森林大火使美国“碳仓库”减少

时间：2012-07-26 05:38:45

（单词翻译:单击）

Forests in the Pacific Northwest store more carbon than any other region in the United States, but our warming climate may undermine their storage potential. A new study conducted by the U.S. Forest Service's Pacific Northwest Research Station and the Climate Impacts Group at the University of Washington has found that, by 2040, parts of Washington State could lose as much as a third of their carbon stores, as an increasing area of the state's forests is projected to be burned by wildfire. The study -- published in the July 2012 issue of the journal Ecological1 Applications -- is the first to use statistical2 models and publicly available Forest Inventory3 and Analysis data to estimate the effects of a warming climate on carbon storage and fluxes4（流量，流动） on Washington's forests.

 
"When considering the use of forests to store carbon, it will be critical to consider the increasing risk of wildfire," said Crystal Raymond, a research biologist based at the station's Pacific Wildland Fire Sciences Laboratory and lead author of the study. "Especially in the West, where climate-induced changes in fire are expected to be a key agent of change."
 
Trees remove and sequester5（使隔绝） carbon from the atmosphere, in the form of carbon dioxide, acting6 as important stores, or "sinks," of carbon that help to offset7 its accumulation in the atmosphere. When trees and other woody material in the forest are burned by fire, they release carbon back to the atmosphere, mostly as carbon dioxide, where it may once again act as a greenhouse gas that promotes warming. This land-atmosphere exchange of carbon is increasingly of interest to land managers seeking ways to actively8 manage forests to store carbon and help mitigate9（减轻，缓和） greenhouse gases.
 
To explore what effect climate-driven changes in wildfire might have on the ability of Washington's forests to act as carbon sinks, Raymond and station research ecologist Don McKenzie used a novel approach. They combined published forest-inventory data, fire-history data, and statistical models of area burned to estimate historical and future carbon carrying capacity of three regions in Washington -- the Western Cascades11, the Eastern Cascades, and the Okanogan Highlands -- based on potential forest productivity and projections12 of 21st century area burned.
 
"Forests on both the eastern and western slopes of the Cascade10 Range will lose carbon stored in live biomass because area burned across the state is expected to increase," Raymond said. "Even small increases in area burned can have large consequences for carbon stored in living and dead biomass."
 
The researchers looked at live biomass, which includes living trees and vegetation, as well as nonliving biomass in the form of coarse woody debris13, which includes dead standing14 trees and downed logs. Both contribute to the carbon cycle, but in different ways -- living biomass removes carbon from the atmosphere as vegetation grows, and coarse woody debris releases carbon over time as the material decomposes15.
 
Raymond and McKenzie projected forests of the Western Cascades to be most sensitive to climate-driven increases in fire, losing anywhere from 24 to 37 percent of their live biomass and from 15 to 25 percent of their coarse woody debris biomass by 2040. These forests store significant carbon and typically burn with high severity, killing16 many trees and consuming coarse（粗糙的） woody debris.
 
On the other side of the mountains, the researchers also projected a decrease in live biomass by 2040 -- of anywhere between 17 and 26 percent in the Eastern Cascades and in the Okanogan Highlands -- but no change in coarse woody debris biomass, or possibly even an increase, because coarse woody debris biomass increases as trees are killed by fire and subsequent low-severity fires burn only a small portion of it.
 
"Changes in fire regimes in a warming climate can limit our potential to use forests in the Pacific Northwest to store additional carbon and to reduce atmospheric17 carbon dioxide," Raymond said.
 
Understanding the possible effects of more area burned by fire can help managers decide whether forests need to be actively managed for their fire potential to minimize carbon loss.

