问题 问答题 简答题

气候条件在草地形成中的主导作用是如何体现的?

答案

参考答案:

(1)太阳辐射的不同,地球上形成了7个不同的热量带;即一个热带、两个温带、两个寒带、两个永冻区,并呈地带性分布;

(2)由于热量分布的地带性,决定了降水分布的地带性;从纬度地带性上看,在0-10度的范围内,年降水量为1500mm左右,随纬度的增加,降水量迅速减少,到60-90度范围时,年降水仅为270mm左右;从经度地带性上看,在同一纬度地带上随距海洋远近距离增大,降水递减;这也说明经度地带性是在纬度地带性的基础上产生的;

(3)水热条件的不同决定了植物与土壤类型的分布;如由赤道向两极,地带性植被分别为热带雨林、常绿阔叶林、季雨林、草原、荒漠等;其土壤也表现出了相应的分布系列;

(4)地球上一切生命都来源于绿色植物固定的太阳能,水热条件是形成碳水化合物的基本条件;

(5)大气因素中光、风等因子也对草地产生重要影响;影响草地生长繁殖。

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You really do have to wonder whether a few years from now we’ll look back at the first decade of the 21st century—when food prices spiked, energy prices soared, world population surged, tornados plowed through cities, floods and droughts set records, populations were displaced and governments were threatened by the confluence of it all—and ask ourselves. What were we thinking How did we not panic when the evidence was so obvious that we’d crossed some growth, climate, natural resource and population redlines all at once "The only answer can be denial," argues Paul Gilding, an Australian environmentalist, in a new book called The Great Disruption. "When you are surrounded by something so big that requires you to change everything about the way you think and see the world, then denial is the natural response. But the longer we wait, the bigger the response required."

Gilding cites the work of the Global Footprint Network, an alliance of scientists, which calculates how many "planet Earths" we need to sustain our current growth rates. G. F. N. measures how much land and water area we need to produce the resources we consume and absorb our waste, using prevailing technology. On the whole, says G. F. N. , we are currently growing at a rate that is using up the Earth’s resources far faster than they can be sustainably replenished, so we are eating into the future.

This is not science fiction. This is what happens when our system of growth and the system of nature hit the wall at once. We are now using so many resources and putting out so much waste into the Earth that we have reached some kind of limit, given current technologies. The economy is going to have to get smaller in terms of physical impact.

We will not change systems, though, without a crisis. But don’t worry, we’re getting there. We’re currently caught in two loops: One is that more population growth and more global warming together are pushing up food prices, causing political instability in the Middle East, which leads to higher oil prices, thus to higher food prices and more instability. At the same time, improved productivity means fewer people are needed in every factory to produce more stuff. So if we want to have more jobs, we need more factories. More factories making more stuff make more global warming, and that is where the two loops meet.

But Gilding is actually an eco-optimist. As the impact o the imminent Great Disruption hits us, he says, "our response will be proportionally dramatic, mobilizing as we do in war. We will change at a scale and speed we can barely imagine today, completely transforming our economy, including our energy and transport industries, in just a few short decades. " We will realize, he predicts, that the consumer-driven growth model is broken and we have to move to a more happiness-driven growth model, based on people working less and owning less.

The G. F.N. scientists()

A. have overstated the sustainability of the earth

B. are ignorant of the serious situation the earth faces

C. are overconfident about the role of current technology

D. issue a warning message about the sustainability of the earth