Unit6 carrying capacity 课文加翻译
- 格式：docx
- 大小：23.25 KB
- 文档页数：3
Unit6 carrying capacity：earth’s bottom lineIt takes no stretch of the imagination to see that thehuman species is now an agent of change of geologicproportions. We literally move mountains to mine theearth’s minerals, redirect rivers to build cities in thedesert, torch forests to make way for crops and cattle,and alter the chemistry of the atmosphere in disposing of our wastes. At humanity’s hand, the earth isundergoing a profound transformation-one withconsequences we cannot fully grasp.没有一点点想象明白人类带来地理比例的变化,我们移山开采地球的矿物质,重定向的河流在沙漠中建造城市,为了农作物和畜牧烧森林来让路,并改变大气的化学处理的废物。
对于人类,地球正在经历一个深远的改变-这一结果我们不能完全控制.It may be the ultimate irony that, in our efforts tomake the earth yield more for ourselves, we arediminishing its ability to sustain lifeof all kinds,humans included. Signs of environmental constraintsare now pervasive. Cropland is scarcely expandingany more, and a good portion of existing agriculturalland is losing fertility. Grasslands have been overgrazed and fisheries overharvested, limiting theamount of additional food from these sources. Waterbodies have suffered extensive depletion and pollution, severely restricting future food production andurban expansion. And natural forests-which helpstabilize the climate, moderate water supplies, and harbor a majority of the planet’s terrestrial biodiversity-continue to recede.它可能是最终的讽刺,在我们努力使地球产量更多,我们正在消弱其维持生命的能力。
包括人类,环境约束是现在普遍的迹象。
农田几乎扩大了,和相当一部分现有的农业土地失去肥力。
草地的过度放牧和渔业的过度捕捞，从这些来源限制额外的食物数量。
水域已经遭受大量的损耗和污染，严重地限制未来的粮食生产和城市扩张。
并且原始森林帮助稳定气候，减缓水的供应，并且保持大量地球的生物多样性，持续减弱。
These trends are not new. Human societies havebeen altering the earth since they began. But the paceand scale of degradation that started about mid-century-and continues today-is historically new. Thecentral conundrum of sustainable development isnow all too apparent: Population and economiesgrow exponentially, but the natural resources thatsupport them do not.这些趋势并不新鲜。
人类社会已经从他们开始改变地球。
但退化的速度和规模,开始于中世纪一直持续到今天，是前所未有的。
可持续发展的核心难题现在太明显:人口和经济以指数形式增长，但自然资源不能维持他们。
Biologi sts often apply the concept of “carryingcapacity” to questions of population pressures onan environment. Carrying capacity is the largestnumber of any given species that a habitat can support indefinitely. When that maximum sustainablepopulation level is surpassed, the resource basebegins to decline-sometime thereafter, so does thepopulation.生物学家通常都用的“承载能力”的概念对于环境人口压力问题。
承载能力是在一个栖息地完全维持给定任何一个物种的最大量。
当超过最大可持续人口水平时，资源基础开始下降，以后人口也会随着下降。
A simple but telling example of a breach of carrying capacity involved the introduction of twenty-nine reindeer to St.Matthew island in the bering sea in 1944.Under favorable conditions,the herd expanded to six thousand by the summer of 1963.The following winter,however,the population crashed,leaving fewer than fifty reindeer.According to a 1968 study by biologist David R.Klein of the university of Alaska,the large herd had overgrazed the island’s lichen,its main source of winter forage,and the animals faced extreme competition for limited supplies during a particularly severe winter.Klein concluded that “food supply,through its interaction with climatic factors,was the dominant population regulating mechanism for reindeer on St.Matthew Island.”一个简单而具有说服力的承载力破坏例子包括在1944年在白令海引入29驯鹿到t.Matthew岛。
在适宜的条件下，到1963年增长到6000只数量。
紧接着的冬天，人口急剧下降，不五十只驯鹿。
根据1968年由生物学家大卫·R。
克莱恩阿拉斯加大学的一项研究，岛上大量生长的苔藓，其主要的冬季饲料来源,和动物面临极端竞争对于有限的资源，在一个特别的严冬。
克莱恩认为“食物供应,通过与气候因素的互动,是主要的人口调节机制对于St.Matthew岛上的驯鹿。
”Of course,human interactions with the environment are far more complicated than those of reindeer on an island.The earth’s capacity to support humans is determined not just by our most basic food requirements but also by our levels of consumption of a whole range of resources,by the amount of waste we generate,by the technologies we choose for our varied activities,and by our success in mobilizing to deal with major threats.In recent years,the global problems of ozone depletion and greenhouse warming have underscored the danger of overstepping the earth’s ability to absorb our waste products.Less well recognized,however,are the consequences of exceeding the sustainable supply of essential resources-and how far along that course we may already be.当然，当然,人类与环境的相互作用是复杂得多比在岛上的驯鹿。
地球的承载能力维持人类不仅取决于我们最基本的食物需求，更是各种各样资源的消费水平，我们产生的废物，通过我们选择的不同技术，通过处理主要威胁来成功。
在最近几年，臭氧损耗和温室变暖的全球问题已经凸显出超越地球吸收的危险废物。
很少人意识到，然而，超越必要资源的可持续供应的结果，这个过程我们需要多久。
As a result of our population size, consumptionpatterns, and technology choices, we have surpassedthe planet’s carrying capacity. This is plainly evidentby the extent to which we are damaging and depletin g natural capital. The earth’s environmental assetsare now insufficient to sustain both our present patterns of economic activity and the life-support syterms we depend on. If current trends in resource usecontinue, and if world population grows as projected,by 2010 per capita availability of rangeland will dropby 22 percent and the fish catch by 10 percent. Together, these provide much of the world’s animalprotein. The per capita area of irrigated lend, whichnow yields about one-third of the global food harvest, will drop by I2 percent. And cropland area andforestland per person will shrink by 21 and 30 percent, respectively.由于我们的人口规模、消费模式和技术的选择,我们已经超过了地球的承载能力。
