Limiting Factors

Recall from Chapter 3 that the primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient. Ecologists call such substances limiting nutrients. A limiting nutrient is an example of a more general ecological concept: a limiting factor. In the context of populations, a limiting factor is a factor that causes population growth to decrease. Some of the limiting factors that can affect a population are shown in the figure at right.

Limiting Factors

A resource base that is limited can also affect the long-term survival of a species. For example, pandas depend for food on bamboo that grows in certain kinds of temperate forests in China. Since the time that these forests have been cleared for timber and farmland, panda populations have fallen dramatically and have become isolated in small pockets of remaining forest.