Components, energy flow, and matter cycling.

1. an ecosystem is an abstract concept, biological and physical.

2. It stands for a dialectical analysis of natural areas by looking at two distinct, yet related parts: the organic and inorganic conditions of existence.

3. But the concept emphasizes materials and how they are transformed fom the nonliving to the living and back through the nonliving parts of the natural area.

4. The materials are moved through natural systems and compounds are transformed by the degradation of energy from one form into another.

The environment's systemic qualities sustain human societies.


The complexity of ecosystems can be summed up several ways.


One key way is by reference to the conversion of solar and thermal energy that moves trace elements and nutrients through ever more diverse assemblages of life so that they may continue to eat the storms–enfolding them into their genes in order to hold the world steady; for that is the process which created us and for which we must labor, with due care, if we are all to survive with dignity.

Conditions of material existence

inorganic organic
non-living living
habitat biotic community
energy food webs


Components of an ecosystem diagramed Nitrogen cycle of nutrient moving through the ecosystem

Nitrogen is an important cycle that moves from the air into the soil, into living creatures and back through the environment and it does so in a manner that perpetuates the ecological system.

ecological facets of energy flow

Miller emphasizes "system's analysis," and "ecosystem services."

Wilson's Storm
Myer's Giant Forest Powerhouse
Leopold's Wolfless Mountains
Dillard's Weasels, predation & freedom
• Colinvaux's niche as Miller's "place to live?"

G. Tyler Miller, Chapter 4