A decline spiral is the destruction of a species, ecosystem, or biosphere in a continuing downward trend, leading to ecosystem disruption and impoverishment. The term is sometimes used to describe the loss of biodiversity, when a catastrophic event has led to a sharp decline in the number of organisms in a biological community.

In areas where the habitat is highly fragmented either due to human intervention or natural disaster, the loss of species is markedly accelerated. Loss of species diversity often initiates a downward spiral, as the weakening of even one plant or animal in an ecosystem, especially a keystone species, can lead to the malfunctioning of the biological community as a whole.

Biodiversity exists at several levels within the same community; it can include ecosystem diversity, species diversity, and genetic diversity. Ecosystem diversity refers to the different types of landscapes that are home to living...