Ecological collapse

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Ecological collapse refers to a situation where an ecosystem suffers a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction. Usually, an ecological collapse is precipitated by a disastrous event occurring on a short time scale.

Ecosystems have the ability to rebound from a disruptive agent. The difference between collapse or a gentle rebound is determined by two factors —- the toxicity of the introduced element and the resiliency of the original ecosystem.[citation needed]

Through natural selection the planet's species have continuously adapted to change through variation in their biological composition and distribution. Mathematically it can be demonstrated that greater numbers of different biological factors tend to dampen fluctuations in each of the individual factors .[citation needed]

Examples[edit]

Prehistoric examples include the Carboniferous Rainforest Collapse, the Cretaceous–Paleogene extinction event, the Permian–Triassic extinction event, and other mass extinctions. These have been attributed to asteroid impacts, extremely large volcanic eruptions, and abrupt climate change.

Historic examples include the collapse of the Grand Banks cod in the early 1990s, attributed to overfishing.

Important pressures contributing to current and future ecological collapse include habitat loss, degradation, and fragmentation, overexploitation of ecosystems by humans, climate change, ocean acidification, pollution, and invasive species.[1]

Rainforest collapse[edit]

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.

Carboniferous period[edit]

In the Carboniferous period, coal forests, great tropical wetlands, extended over much of Euramerica (Europe and America). This land supported towering lycopsids which fragmented and collapsed abruptly.[2] The collapse of the rainforests during the Carboniferous has been attributed to multiple causes, including climate change.[3] Specifically, at this time climate became cooler and drier, conditions that are not favourable to the growth of rainforests and much of the biodiversity within them. This sudden collapse affected several large groups including lycopsids and amphibians. Reptiles prospered in the new environment due to adaptations that let them thrive in drier conditions.[2]

Fishbone pattern of rainforest fragmentation

Today[edit]

A classic pattern of forest fragmentation is occurring in many rainforests including those of the Amazon, specifically a 'fishbone' pattern formed by the development of roads into the forest. This is of great concern, not only because of the loss of a biome with many untapped resources, but also because animal species extinction is known to correlate with habitat fragmentation.[4]

See also[edit]

References[edit]

  1. ^ "Living Planet Report". World Wildlife Fund. 
  2. ^ a b Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology 38 (12): 1079–1082. doi:10.1130/G31182.1. 
  3. ^ Fielding, C.R., Frank, T.D., Birgenheier, L.P., Rygel, M.C., Jones, A.T., and Roberts, J. (20). "Stratigraphic imprint of the Late Palaeozoic Ice Age in eastern Australia: A record of alternating glacial and nonglacial climate regime". Geological Society of London Journal: 129–140. 
  4. ^ Rosenzweig, Michael L. (1995). Species diversity in space and time. Cambridge, United Kingdom: Cambridge University Press.