Qualitative modelling tools for rural ecosystem management

SUMMARY

Shallow lakes and wetlands are highly complex systems in which actions affecting a single compartment can have repercussions far away from the target parameter and those directly related species. In a large-scale study of the Esteros del Ibera wetland in Argentina, researchers have constructed a set of qualitative models with the objective of further understanding the interrelations between management actions and impacts on key abiotic and biotic ecosystem variables. The two qualitative models that have been developed relate to past and future modification of the wetland biotic and abiotic characteristics. The first model examines possible secondary effects of the recently successful ban on caiman hunting. The second model studies the potential impacts of growing regional economic development on water quality and biodiversity of the wetland. The results are qualitative, indicating where further analysis and modelling would be best concentrated.

The output of the two models shows that particular populations (piscivorous waterfowl) and compartments (littoral aquatic macrophytes) are more likely to be sensitive to potential modifications in the ecosystem. This is the result of a number of feedback mechanisms that transfer the effects of management and resource-use practices to these compartments. Based on such observations, more attention has been given to creating monitoring instruments for these variables.

Key words:

• Loop analysis
• qualitative models
• ecosystem management
• wetlands
• piranha
• caiman
• Esteros del Ibera