大意是十幾年前科學家就發現 在亞馬遜的老原始林仍持續在吸收空氣中大量的碳 現在新的研究顯示 同樣的在非洲的原始森林也是持續吸收空氣中 因此估計全世界熱帶森林固定的碳量相當於石化燃料排放碳量的5% 新聞如文末 對台灣來說有趣的是 就像 http://www.ecogarden.net/weblog/2009/02/林業經營的弔詭.html 文中說的 「對照國內有許多林業學者或林業經營單位一直以來所秉持的論點：森林中的天然林 分大部分是過熟的老齡林，生命力逐漸衰退，對增加碳貯存功效已低(1)(2)， 顯然值得商榷，前者以老齡林（我比較偏愛原始林這個詞）固定碳效率不佳的 理由，並趁著全球暖化議題的熱潮，來處分這些原始林，有以清理地被環境、 移除枯倒木等等動作進行之（還不敢大張旗鼓的說要砍木頭），姑且不論原始 林中所蘊含豐富的生物多樣性不是次生林或人工林所能比擬，立論著的基礎在 學理上可能就已經不成立了，期待國內的學者也針對這方面能加 以深入來研究。」 (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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