3. Resilience of social-ecological systems (SESs)

Integration of ecology and sociology:
Social-ecological systems

The network of resilience researchers formed an organization called the Resilience Alliance (RA). It was founded in 1999, and Professor Walker became its first Director.

With RA members in Corsica, Italy

With RA members in Corsica, Italy
Professor Walker is in the front row third from left. (2007)

The purpose of the RA is to understand resilience without limiting the ecological systems being studied. Professor Walker became interested in human society as an ecosystem. He thought resilience, the ability to respond to change, was essential for maintaining human society too.
In cooperation with many sociologists who participated in the RA, Professor Walker sought to understand the complexity and functions of society and what humankind needed to do to increase its resilience.
Professor Walker came to think that it would be better to consider ecosystems and human society together.

The Murray-Darling basin, the largest agricultural area in Australia, is an example of this. Irrigated agriculture is actively practiced in the area. From the ecological perspective, this basin has rivers and plants on arable land. From the perspective of society, the basin has farm houses in settlements where a wide range of people live. The system of irrigated agriculture is formed by both the ecosystem and human society in this area.
An integrated system such as is seen in the Murray-Darling basin involves an ecosystem and human society in an interdependent relationship. This is called a social-ecological system (SES).

At one point in time, water in the Murray-Darling basin decreased. The lack of water meant that irrigated agriculture could not continue.
It was proposed that irrigated agriculture be stopped in part of the basin, and replaced by dryland agriculture, farming that does not require water. The ecosystem and human society would change significantly there; however, people would be able to continue farming. In addition, the reduced water flowing into the area of dryland agriculture could be diverted for use in irrigated agriculture in other areas. To continue as an agricultural area, the basin needed to change its system.

Irrigated agriculture

As was seen above, maintaining a social-ecological system does not mean to maintain a completely original state. A flexible response to change is sometimes necessary to maintain the important functions of a system.
Our understanding of the interactions between ecosystems and human society allows us to prevent the systems from deteriorating and lead to an increase in the resilience of social-ecological systems.

A definition of resilience

Professor Walker defined resilience simply as the ability of a system in nature to maintain its original state.
Resilience is the capacity of a system to create a balance to maintain its functions before changing into something different or being destroyed.
Professor Walker points out that it is our mission to establish a system that can respond to any kind of change and continue to restore itself as much as possible, which means establishing a system with high resilience.

Professor Walker identified three elements required to establish a system with high resilience. The first is to understand the threshold of the social-ecological system. The second one is adaptive capacity, or in other words, how to deal with the threshold. The third is transformation. For example, people needed to accept the idea of changing their existing method of agriculture to maintain the Murry-Darling basin as farmland. In other words, we need to create a fundamentally new system when current conditions make the existing system untenable.

What is a world with high resilience?

What creates high resilience specifically? The important factor for resilience in ecosystems is diversity. For example, many leguminous plants store the nitrogen that maintains soil fertility. If there is only one species of leguminous plants growing in an area and it completely perishes due to bacteria or drought, the function of nitrogen storage is lost. However, if there is a wide variety of leguminous plants and some species have strong resistance against bacteria and drought, the nitrogen storage function will be maintained. The diversity of response to environmental change among species contributing to the same ecosystem function is called response diversity. Response diversity is extremely important in maintaining a high capacity for restoration. In other words, response diversity is essential to ensuring a system with high resilience.

Such diversity is sometimes neglected in today's world. "Why do we need to have many kinds of plants that store nitrogen? It's enough to have one kind that is highly effective." Cultivating one crop or planting one kind of tree based on such thinking will lead to the loss of resilience in the farmland or the forest.
The same thing happens around us as well. We tend to think that simplifying the structures and relationships in society is the best way to increase their efficiency.

Professor Walker is concerned about this. He thinks it is necessary to have a wide range of ways to maintain high resilience in the systems we have developed. If there are many ways, it does not matter if one of them fails for one reason or another. However, if there is only one way and it fails, the system will be destroyed.

Training for rice growing in Indonesia (2000)

Training for rice growing in Indonesia (2000)

He insists that maintaining or establishing response diversity is one of the most essential conditions for increasing the resilience of ecosystems.

4. Wishes for the future

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Prof. Brian Walker

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