New Food-chains for Old

Abstract

The natural living world is arranged in very complex channels of supply that are known as food-chains. From the plant through different species of animals there are usually several, often as many as five stages, but seldom more than that. Alfred Lotka called these chains of species connected energy transformers, because each species was using up in maintenance, movement, and increase some of the energy originally captured by plants from sunlight, and passing it on to another in the cycle of supply. ‘The entire body of all these species of organisms, together with certain inorganic structures, constitute one great world-wide transformer. It is well to accustom the mind to think of this as one vast unit, one great empire.’²⁵⁷ Each species degrades the organic energy into heat, or else its body is devoured alive or dead. Even the animals right at the end of the food-chain are devoured when they die. The living plant is usually able to keep the greater part of itself intact while it is alive, although a not inconsiderable fraction of it passes into animal food-chains. But probably much the greater volume is handed on after the plant dies or in the leaves it sheds, and to a lesser extent when the animal dies. Of course, if this were not so, we should not behold the solid mass of green vegetation, the living basis of all communities would be weak, and the life of whole communities very precarious, which certainly is not generally so in natural ones. While they are alive plants and animals may shed part of their bodies (as with leaf litter, pollen, or moulted insect skins), give off secretions (as with nectar and aphid secretions) or excretions (especially impressive with large ruminant animals, though just as important though less obvious in others).