It's been 10 years now since the definition of Sustainable YIELD given by Ernest Callenbach first appeared in his “pocket-guide” called Ecology. The definition is provided below so that the reader of the SUSTAINABILITY definition will have the context of the meaning of Sustainable YIELD. Please read the definition of YIELDS below.
The concept of sustainable yield first arose in fisheries and forestry. Sustainable yield measures how many fish, trees, or animals we can "harvest" yearly without reducing the average number fish, the total standing crop of timber, or the POPULATIONS of animal SPECIES, and without reducing the underlying primary productivity that supports them.
Humans, as predators, can consume of a wild species' productivity sustainably because nature provides every species with a surplus of offspring. The young of fish, trees, or any other species suffer heavy reduction by disease and predators before they in turn can reproduce. A hundred mice will produce thousands of offspring, ... [to be compiled completely at a later time].
Robert "Roy" van de Hoek
Sustainable YIELD is a complex term to comprehend in ECOLOGY, and yet is also simple and so quite beautiful in both its complexity and simplicity. The very good definition by Ernest Callenbach helps to further understand Sustainability and Ecology. It entices the reader, at least it does for me, to read further to understand how nature, ecology, and our great planet Earth is wonderful geography of hope.