04/21/00 -- Big Trees Lost First in Shrinking Rainforests

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WORLDWIDE FOREST/BIODIVERSITY CAMPAIGN NEWS

Big Trees Lost First in Shrinking Rainforests

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04/21/00

OVERVIEW & COMMENTARY

"The fragmented landscape is becoming one of the most ubiquitous

features of the tropical world--and indeed, of the entire planet,"

state Laurance and Bierregaard (1997) in their Book "Tropical Forest

Remnants", which I highly recommend. Habitat loss and fragmentation

are likely to be the greatest threat to the Earth's biological

diversity and ecosystem outputs. Research into the effects of

fragmentation of tropical rainforests continues apace. Below it is

reported that where tropical forests are fragmented into a patchwork

of islands of habitat, that remaining large, ancient tropical trees

are particularly threatened. Loss of such dominant members of the

plant community has follow-on, negative cascading effects. In the

mid to long-term, widespread fragmentation of forests through

selective logging and other intrusions may be nearly as damaging

ecologically as outright deforestation. Rainforests are truly,

ecologically sustained only through preservation of large, intact

areas of habitat across landscapes. Anything less is a tree farm, a

museum or a doomed remnant.

g.b.

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Title: Big Trees Lost First in Shrinking Rainforests

Source: Reuters

Date: April 19, 2000

LONDON (Reuters) - Thousands of ancient trees in the Amazonian

rainforests which are vital for ecosystems are under threat because of

forest fragmentation, a Brazilian research group warned Wednesday.

In a letter to the science journal Nature, William Laurance of the

National Institute for Amazonian Research said large tropical trees

are unusually vulnerable in fragmented rainforests and their loss

could cause irreparable damage to plant and animal life.

The giant trees are crucial sources of fruits, flowers and shelter for

animals and influence forest structure and composition.

``Forest fragmentation in central Amazonia is having a

disproportionately severe effect on large trees, the loss of which

will have major impacts on the rainforest ecosystem,'' the researchers

said. The ecologists studied different plots within 386 square miles

of fragmented forest near Manaus in Brazil for periods of up to 20

years. They found that not only did more trees die near forest edges

but a higher proportion of the dying trees were large.

``The net result is that large trees died at a rate nearly three times

faster when they were within 300 meters (984 ft) of edges than they

did in forest interiors,'' they added.

The large trees are particularly vulnerable to uprooting and breakage

near forest edges and more prone to drought and parasites.

Laurance and his colleagues said that because the trees range in age

from a century to well over 1,000 years, their populations in

fragmented landscapes may never recover.

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