NEW YORK: Destroying forests in the Amazon paves the way for hot winds to reach inside the thick forests and destroy ancient trees, according to a study on the impact of receding forest coverage.
Many of these rare tree species, and more so, plants and animals, are vanishing more quickly than anticipated because of this phenomenon, according to an international research team which carried out the study. The findings are being published in the journal Proceedings of the National Academy of Sciences USA.
The Amazon has earth's most biologically diverse tree species -- nearly 300. These precious trees are now being felled for timber operations and to create cattle ranches and industrial soy farms.
The team, led by William Laurance of the Smithsonian Tropical Research Institute in Panama, which has been studying nearly 32,000 Amazonian trees since 1980, is concerned more at the speed with which the tree communities are changing in forest fragments. Laurance said rainforest trees are capable of living for centuries, even millennia. "None of us expected things to change too fast. But in just two decades -- a wink of time for a thousand year-old tree -- the ecosystem has been seriously degraded.”
The researchers feel what contributed most for this unfortunate thing to happen is ecological changes near the margins of forest fragments. When rainforests are fragmented, hot winds from the surrounding pastures blow into the forest and kill many trees. These trees cannot just handle the stress. In addition, trees are destroyed by the strong winds that blow into the area.
Laurance says the trees that regenerate in their place are very different from the trees that died. “When you fragment a forest, the winners are common pioneer and generalist species that like forest disturbance. The losers are rare, slow-growing tree species that provide fruit, nectar and homes for a diversity of rainforest animals.”
The team studied 22 different characteristics of the increasing and declining species. A team member, Henrique Nascimento from Brazil's National Institute of Amazonian Research in Manaus, said the results indicate that tree communities in fragments are being completely restructured. "Most vulnerable are trees specialized for living in the dark forest understory that need animals such as birds or bats to disperse their seeds and pollen.”
The researchers felt fragmentation is also changing the forest's dynamics and structure. While tree communities in fragments are highly unstable, such fragments also appear to lose many of their large trees, which are replaced by small fast-growing species.
They are also concerned about the prospects of global warming that will ensue as a result of the forest fragmentation. They argue that carbon from the dead rainforest trees is broken down by microbes and fungi to become carbon dioxide.
It is estimated that 60 to 70 per cent of deforestation in the Amazon results from cattle ranches while the rest are as a result of small-scale agriculture operations.
While it has been the earth's largest rainforest and home to one-third of the planet's terrestrial species, about 650,00 square kilometers, or 18 per cent, of the forest area, have been destroyed since the 1970s. In recent years, the forests have been cleared for road construction, for agriculture and for cattle pasture, and logging.
