The Global Extinction crisis may have been Overstated


 

Two researchers say the damage to the world’s tropical forests may not be as bad as first feared. Because population growth is slowing in many countries and people are moving to cities, the pressure to cut down primary rainforest and use marginal land for agriculture is falling, according to Joseph Wright of the Smithsonian Tropical Research Institute in Panama and Helene Muller-Landau of the University of Minnesota.

If current trends continue, the area of tropical of forest will still be at one third of its natural range by by 2030, say the scientists. The area of tropical forest in Latin America and Asia could actually increase. Those predictions mean that in Africa 16-35% of tropical-forest species will become extinct by 2030, in Asia, 21-24% and in Latin America, fewer still, according to the Economist, which first reported the story.

While those numbers may seem high, they are a far cry from figures like the extinction of 100 species per day or one half of all species currently alive today, as other reports have suggested.

The Wright and Muller-Landau depends on the regrowth of secondary forest. Within a few decades of deforestation, half of the original biomass has returned. However, the new growth probably doesn’t mean that half of the species have returned. The first colonizers to barren land are insects and small animals. Larger mammals are more vulnerable to changes to their habitat, and may take longer to return, says Nigel Stork at the University of Melbourne. For example, “empty forest syndrome” is used to describe forested areas that look healthy from satellite images, but have lost their larger animals through hunting or other population pressures. Another criticism is whether slowing population growth will help as much as claimed. Some scientists, like William Laurance, also at the Smithsonian Tropical Research Institute, say economic growth may be more important. Activities like road building, plantations, soy-bean farming and oil and gas development can all lead to deforestation, even when human population growth has slowed.


 

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