 CHILIBRE, Panama
— The land where Marta Ortega de Wing raised hundreds of pigs until 10
years ago is being overtaken by galloping jungle — palms, lizards and
ants.
Instead of farming, she now shops at the supermarket and her grown
children and grandchildren live in places like Panama City and New
York. Here, and in other tropical countries around the world,
small holdings like Ms. Ortega de Wing’s — and much larger swaths of
farmland — are reverting to nature, as people abandon their land and
move to the cities in search of better livings. These new
“secondary” forests are emerging in Latin America, Asia and other
tropical regions at such a fast pace that the trend has set off a
serious debate about whether saving primeval rain forest
— an iconic environmental cause — may be less urgent than once thought.
By one estimate, for every acre of rain forest cut down each year, more
than 50 acres of new forest are growing in the tropics on land that was
once farmed, logged or ravaged by natural disaster. “There is
far more forest here than there was 30 years ago,” said Ms. Ortega de
Wing, 64, who remembers fields of mango trees and banana plants. The
new forests, the scientists argue, could blunt the effects of rain
forest destruction by absorbing carbon dioxide, the leading
heat-trapping gas linked to global warming, one crucial role that rain forests play. They could also, to a lesser extent, provide habitat for endangered species. The
idea has stirred outrage among environmentalists who believe that
vigorous efforts to protect native rain forest should remain a top
priority. But the notion has gained currency in mainstream
organizations like the Smithsonian Institution and the United Nations,
which in 2005 concluded that new forests were “increasing dramatically”
and “undervalued” for their environmental benefits. The United Nations
is undertaking the first global catalog of the new forests, which vary
greatly in their stage of growth. “Biologists were ignoring
these huge population trends and acting as if only original forest has
conservation value, and that’s just wrong,” said Joe Wright, a senior
scientist at the Smithsonian Tropical Research Institute here, who set
off a firestorm two years ago by suggesting that the new forests could
substantially compensate for rain forest destruction. “Is this a
real rain forest?” Dr. Wright asked, walking the land of a former
American cacao plantation that was abandoned about 50 years ago, and
pointing to fig trees and vast webs of community spiders and howler
monkeys. “A botanist can look at the trees here and know this is
regrowth,” he said. “But the temperature and humidity are right. Look
at the number of birds! It works. This is a suitable habitat.”
Dr. Wright and others say the overzealous protection of rain forests
not only prevents poor local people from profiting from the rain
forests on their land but also robs financing and attention from other
approaches to fighting global warming, like eliminating coal plants.
But other scientists, including some of Dr. Wright’s closest
colleagues, disagree, saying that forceful protection of rain forests
is especially important in the face of threats from industrialized
farming and logging. The issue has also set off a debate over
the true definition of a rain forest. How do old forests compare with
new ones in their environmental value? Is every rain forest sacred? “Yes,
there are forests growing back, but not all forests are equal,” said
Bill Laurance, another senior scientist at the Smithsonian, who has
worked extensively in the Amazon. He scoffed as he viewed Ms.
Ortega de Wing’s overgrown land: “This is a caricature of a rain
forest!” he said. “There’s no canopy, there’s too much light, there are
only a few species. There is a lot of change all around here whittling
away at the forest, from highways to development.” While new
forests may absorb carbon emissions, he says, they are unlikely to save
most endangered rain-forest species, which have no way to reach them.
Everyone, including Dr. Wright, agrees that large-scale rain-forest
destruction in the Amazon or Indonesia should be limited or managed.
Rain forests are the world’s great carbon sinks, absorbing the
emissions that humans send into the atmosphere, and providing havens
for biodiversity. At issue is how to tally the costs and
benefits of forests, at a time when increasing attention is being paid
to global climate management and carbon accounting. Just last month, at climate talks held by the United Nations in
Poznan, Poland, the world’s environment ministers agreed to a new
program through which developing countries will be rewarded for
preventing deforestation. But little is known about the new forests —
some of them have never even been mapped — and they were not factored
into the equation at the meetings.
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Tito Herrera for The New York Times
FADING WAYS Gumercinto Vásquez said it was hard to find work in Chilibre because so many farms had been abandoned.
