Humans may be the best "space invaders" on the planet. We cut down forests, build roadways, produce crops, and mine for minerals. These activities result in habitat loss for plants, animals, and other organisms and also pose a threat to biodiversity.
"By acting quickly, we can dramatically reduce loss of species in habitat remnants." -William Newmark, Conservation Biologist
William Newmark, a conservation biologist and research curator at the Natural History Museum of Utah said habitat loss is the largest cause of species disappearance worldwide and believes using theoretical approaches to estimate the timeframe of extinction may help save species. Newmark and his colleagues set out to predict how quickly extinction occurs as a result of habitat fragmentation. They recently published their findings in the journal Nature Communications.
"In most cases, the habitat is not completely eliminated, but instead reduced from a large to small area. Because of this, there is a lag period between when habitat is lost and when species disappear," he said. "There is an extinction debt. These are species that are doomed to extinction, but have not yet disappeared. The question is how quickly will this happen when we create a fragment. When will we lose the first species and when will we lose half of the species?"
The research team developed a model for examining extinction rates, made predictions based on the model, and compared those predictions to what has been observed in nature.
"We found a very close fit between the model results and the observed patterns of species extinction in habitat remnants. This gave us confidence that the model was valid. No model is perfect, but it will allow us to predict," Newmark said.
Initially, extinction occurs quickly, but then slows as more species disappear. When 50% of all species are lost, half of the extinction debt is paid. Extinction continues, albeit at a slow rate, as the remaining debt is paid off and eventually a balance is reached between the size of the fragment and the number of species it can hold.
"By acting quickly, we can dramatically reduce loss of species in habitat remnants through restoration," said Newmark.
This may include creation of corridors or "animal roadways," which provide additional habitat and allow species to move from one place to another. Corridors can be especially useful when a man-made structure, such as a road, separates habitats. Other considerations, such as understanding animal behavior can also make a difference. Many birds nest in old growth trees. Knowledge, such as this, may influence a deforestation plan.
The species extinction model has significant implications for conservation. If accurate predictions on rates of extinction are made, action can be taken before it’s too late.
Additional Information: This work was a collaboration between the University of Ioannina, Aristotle University of Thessaloniki, and the Natural History Museum of Utah.
Journal reference: John M. Halley, Nikolaos Monokrousos, Antonios D. Mazaris, William D. Newmark, Despoina Vokou. Dynamics of extinction debt across five taxonomic groups. Nature Communications, 2016; 7: 12283 DOI: 10.1038/ncomms12283
