Bill, At issue here is really why we care about rain forest removal. Within the lens of a carbon-cycle or Climate Change debate, we care about them because they represent large carbon stocks that are kept out of the atmosphere. Of course there is an important difference between the term carbon "stock" and carbon "sink." The article mentions that young forests tend to sequester CO2 out of the atmosphere at greater rates than their mature counterparts, and this is absolutely correct. The same phenomena is observed in nearly all forest ecotypes, be they temperate or tropical, and makes sense given the intense vertical competition incurred in early forest development. Early forests are impressive carbon sinks. Mature forests have large carbon stocks. Foresters have indirectly understood this for years from a biomass point of view, limiting their rotations to 25-35-50 years and harvesting the timber when it reached a threshold whereby the slowing rate of growth made biomass gains less profitable.
Mature rain forests are not large carbon sinks. At this stage the increasing respiration generated by older slower-growing trees, and soil micro-organisms offsets many of the gains of photosynthesis. Surprising ecosystems like Mangrove forests and sub-alpine forests remain sinks in maturity because of respiration limitations: in Mangroves, anoxia limits soil respiration, and in sub-alpine forests, cold and water stress limit soil respiration. Sinks or Stocks. What do we care about? At it's simplest, we should probably most care about stocks, as this represents carbon unavailable to the atmosphere. The other argument about whether a young forest functions in the same capacity as a Mature forest is a different matter. There are probably not too many people on this list that would argue that a primary stand delivers the same biogeochemical, ecological, hydrologic, and energy balance properties observed in a Mature stand. A value decision about what is "good enough" then comes into play. That's when things get sticky. You may have heard about the "North American Carbon Sink," which is largely due to the recovery of our once heavily-logged forests over the last century or so. This does not mean that the biomass of North American forests is somehow holding as much Carbon as it was in pre-colonial times. It simply means that there has been some recovery, as there now seems to be in certain areas of the rain forest (though not enough to completely mitigate the effects of initial deforestation). Mature forests hold more carbon in the Biosphere. If it's not there, you can bet that much of it is circulating in the atmosphere. DM On Sat, Jan 31, 2009 at 5:21 AM, Bill Silvert <[email protected]> wrote: > I was intrigued to see this in the New York Times. I have no background > in this area and would be interested in seeing what more knowledgable > list members might have to say. > > Also I recently heard a statement that there is a significant amount of > anaerobic decomposition under old growth forests that should be factored > into calculations of biogeochemical fluxes, and it would be interesting > to hear about that too. > > Bill Silvert > > > January 30, 2009 > > New Jungles Prompt a Debate on Rain Forests > By [LINK: > > http://query.nytimes.com/search/query?ppds=bylL&v1=ELISABETH%20ROSENTHAL&fdq=19960101&td=sysdate&sort=newest&ac=ELISABETH%20ROSENTHAL&inline=nyt-per > ] > ELISABETH ROSENTHAL > > > CHILIBRE, [LINK: > > http://topics.nytimes.com/top/news/international/countriesandterritories/panama/index.html?inline=nyt-geo > ] > 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 [LINK: > > http://topics.nytimes.com/top/news/science/topics/forests_and_forestry/rain_forests/index.html?inline=nyt-classifier > ] > 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 [LINK: > > http://topics.nytimes.com/top/news/science/topics/globalwarming/index.html?inline=nyt-classifier > ] > 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 [LINK: > > http://topics.nytimes.com/top/reference/timestopics/organizations/s/smithsonian_institution/index.html?inline=nyt-org > ] > Smithsonian Institution and the [LINK: > > http://topics.nytimes.com/top/reference/timestopics/organizations/u/united_nations/index.html?inline=nyt-org > ] > 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. > > 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 [LINK: > > http://topics.nytimes.com/top/news/international/countriesandterritories/brazil/index.html?inline=nyt-geo > ] > 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. > > [LINK: http://www.nytimes.com/ref/membercenter/help/copyright.html] > Copyright 2009 [LINK: http://www.nytco.com/] The New York Times Company >
