Permaculture Designers Manual


Section 2.13 –

Time and Yield in Permaculture

Old systems store up their energy in bulky unproductive forms, e.g. an old forest has large trunks, roots and limbs, and old fish are “on maintenance“.

Such ancient systems composed of large individuals (trees or animals) need energy just to maintain their health, and thus they can use less of the available sun energy, so that flow of energy through the system is less.

Therefore the yield, or turnover of matter, is less. This too is a function of time (ageing). Matter is used up in system maintenance, and is not available as yield, or as increasing size or weight in life components.

Against this factor, species diversity (richness) works to make the most of incoming energy.


Carlander has shown that the standing crop of fish in different reservoirs is an increasing function of the number of species present. (Watt)

This is also true of studies in most “wild” systems, where the complexity and standing crop are both much more than the simple cultivated ecology which replaces them.

Thus, the dearing of an African veld or an Australian savannah of their web of species, and their replacement with a few perennial pasture plants and beef cattle, or with a single-species pine forest not only takes enormous energy but also grossly decreases total yields.

We would do better to try to understand how to manage natural yields, and modify such systems by management than to replace them with “economic” (here economic means monetary rather than energy return) systems which impoverish the yield and encourage disaster via pests and soil loss.

Economics in future will inevitably be tied to yield judged on energy rather than on  monetary return. In the present economy, we waste energy to make money. But in the very near future, any system which wastes energy must fail.


Pond and hedgerows both slowly gain species as they age, probably as a function of natural dispersal plus new niche evolution created by other species.

This continues until the system begins to be overshadowed by a few large dominants or hyper-predators whose biomass represents an end storage of energy, and a decreasing yield in the total system.

Only local disturbance (fire, wood, death) renews the now of energy through old systems. The time of cycling of natural systems may be a very long period, but in annual cropping it may be reduced to just one season or less.


Permaculture thus uses the time resource much better than does annual  gardening alone, and so uses sun energy to better effect.”


The mixed ecology of annuals and perennials maximizes not only product yield, but also the resourcefulness of the men and women who establish, control, and harvest..

It is only in a thoughtless, monetary, and doomed economy that we can evolve the concept of unemployed and unwanted human beings.

Death in over-mature systems is thus seen as the essential renewal of life, not in the negativistic sense of the fatalist, but in a positivistic and natural way.

It is better that elements die, and are renewed by other species, than the system simplifies to extinction.

It is better for the tribe if its components change than if it turns in on itself, ages, and decays as a whole. Life is then seen as a preparation for succession and renewal, rather than a journey to extinction.


Time as Watt notes is a resource. Like all resources, too much of it becomes counterproductive, and a system in which too much time is accumulated becomes chronically polluted, as a system in which not enough time has accumulated is below peak yield.

A strawberry seedling and an old strawberry bush are equally unproductive, as are the very young and the very old in society.

As there are age-specific diseases in people (whooping cough, prostate hypertrophy) so there are age-specific diseases in whole systems, and a mixed-age stand is the best insurance against complete failure or epidemic disease of this nature.

As individuals, we have a right to use a responsible life, and a right to die.

If our effort to prevent ageing succeed, we may produce a crowded, unstable, and unproductive society subject to gerontocratic peevishness!