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1 ecological IrRxX     
adj.生态的，生态学的
参考例句：
  • The region has been declared an ecological disaster zone.这个地区已经宣布为生态灾难区。
  • Each animal has its ecological niche.每种动物都有自己的生态位.
2 statistical bu3wa     
adj.统计的，统计学的
参考例句：
  • He showed the price fluctuations in a statistical table.他用统计表显示价格的波动。
  • They're making detailed statistical analysis.他们正在做具体的统计分析。
3 inventory 04xx7     
n.详细目录，存货清单
参考例句：
  • Some stores inventory their stock once a week.有些商店每周清点存货一次。
  • We will need to call on our supplier to get more inventory.我们必须请供应商送来更多存货。
4 fluxes fe973c05de3ff6dd2396188728b29a39     
连续的改变( flux的名词复数 )； 不稳定的状态； 不停的变化； 通量
参考例句：
  • In general, fluxes and forces may have different tensorial characters. 一般说来，力和通量可以具有不同的张量特征标。
  • The parameterized eddy fluxes simulatedthe seasonal and latitudinal variations reasonably well. 模拟出涡动通量的空间分布和时间变化。
5 sequester Czhw5     
vt.使退隐，使隔绝
参考例句：
  • Everything he owned was sequestered.他的所有财产都被扣押了。
  • This jury is expected to be sequestered for at least two months.预计这个陪审团将至少被隔离两个月。
6 acting czRzoc     
n.演戏，行为，假装；adj.代理的，临时的，演出用的
参考例句：
  • Ignore her,she's just acting.别理她，她只是假装的。
  • During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。
7 offset mIZx8     
n.分支，补偿；v.抵消，补偿
参考例句：
  • Their wage increases would be offset by higher prices.他们增加的工资会被物价上涨所抵消。
  • He put up his prices to offset the increased cost of materials.他提高了售价以补偿材料成本的增加。
8 actively lzezni     
adv.积极地，勤奋地
参考例句：
  • During this period all the students were actively participating.在这节课中所有的学生都积极参加。
  • We are actively intervening to settle a quarrel.我们正在积极调解争执。
9 mitigate EjRyf     
vt.（使）减轻，（使）缓和
参考例句：
  • The government is trying to mitigate the effects of inflation.政府正试图缓和通货膨胀的影响。
  • Governments should endeavour to mitigate distress.政府应努力缓解贫困问题。
10 cascade Erazm     
n.小瀑布，喷流；层叠；vi.成瀑布落下
参考例句：
  • She watched the magnificent waterfall cascade down the mountainside.她看着壮观的瀑布从山坡上倾泻而下。
  • Her hair fell over her shoulders in a cascade of curls.她的卷发像瀑布一样垂在肩上。
11 cascades 6a84598b241e2c2051459650eb88013f     
倾泻( cascade的名词复数 )； 小瀑布（尤指一连串瀑布中的一支）； 瀑布状物； 倾泻（或涌出）的东西
参考例句：
  • The river fell in a series of cascades down towards the lake. 河形成阶梯状瀑布泻入湖中。
  • Turning into the sun, he began the long, winding drive through the Cascades. 现在他朝着太阳驶去，开始了穿越喀斯喀特山脉的漫长而曲折的路程。 来自英汉文学 - 廊桥遗梦
12 projections 7275a1e8ba6325ecfc03ebb61a4b9192     
预测( projection的名词复数 )； 投影； 投掷； 突起物
参考例句：
  • Their sales projections are a total thumbsuck. 他们的销售量预测纯属估计。
  • The council has revised its projections of funding requirements upwards. 地方议会调高了对资金需求的预测。
13 debris debris     
n.瓦砾堆，废墟，碎片
参考例句：
  • After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
  • Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上，导致蛀牙。
14 standing 2hCzgo     
n.持续，地位；adj.永久的，不动的，直立的，不流动的
参考例句：
  • After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
  • They're standing out against any change in the law.他们坚决反对对法律做任何修改。
15 decomposes 104d7ddd5cfb119e99319744ced0efe9     
腐烂( decompose的第三人称单数 )； （使）分解； 分解（某物质、光线等）
参考例句：
  • The debris slowly decomposes into compost. 这些垃圾慢慢地分解成了堆肥。
  • Plastic is a substance that hardly decomposes in the nature. 塑料是一种在自然中极难降解的物质。
16 killing kpBziQ     
n.巨额利润；突然赚大钱，发大财
参考例句：
  • Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
  • Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。
17 atmospheric 6eayR     
adj.大气的，空气的；大气层的；大气所引起的
参考例句：
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

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