By IANS,
Washington : Common tree species will survive deforestation and road-building, but half of the rare trees in the Amazon could become extinct, Smithsonian scientists have warned.
How resilient will natural systems be as they tide over decades of severe, human-induced global change? The debate is on between proponents of models that maximise and minimise extinction rates.
The Amazon basin makes up 40 percent of the existing global rainforest. A fundamental characteristic of tropical forests is the presence of very rare tree species. Competing models of relative species yield different proportions of rare trees in the forest.
Thirty years ago Stephen P. Hubbell, senior scientist of Smithsonian Tropical Research Institute (STRI) and his colleague Robin Foster, now at the Field Museum in Chicago, set up a unique experiment to monitor the growth, birth and death of more than 250,000 tropical trees on Panama’s Barro Colorado Island.
Today the STRI Centre for Tropical Forest Science coordinates a Global Earth Observatory, a network of 20 such forest study sites in 17 countries, which maintains “actuarial tables” for more than three million trees.
Hubbell works with data from the network to develop and test his neutral theory of biodiversity – an attempt to find a unified explanation of large, complex biological systems that accurately predicts the outcome of major ecological and evolutionary forces of change.
Based on optimistic and non-optimistic scenarios for road construction in the Amazon published by the Smithsonian’s William Laurance and colleagues in the journal Science in 2004, they predict that the rare species will suffer between 37 and 50 percent extinction, whereas the extinction rate for all trees could be from 20 to 33 percent overall.
These findings were published in the Proceedings of the National Academy of Science.