2.1 Alternate States

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Managing resilience requires understanding the potential alternate states in your system and the processes involved in changing from one state to another.

Example: Shrubs v.s. Grasses on SavannasSome systems can exhibit a lot of variation over days, months, years etc. but alternate states are distinguished by a different structure or composition of organisms and a change in the processes that reinforce a particular state. One can draw on past experiences and future projections to consider possible alternate system states. When looking at the processes underlying a change of state, it is important to pay attention to social, economic, and ecological domains.

Key Messages

• Many systems show consistent traits over long periods of time. Grasses and sparse trees characterize savanna ecosystems. Coral reefs are characterized by diverse coral colonies and communities of fish.

• The existence of these long-term and persistent characteristics led scientists to recognize a phenomenon known as stable states. ‘Stable’ in this sense doesn’t imply unchanging. There is usually some level of variation while the overall characteristics of the system remain largely the same. The assemblage of fish species in a freshwater system may change with time but the system remains more or less the same. Similarly, politicians can come and go, while the form of government remains unchanged.

• Some systems may have only one stable state. A disturbance might temporarily move the system away from the stable state, but once the disturbance passes, the system will return to its normal state. For example, if a grassy savanna had only the stable state of being grass-dominated, cattle grazing might reduce the grass biomass, but once cattle were removed, the grass would recover its original levels.

• For many complex systems there are likely to be two or more alternate states. Savannas can be mostly grassy or mostly woody; coral reefs can be dominated by corals and fishes or be covered in algae; lakes may be clear or cloudy with algal blooms.

• Some system states are difficult, bordering on impossible to change. These are highly resilient states, though they may not necessarily be desirable states.

• The challenge is to make desirable states more resilient, undesirable states less resilient, and to recognize that thresholds separate alternate states.

Resilience Assessment

In the assessment that follows you will attempt to define potential alternate states for your system and the processes that might move your system from one state to another. Drawing on both historical events and future projections, you will explore the potential for alternate states in your focal system. It is not necessary at this stage, nor may it be possible, to know the exact position of thresholds between states.

Suggest and define possible or probable alternate states for your focal system. Considering the history of the system may help in identifying likely alternate states. It might also be helpful to think about the range of conditions seen in other similar systems. Another approach might be to consider different trajectories and future scenarios for the system (see chapter 5 for more on scenarios). Past management assessments and modeling efforts may also have identified or suggested alternate system states. These states may be primarily in the ecological realm and/or the social realm.

Briefly summarize the ecological, economic, and social characteristics of each possible alternate state.

Attempt to define the desirability of each of the states listed above based on the norms and values of different stakeholders. Indicate whether participants agree on desirability of states. If there is no agreement, what are the sources of these differences? How would you go about resolving these differences?

Often it is useful to graphically depict system states and the processes that influence the transitions among states. Two such examples are given below. The first is a state-and-transition model for a semi-arid rangeland system. The boxes define four alternate states (including a transitory state labeled II in the diagram) and the arrows indicate transitions (T) among the states.


Image:StateTransition.gif

Figure 2.1.3 State and transition diagram for a savanna system.


Draw a diagram of the type in Figure 2.1.3 for your focal system, depicting alternate states as boxes. Label each box and possible transitions among the boxes. For each transition, describe the ecological, social, or economic process that influences the transition. For instance, in the savanna example used earlier, we consider how grazing could move a savanna system from a grassy to a woody state. Note that there may be more than one arrow between states, and some processes may appear more than once (e.g. grazing may be important both in moving the system from state A to state B, and from state B to state C). A more thorough consideration of factors or events that might trigger changes in state will be covered in the next section.

A second example of a state and transition model, this time for a sylvo-pastoral system is shown in Figure 2.1.4. This model below was used in a role-playing game to help managers decide on appropriate actions. It identifies different states of the system that have different consequences for people, and the natural and human drivers of the transitions between states.

Image:SylvoPastoral.gif

Figure 2.1.4 A State-and-Transition model for a sylvo-pastoral system (from Etienne 2003, Figure 5).

Models of alternate states and the pathways between them can be valuable tools for managing for resilience. Developing a conceptual model also brings to the forefront an individual’s or group’s existing mental model(s) and can facilitate a process of synthesizing diverse perspectives. Have there been past efforts to model alternate states of your focal system and the processes that would move your focal system from one state to the next? If not, or if these efforts have been inadequate or incomplete, identify local scientists and/or modelers (from both the ecological and social sciences) who might help in devising future dynamic models of alternate states. Develop a plan for engaging them either in this process or in subsequent processes. Make a record of any action items.



2.1 Alternate States

2.2 Thresholds

2.3 Scenarios

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