Dr. Wright and other scientists say they should be. About 38 million
acres of original rain forest are being cut down every year, but in
2005, according to the most recent “State of the World’s Forests
Report” by the United Nations Food and Agriculture Organization, there
were an estimated 2.1 billion acres of potential replacement forest
growing in the tropics — an area almost as large as the United States.
The new forest included secondary forest on former farmland and
so-called degraded forest, land that has been partly logged or
destroyed by natural disasters like fires and then left to nature. In
Panama by the 1990s, the last decade for which data is available, the
rain forest is being destroyed at a rate of 1.3 percent each year. The
area of secondary forest is increasing by more than 4 percent yearly,
Dr. Wright estimates. With the heat and rainfall in tropical
Panama, new growth is remarkably fast. Within 15 years, abandoned land
can contain trees more than 100 feet high. Within 20, a thick
rain-forest canopy forms again. Here in the lush, misty hills, it is
easy to see rain-forest destruction as part of a centuries-old cycle of
human civilization and wilderness, in which each in turn is cleared and
replaced by the other. The Mayans first cleared lands here that are now
dense forest. The area around Gamboa, cleared when the Panama Canal was
built, now looks to the untrained eye like the wildest of jungles.
But Dr. Laurance says that is a dangerous lens through which to view
the modern world, where the forces that are destroying rain forest
operate on a scale previously unknown. Now the rain forest is
being felled by “industrial forestry, agriculture, the oil and gas
industry — and it’s globalized, where every stick of timber is being
cut in Congo is sent to China and one bulldozer does a lot more damage
than 1,000 farmers with machetes,” he said. Globally,
one-fifth of the world’s carbon emissions come from the destruction of
rain forests, scientists say. It is unknown how much of that is being
canceled out by forest that is in the process of regrowth. It is a
crucial but scientifically controversial question, the answer to which
may depend on where and when the forests are growing. Although
the United Nations’ report noted the enormous increase of secondary
forests, it is unclear how to describe or define them. The 2.1 billion
acres of secondary forests includes a mishmash of land that has the
potential to grow into a vibrant faux rain forest and land that may
never become more than a biologically shallow tangle of trees and weeds.
“Our knowledge of these forests is still rather limited,” said Wulf
Killmann, director of forestry products and industry at the United
Nations agriculture organization. The agency is in the early phases of
a global assessment of the scope of secondary forest, which will be
ready in 2011. The Smithsonian, hoping to answer such questions,
is just starting to study a large plot of newly abandoned farmland in
central Panama to learn about the regeneration of forests there. Regenerated
forests in the tropics appear to be especially good at absorbing
emissions of carbon, but that ability is based on location and rate of
growth. A field abandoned in New York in 1900 will have trees shorter
than those growing on a field here that was abandoned just 20 years
ago. For many biologists, a far bigger concern is whether new
forests can support the riot of plant and animal species associated
with rain forests. Part of the problem is that abandoned farmland is
often distant from native rain forest. How does it help Amazonian
species threatened by rain-forest destruction in Brazil if secondary forests grow on the outskirts of Panama City? Dr.
Wright — an internationally respected scientist — said he knew he was
stirring up controversy when he suggested to a conference of tropical
biologists that rain forests might not be so bad off. Having lived in
Panama for 25 years, he is convinced that scientific assessments of the
rain forests’ future were not taking into account the effects of
population and migration trends that are obvious on the ground.
In Latin America and Asia, birthrates have dropped drastically; most
people have two or three children. New jobs tied to global industry, as
well as improved transportation, are luring a rural population to
fast-growing cities. Better farming techniques and access to seed and
fertilizer mean that marginal lands are no longer farmed because it
takes fewer farmers to feed a growing population. Gumercinto
Vásquez, a stooped casual laborer who was weeding a field in Chilibre
in the blistering sun, said it had become hard for him to find work
because so many farms had been abandoned. “Very few people around here are farming these days,” he said. Dr.
Wright, looking at a new forest, sees possibility. He says new research
suggests that 40 to 90 percent of rain-forest species can survive in
new forest. Dr. Laurance focuses on what will be missing, ticking off species like jaguars, tapirs and a variety of birds and invertebrates. While he concedes that a regrown forest may absorb some carbon, he insists, “This is not the rich ecosystem of a rain forest.” Still,
the fate of secondary forests lies not just in biology. A global
recession could erase jobs in cities, driving residents back to the
land. “Those are questions for economists and politicians, not us,” Dr. Wright said.
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