<P> Although, there is no single cause for ecological collapse, attributing factors include asteroid impacts, extremely large volcanic eruptions, and abrupt climate change . The snowball effect of these attributing factors and ecological collapse are demonstrated within the fossil record . Prehistoric examples include the Carboniferous Rainforest Collapse, the Cretaceous--Paleogene extinction event, the Permian--Triassic extinction event, and other mass extinctions . For example, effects of climate change as a contributing factor towards ecological collapse are demonstrated in the Ordovician--Silurian extinction events . A possible cause of the Ordovician Extinction was global cooling which affected the habitats of marine life . Consequently, sea creatures such as trilobites, brachiopods, and graptolites became extinct . Furthermore, Karabonov and colleagues conducted a study to show how during the Last Glacial Maximum (LGM), alternations in the environment and climate led to ecological collapse in Lake Baikal and Lake Hovsgol which then led to species evolution in these systems . The collapse of Hovsgol's ecosystem during the LGM brought forth a new ecosystem, with limited biodiversity in species and low levels of endemism, in Hovsgol during the Holocene . Karabonov's study also shows that ecological collapse during LGM in Lake Hovsgol led to higher levels of diversity and higher levels of endemism as a byproduct of evolution following the ecological collapse of the LGM . The Ordovician Extinction event and Lake Baikal and Hovsgol demonstrate two effects of ecological collapse on prehistoric environments . </P> <P> Historic examples include the collapse of the Grand Banks cod in the early 1990s, attributed to overfishing . </P> <P> Important pressures contributing to current and future ecological collapse include habitat loss, degradation, and fragmentation, overgrazing, overexploitation of ecosystems by humans, human industrial growth and overpopulation, climate change, ocean acidification, pollution, and invasive species . </P> <P> Rainforest collapse refers to the actual past and theoretical future ecological collapse of rainforests . It may involve habitat fragmentation to the point where little rainforest biome is left, and rainforest species only survive in isolated refugia . Habitat fragmentation can be caused by roads . When humans start to cut down the trees for logging, secondary roads are created that will go unused after its primary use . Once abandoned, the plants of the rainforest will find it difficult to grow back in that area . Forest fragmentation also opens the path for illegal hunting . Species have a hard time finding a new place to settle in these fragments causing ecological collapse . This leads to extinction of many animals in the rainforest . </P>

Example of a major disturbance that caused the ecosystem to completely collapse