Old-growth forests are irreplaceable for sustaining biodiversity

Rhett Butler in Mongabay: Old growth rainforests should be a top conservation priority when it comes to protecting wildlife, reports a new comprehensive assessment published in the journal Nature. The research, which was led by Luke Gibson of the National University of Singapore and Tien Ming Lee of the University of California at San Diego and involved scientists from a range of international institutions, examined 138 scientific studies across 28 tropical countries. It found consistently that biodiversity level were substantially lower in disturbed forests.

"There's no substitute for primary forests," said Gibson in a statement. "All major forms of disturbance invariably reduce biodiversity in tropical forests."

The research found that certain groups are more affected by forest degradation than others. Mammals seem to adapt more readily than birds and insects. The study did not assess the impact of degradation on freshwater fish, reptiles, or amphibians — groups known to be particularly sensitive to ecological change.

The findings are important because primary forests continue to fall at a rapid rate. According to the FAO, old growth forest cover declined by a minimum of 42 million hectares (162,000 square miles) — an area nearly the size of California — during the 2000s. Much of the loss was the result of selective logging, which while less damaging to biodiversity than outright conversion for agriculture, increases the vulnerability of forests to fire and future deforestation. Logging roads cut into remote forest areas typically grant access to developers, small farmers, and hunters...

Henri Rousseau, "In a Tropical Forest. Struggle between Tiger and Bull," circa 1908 or 1909