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  • A soccer-field sized patch of forest in frigid Alaska has about 40 different species of plants,

  • compared with about 70 in temperate England and 300 in the Amazonian rain forest. These

  • biodiversity differences hold true for entire countries, too: England has 1500 plant species,

  • while tropical Guyana.

  • The super-diversity of tropical rainforests is only equalled in one other type of ecosystem

  • on Earth: scrubby fire-prone shrublands that grow in western Australia and southern Africa.

  • These shrublands may not look as majestic as tropical rainforests, but in a given area,

  • theyre home to similarly stupendous numbers of species.

  • Which doesn’t necessarily mean that the rainforests and shrublands are easy places

  • for plants to live. In fact, both ecosystems owe their enormous diversity, in part, to

  • the fact that their soils have critically low supplies of nitrogen and especially phosphorus,

  • nutrients plants need in order to grow. The plant world’s leading biodiversity hotspots

  • are, quite literally, dirt poor.

  • Logically, it seems like richer soils should support more species. But in nature, as in

  • human society, ‘plenty of resourcesdoesn’t necessarily translate intoeveryone gets

  • plenty’.

  • In meadows, forests, and wetlands around the world, we consistently find more or bigger

  • plants but fewer species where soil nutrients are highest. The fastest-spreading species

  • soak up most of the extra nutrients, which lets them keep growing super fast, which lets

  • their roots suck up so much water, and their leaves snatch up so much sunlight, that other,

  • slower species actually get LESS of those resources than otherwise. So in rich soils,

  • slower species die out while the fast-growers win big.

  • On the other hand, poor soils don’t provide enough nutrient capital for fast-growing plants

  • to build their massive infrastructures and take all the resources. So poor soils inhibit

  • the greedy and allow everyone else to scrabble by. We see this pattern in human society also

  • - there’s a far greater number of businessesmostly smallin poor countries, while

  • fewer bigger companies dominate in rich countries.

  • But crummy soil isn’t the only thing that helps super high diversity blossom; for example,

  • beaches, mountaintops, and other places frequently ravaged by harsh weather or catastrophic events

  • have poor soils AND few plant species. The other major prerequisite for hyperdiversity

  • is time.

  • On most of the planet, glaciers regularly bulldoze away ecosystems and grind up mineral-rich

  • rock, creating new soil perfect for growth but not diversity. However, our high-diversity

  • rainforests and shrublands have spent millions of years beyond the reach of the ice sheets,

  • leaving their residents plenty of undisturbed time to evolve a wide variety of ingenious

  • strategies for surviving nutrient povertystrategies that have allowed for the development

  • of tall, diverse, rainforests in wet poor soils and scrubby, diverse, shrublands in

  • dry poor soils. The human landscape also seems to follow a similar pattern, with the highest

  • cultural and linguistic diversity as well as the greatest number of businesses in climatically

  • stable places where humans have been the longest and where economic resources are scarce.

  • So in some ways, the poorest places on earth are actually (also) the richest.

  • This episode of MinuteEarth is supported by the The Kwongan Foundation at the University

  • of Western Australia, which promotes the conservation of Australia's amazing biodiversity. To learn

  • more about the ecology of the hyperdiverse Kwongan ecosystem, check out Plant Life on

  • the Sandplains in Southwest Australia, or visit the Kwongan Foundation online. Thanks

  • so much to the Kwongan Foundation - and the Kwongan - for making this MinuteEarth video

  • possible.

A soccer-field sized patch of forest in frigid Alaska has about 40 different species of plants,

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為什麼貧困地區更多元? (Why Poor Places Are More Diverse)

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    Victor 發佈於 2021 年 01 月 14 日
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