Ecosystem decay

Ecosystem Decay is a term coined by Thomas Lovejoy to define the process of which species become extinct locally based on habitat fragmentation.^[1] The process is ultimately what caused several species to go extinct, including the Irish Elk. The most dominant factor in this process is isolation and thus, inbreeding of animals which will lead to the local population's demise as small areas cannot support enough genes for inbreeding to not occur.

Ecosystem decay is caused by multiple factors, one of which is inbreeding. Another factor is the absence of rivals and neighbors from which they might learn. The resident populations will have had to adjust their diet and other fundamental factors in order to survive.

This principle is very similar to Forest fragmentation except for the fact that ecosystem decay is what results in the event of forest fragmentation. This may also follow the principles of Island Biogeography somewhat.

Overview

Ecosystem decay is a natural phenomenon that has several resulting features.^[2]

• Decline of native populations of animals
• Decrease in genetic diversity
• Decrease of the interior:edge ratio
• Isolation of an area of viable habitat
• Reduction in viable habitats and often extreme separation

Process

The process through which ecosystem decay occurs can be long and complicated or short and hasty. Overall, it still follows some basic guidelines. First, a piece of habitat is surrounded and thus isolated by farmland or cities. Secondly, pollination of the plants immediately ceases and the number of species thins out. Thirdly, through generations of inbreeding and thus higher birth mortality than birth survival rate and infertile dirt, the forest fragment will slowly decline to nothing.

Causes

Ecosystem decay is commonly caused by the harvesting of rain forest in appliance to certain laws or illegally for profit by humans. Certain countries such as Brazil prohibit the harvesting of Brazil nut trees and groves of this species causing forest fragmentation and thus causing ecosystem decay to occur. Cities, roads, farms and any other substantial barrier impeding and animals habitat can be a direct or an indirect cause. Naturally, fires and rising sea levels on low land can also cause habitat fragmentation and thus ecosystem decay. Although this process is much more lengthy, many species such as the Irish Elk and several species of ancient Australian Marsupials have been indirectly killed this way with contributions by Climate Change, Glaciation and Forest Fires.

Studies

Eleonore Setz^[3] was studying a patch of equatorial rainforest named reserve #1202 containing Pithecia pithecia (white-faced sakis), to study the effects of ecosystem decay. The 9.2 hectare (less than 25 acre) area had been isolated for five years when David Quammen noted results on the fragmentation of their habitat which resulted in them being stranded. The population of P. Pithecia was slowly declining at the time of the study and the population had declined to six.

References

General References

^{[1] [2] [3]}

1. ↑ Harris, Larry D. (1984). The Fragmented Forest: Island Biogeography Theory and the Preservation of Biotic Diversity. The University of Chicago Press. ISBN 0-226-31763-3.
2. ↑ Ecosystem Decay of Amazonian Forest Fragments: a 22-Year Investigation (Conservation Biology, Pages 605–618 Volume 16, No. 3, June 2002) William F. Laurance, Thomas E. Lovejoy, Heraldo L. Vasconcelos, Emilio M. Bruna, Raphael K. Didham, Philip C. Stouffer, Claude Gascon, Richard O. Bierregaard, Susan Laurance and Erica Sampaio
3. ↑ "Decay of Interspecific Avian Flock Networks along a Disturbance Gradient in Amazonia." Decay of Interspecific Avian Flock Networks along a Disturbance Gradient in Amazonia. N.p., n.d. Web. 12 Nov. 2015.