大意是十几年前科学家就发现 在亚马逊的老原始林仍持续在吸收空气中大量的碳 现在新的研究显示 同样的在非洲的原始森林也是持续吸收空气中 因此估计全世界热带森林固定的碳量相当於石化燃料排放碳量的5% 新闻如文末 对台湾来说有趣的是 就像 http://www.ecogarden.net/weblog/2009/02/林业经营的吊诡.html 文中说的 「对照国内有许多林业学者或林业经营单位一直以来所秉持的论点：森林中的天然林 分大部分是过熟的老龄林，生命力逐渐衰退，对增加碳贮存功效已低(1)(2)， 显然值得商榷，前者以老龄林（我比较偏爱原始林这个词）固定碳效率不佳的 理由，并趁着全球暖化议题的热潮，来处分这些原始林，有以清理地被环境、 移除枯倒木等等动作进行之（还不敢大张旗鼓的说要砍木头），姑且不论原始 林中所蕴含丰富的生物多样性不是次生林或人工林所能比拟，立论着的基础在 学理上可能就已经不成立了，期待国内的学者也针对这方面能加 以深入来研究。」 (1)http://web1.nsc.gov.tw/fp.aspx?ctNode=40&xItem=8178&mp=1 (2)http://www.forest.gov.tw/ct.asp?xItem=21104&ctNode=1584&mp=1 -------------------------------- Mmmm, Carbon! By Phil Berardelli ScienceNOW Daily News 18 February 2009 Some good news for those worried about climate change: The trees in African rainforests are gobbling up ever more carbon dioxide and thereby mitigating the buildup of the greenhouse gas in Earth's atmosphere. The finding underscores the importance of protecting the rainforests, say the authors. Trees take in CO2 as they grow, and when they die, their decay releases it back into the air. In theory, these fluxes are balanced in a mature forest, so the trees are neither a net sink--as the storage process is called--nor a source of CO2 to the atmosphere. But about 10 years ago, researchers discovered that the old-growth rainforests in the Amazon were growing enough to remove a significant amount of CO2 from the air (Science, 16 October 1998, p. 439). No one knew if the same thing was happening in Africa, home to a third of the world's tropical rainforest areas. To find out, an international team led by ecologist Simon Lewis of the University of Leeds in the U.K. has been monitoring the effects of CO2 buildup there. In this week's issue of Nature, the researchers report data from 79 plot surveys scattered across 10 African countries that included records from 1968 through 2007. Limiting their surveys to the oldest trees, those with trunks 10 centimeters in diameter or greater, they examined how the trunk size changed over time. The result: Trunks in mature forests have been expanding, adding on average 0.63 metric tons of carbon per hectare per year. That's roughly the rate seen in the Amazon and suggests that old rainforests across the tropics are taking up carbon consistently. Incorporating these first data from Africa, researchers estimate that tropical old-growth forests across the world sock away about 1.2 billion metric tons of CO2 per year, or about 5% of the world's output from fossil-fuel burning. Ecologist Helene Muller-Landau of the Smithsonian Tropical Research Institute in Balboa, Panama, says the current growth spurt of tropical rainforests, which seems puzzling on the surface, might be due to their recovery from wildfires or from deforestation by our human ancestors that occurred centuries or even millennia ago. Whatever the cause, however, she says, "there's no question we've gotten lucky," having this extra source for carbon storage. How long the luck will hold is unclear. As Lewis cautions, "these trees cannot continue growing bigger forever." The editors suggest the following Related Resources on Science sites: In Science Magazine REPORTS Changes in the Carbon Balance of Tropical Forests: Evidence from Long-Term Plots Oliver L. Phillips, Yadvinder Malhi, Niro Higuchi, William F. Laurance, Percy V. Núñez, Rodolfo M. Vásquez, Susan G. Laurance, Leandro V. Ferreira, Margaret Stern, Sandra Brown, and John Grace (16 October 1998) Science 282 (5388), 439. [DOI: 10.1126/science.282.5388.439] --

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