or services with low redundancy, such as those controlled by key species or actors. In some cases it may be possible to increase the redundancy associated with these functions.
Maintain ecological diversity. Biodiversity is essential for ecosystem services such as pollination, pest control, nutrient cycling and waste assimilation. In addition, natural biodiversity can improve the resilience of these services by providing a reservoir of redundancy and response diversity and by reducing the dependence of agricultural systems on external inputs of fodder, fertilizers and pesticides. Strategies for maintaining or enhancing ecological diversity include maintaining structural complexity in landscapes, establishing buffers around sensitive areas, creating corridors for connectivity and controlling overabundant invasive species. In an urban context, ‘green infrastructure’ in the form of vegetated open space networks can be a more resilient way of providing ecosystem services such as storm water management, compared to ‘grey infrastructure’ such as concrete pipes.
Build diversity and redundancy into governance systems. Organisations need to recognise and better incorporate the value of diverse sources of knowledge. Provided this is balanced against costs and the risk of conflicting agendas, a diversity of perspectives can improve problem solving and support both learning and innovation. This can allow for quicker recovery after a disturbance.
Focus less on maximum efficiency, even if it costs more. Conventional economic thinking promotes maximum efficiency, while resilience thinking encourages policies that can better cope with ecological, market or conflict-related shocks. Alternative development programmes can be guided by principles of disparity and response diversity. For example, in farming communities livelihood options that are dissimilar to farming, such as a tourism-related activities rather than alternative types of farming, will provide greater response diversity and thus resilience to shocks. Specific incentives can be created to encourage such diversification at the individual farmer level.