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杀死非洲树木的元凶

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小编摘要:在非洲撒海尔地区有许多的树都处于垂死边缘且新的研究指出对此人类造成的气候变化应负主要的责任。此外,很多的树种也慢慢消失了。

 Climate Change Blamed for Dying African Trees



A lot of trees are dying in Africa’s Sahel region and new study says climate change caused by humans is to blame. What’s more, many tree species are also disappearing.
The study appears in the Journal of Arid Environments. Climate change scientist Patrick Gonzalez led the research on six countries. At the time of the study, Gonzalez was a visiting scholar at the Center for Forestry at the University of California at Berkley.

“We conducted our research in the African Sahel, an arid region on the edge of the Sahara where people depend on trees for survival. And the Sahel has experienced the most severe drought in the world in the modern rainfall measurement record,” he said.

The research shows that during the 20th Century rainfall in the Sahel dropped between 20 and 30 percent.

“One in six trees died in the last half of the 20th Century and, second, one in five tree species disappeared locally. And then third, together these changes shifted vegetation zones southward toward areas of more rainfall,” he said.

Possible causes of the vegetation shift include declining rainfall, growing human population and decreasing soil fertility.

“Our statistical comparison showed that climate outweighed the other factors. So, climate change was the main cause of the loss of the trees. Closer to the Sahara you have arid zone trees like Acacia with thorns. Very dry trees. And then as you move farther south towards the Equator, you have species that have fruits and hardwood and species that require more rainfall, that require moister conditions,” he said.

The study blames the climate change in the Sahel on motor vehicle and power plant emissions and other human activity over the years.

Gonzalez described conditions near the Sahara as long-term land degradation.

“So we actually are showing a form of desertification. Desertification is land degradation. We’re not showing a shift of the sands of the Sahara, but what we are showing is a degradation far south of the Sahara within the Sahel within the Sudan, within Guinea. Those are the zones south of the Sahara,” he said.

Local populations in the region have roots going back more than a thousand years and relocating is not an option. Indigenous people are adapting to climate change, for example, by caring for and pruning small trees until their mature. Such a practice can help double tree density in a field.

However, Gonzalez said local populations cannot address climate change by themselves. He says the international community must act.

“The Intergovernmental Panel on Climate Change – that’s the top scientific panel that examines climate change and I sit on that panel – has shown that we, in the United States, and other industrialized nations have it in our power using current technologies and practices to avert more drastic impacts around the world by reducing our greenhouse gas emissions,” he said.

Gonzalez was joined in the research by Compton Tucker, senior earth scientist at NASA’s Goddard Space Flight Center and Hamady Sy, Mauritania’s country representative at the Famine Early Warning Systems Network. Both NASA and the U.S. Geological Survey provided funding for the study.

杀死非洲树木的元凶


在非洲撒海尔地区有许多的树都处于垂死边缘且新的研究指出对此人类造成的气候变化应负主要的责任。此外,很多的树种也慢慢消失了。

这个研究被发表在干旱环境杂志上,研究气候变化的科学家Patrick Gonzalez在六个国家引导了此次调查研究。研究时间,Gonzalez是加州大学伯克利分校林业中心的访问学者。

他说:“我们主要在非洲撒海尔和撒海尔边缘附近的干旱区进行我们的研究,这些地方人们通常都依靠树木存活。据现代降雨量测量记录记载,撒海尔地区发生过世界最严重的旱灾。”

研究显示在20世纪期间,撒海尔的降雨下降了20%到30%。

他说:“20世纪后半期,六棵树中就有一棵树死掉,当地五个树种中就有一种消失。这些变化一起将南方植被区向更多降雨量的区域移动。”

可能造成植被转移的原因包括降雨量的下降、人口的增长以及土壤肥力的减弱。

他说:“我们统计比较得出气候比其他的因素都要重要。所以,气候变化是树木损失的主要原因。靠近撒海尔的地方有类似带刺洋槐之类的干旱区树木,是非常喜干旱的树木。当向南移动较远接近赤道时,结果实和硬树木以及需要更多降雨量的树种就会需要更加潮湿的条件才能存活。”

研究指出这应归咎于因数年机动车、电厂排放物以及其他人类活动所造成的气候变化。

Gonzalez描述撒海尔附近地区的条件是长期土地退化的结果。

他说:“所以实际上我们展示的是荒漠化的一种形式。荒漠化就是土地退化。我们要展示的不是撒海尔沙石的转变而是撒哈拉以南遥远地区包括撒海尔、苏丹和几内亚在内的荒漠化,这些地区都是撒哈拉以南的地方。”

地区当地居民的落叶归根想法已存在了千年以上,所以他们一般不会选择搬迁。原住民也不断在适应气候的变化,例如,他们照顾和修剪小树直到这些树成熟的时候,这种做法可以帮助在一个领域内成倍增加树的密度。

但是,Gonzalez说当地居民不能自己处理和应付气候的变化,国际社会必须也要开始行动。

他说:“政府间气候变化专门委员会是检查气候变化的顶级科学性的组织,该组织展示了美国和其他工业化的国家运用自己的力量使用现今的科技技术和实践通过减少温室气体的排放而避免对世界造成更加严重的影响和冲击。”

Gonzalez被美国宇航局戈达德太空飞行中心高级地质科学家和哈马迪赛,毛里塔尼亚饥荒预警网络系统的国家代表Compton Tucker相邀加入此研究。美国国家航空与宇宙航行局和地质调查所都为此项研究划拨了资金。

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2011-12-18 20:16 编辑:pliny
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