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News Article

Conserving intact forest landscapes

New analysis argues for intact areas of forest to be given higher priority for conservation

A new global analysis of habitat loss in forests and subsequent wildlife extinction risk has found that species that are most vulnerable, live in areas that are only just beginning to see the impacts of human activities such as ranching, mining, logging and hunting.  The research team argue that areas of forest that are intact deserve higher priority for conservation than those that have already been impacted heavily by human activity, even though species are also at high risk in areas that have already been impacted.

“We have seen declines in species in landscapes that have already lost a massive amount of habitat,” said lead author Professor Matthew Betts of the College of Forestry at Oregon State University.  “ But we found much more support for what we call the initial intrusion hypothesis. It’s the initial hit caused by roads going into tropical forests and the human activities that follow that is most substantial.  These are also the spots with the greatest sheer numbers of species.”

Betts and his team from Oregon State and Birdlife International analysed global datasets of forest habitat and species extinction risk.  The forest data was assembled by Matthew Hansen at the University of Maryland and the extinction risk categories for 19,432 vertebrate species, known as the Red List, is maintained by the International Union of the Conservation of Nature.

The data indicated that forest loss is continuing to occur at high rates, approximately 1.5 million square kilometres, or 371 million acres, per year.  Most of the this loss occurs in the tropics.  South American rainforests account for nearly half of global forest loss.  The analysis shows that in total, 37 percent of the worlds forests have been removed and the land converted for other purposes.

"It should be quite obvious that forest loss increases the risk of species being listed," said Betts. "But our work provides the first global quantitative link between forest loss and forest species decline."

However, the researchers sought to answer the following question: Should conservation efforts be focussed on areas where forests habitats have already been lost and species might be reaching a threshold, or on forests that are largely intact and are only just beginning to be affected by development?

Betts started the Oregon Forest Biodiversity Research Network in order to use large datasets to answer such questions.  In Costa Rica and elsewhere, Betts has studied the impact on forest clearing on hummingbird pollinators as well as other bird species.

It is possible that heavily impacted areas have already gone through what researchers call an “extinction filter” meaning that species that are sensitive to development could have previously been eliminated.  Southeast Asia, Borneo, the central-western Amazon and Congo basin in Africa are high risk hotspots for biodiversity, according to the researchers.  Population growth, bushmeat hunting and resource extraction in response to consumer demand may fuel future extinction risks in these areas.

The debate on whether conservation programs should prioritise forests that area already affected by development is ongoing between policymakers and scientists.  "Granted that there's no such thing as a place that hasn't been touched by humans in some way due, for example, to a changing climate," said Betts. "But then there's the view that humans can quite tightly co-exist with nature assuming that we undertake certain ameliorative measures, that as long as we're softer on Earth, we can still have productive landscapes for agriculture. Our paper suggests that we would be helped by having these intact forest landscapes well protected."

Study co-author Taal Levi said that dedicating some areas to intensive production could enable other areas to be preserved as habitat.  "There are many potential benefits to concentrating our environmental impact by intensifying drivers of land-use change, such as agriculture and forestry, in exchange for gazetting large remote undisturbed reserves. A disproportionately large impact arises from the first disturbance to forests."

Journal Reference

Matthew G. Betts, Christopher Wolf, William J. Ripple, Ben Phalan, Kimberley A. Millers, Adam Duarte, Stuart H. M. Butchart, Taal Levi. Global forest loss disproportionately erodes biodiversity in intact landscapesNature, 2017; DOI: 10.1038/nature23285

Article details

  • Author(s)
  • Stephanie Cole
  • Date
  • 26 July 2017
  • Source
  • Oregon State University
  • Subject(s)
  • Biodiversity