Table 1. Important ecological components of any ecosystem definition (Vogt et al. 1997:71-72)

1. Integration of all biological (biotic) and nonbiological (abiotic) parts
2. Monitoring the movement of energy and materials (including water, chemicals, nutrients, pollutants, etc.) into and out of its boundaries
3. Utilization of a common currency called energy to measure ecosystem function and the strength of the links between different ecosystem components. In practice, changes in organic matter or carbon accumulation (i.e., net primary production) over a defined space and over a given time period is used as a surrogate for energy because photosynthesis, which fixes carbon, is an energy-assimilating process
4. Boundary definitions—a site that can be bounded by identifying the smallest unit that is self-sustaining
5. Explicit incorporation of spatial and temporal scales
6. Encompassing system or species characteristics that are highly interdependent and have strong feedback loops. Feedback loops can be expressed at the species or ecosystem level (i.e., keystone or functional groups) and can be driven by microbes and/or consumers
7. Incorporating disturbance cycles at defined temporal and spatial scales, explicitly acknowledging that disturbances can occur at varying scales and are an integral part of ecosystems. Identifies the importance of legacies (imprint of past disturbances or structures) and how they have contributed to the development of the current ecosystem structure and function
8. Characterization of all of the above for the multiple states that a system can fluctuate between as part of the natural development of that system