Sustainability has been a key concern in land-management and planning circles for a long time. With ecosystem management, however, focus has shifted from just maintaining "productivity of soil" to "sustaining the integrity of the systems that support life and provide for a quality existence." Zane Cornett and I worked up a definition for sustainability last year:

A Definition of Sustainability for Ecosystem Management
by David C. Iverson and Zane J Cornett

Sustainability is at the heart of many current, and sometimes contentious, discussions relating to all aspects of natural resource management. Part of the struggle has been the search for a definition suitable for an ecosystem management context. A definition is important whether developing a framework or processes for ecosystem management. In defining sustainability, our underlying premise is that ecosystem health is tightly linked to the sustenance of humans, and the quality of their lives.

Our definition of sustainability builds upon a foundation of ecosystem health and integrity, similar to that proposed by Bryan Norton (1992) 1 and recently supported by James Kay (1993)2. Maintaining the health and integrity of ecosystems is necessary, because science is showing us that the consequences of doing otherwise could disrupt ecosystem functions to the point where human existence would no longer be one that we would desire, nor one we would wish to leave to future generations.

We advocate the following definition for the purposes of ecosystem management:

To further clarify this definition of sustainability, we need a complementary definition for integrity. The philosophy of ecosystem management integrates biophysical, cultural, and economic systems into the single concept of "ecosystems".

The definition for integrity is applicable to each of the economic, cultural, and biophysical subsystems, as well as to the integrated ecosystem. When trying to implement this definition, the issue of scale or context is unavoidable. The integrity of biophysical systems, in particular, are dependent upon their context, both spatially (across landscapes) and temporally (multi-generational). Thus, a landscape would have integrity if its ecosystems retain their complexity and capacity for self-organization, and sufficient diversity, within their structures and functions, to maintain the systems' self-organizing complexity through time.

These concepts are fundamentally linked to and driven by the reality of five axioms of ecosystem management proposed by Norton: