Death rate

The rate at which a population is losing individuals. When the death rate is constant, and equal to the birth rate, the population size does not change. When the death rate exceeds the birth rate, the population growth is negative, and the population size declines. But when the birth rate exceeds the death rate, the population growth is positive, and the population size increases. When the positive population growth is very rapid, and it is called a population explosion. This rapid rate is typical of r-strategists. deBary

The German botanist Heinrich Anton deBary (1831-88) is considered the founder of modern mycology. Deccan hemp

See: Hibiscus cannabis. Deciduous

The habit of some trees and shrubs of shedding their leaves, by abscission, at the end of each growing season. The function of this habit is usually to escape an adverse season, such as a winter, or a tropical dry season. However, the deciduous habit also has advantages in the control of leaf parasites by providing a discontinuous pathosystem in which a gene-for-gene relationship can operate as a system of biochemical locking. Most deciduous trees are Angiosperms. See also: n/2 model Seasonal tissue.

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