Development of State-and-Transition Models (STM): Integrating Ecosystem Function, Structure and Energy to STM

Document Type : Research and Full Length Article


1 Faculty of Rangeland and Watershed Management, Gorgan Agricultural and Natural Resource Sciences University, Gorgan

2 Rangeland Sciences, Faculty of Rangeland and Watershed Management, Gorgan University of Agricultural Sciences & Natural Resources, Gorgan


The main objective of an ecosystem sustainable management is to preserve its
capacity to respond and adapt to current disturbances and/or future changes, and maintain the
provision of environmental goods and services. Two very important properties linked to this
objective are the ecosystem resilience and resistance to disturbance factors. The objective of
this paper is to recommend conceptual modifications to the integration of key ecological
concepts such as dynamic equilibrium, resistance and resilience to the ‘State and Transition
Model’ (STM) in order to apply them in a more feasible way for rangeland management.
Ecological resilience describes the amount of change or disruption required to transform a
system from being maintained by one set of mutually reinforcing processes and structures to a
different set of processes and structures. STMs integrated to concepts of structure, function
and energy provides greater opportunities to incorporate adaptive management, more accurate
forecasts and a better and easier comparison between rangeland ecosystem types than
traditional STMs. We propose to enhance the STM considering four principal axes (ecosystem
functions and/or processes, natural disturbances and/or negative management activities,
required energy to return to the previous state, and structural ecosystem changes and transition
time) also simultaneously, to compare the “robust” ecosystem to “fragile” ecosystem. The
recommended modifications enable STMs to identify a broader range of variables to anticipate
and identify conditions which determine state resilience to better inform ecosystem managers
of risk and restoration options.