What is green world hypothesis?

Question

What is green world hypothesis?

Answer 1

The green world hypothesis states that terrestrial herbivores consume relatively little plant biomass because they are held in check by a variety of factors, including predators, parasites, and disease.

Several factors that the green world hypothesis suggests keep herbivores in check are:

Plants have defenses against herbivores such as noxious chemicals and spines.

Nutrients, not energy supply, usually limit herbivores. Plants give off a low supply of protein, which animals need.

Abiotic factors also limit herbivores. Changes in temperature and moisture will lower the carrying capacity of herbivores so that they're unable to strip an area of its vegetation.

Intraspecific competition limits herbivore numbers because they may battle over territory or mates.

Interspecific interactions such as predation and disease will kill herbivore densities in check. This is said to be the most important limiting factor.

Because of all these, herbivores consume only about 17% of net primary production by plants.

Of course, there are always exceptions. Like the gypsy moth in the northeastern United States.

Answer 2

Predators are, ironically, the key to keeping the world green, because they keep the numbers of plant-eating herbivores under control.

The "green world hypothesis" was first proposed in 1960 by United States scientists Nelson Hairston, Frederick Smith and Lawrence Slobodkin.

http://www.sciencedaily.com/releases/200...