热带稀树草原翻译

For instance, because a dense, impermeable subsoil retains water near the surface, savannas occur in areas of southwest Africa that would otherwise support only desert. 例如,密集的不可渗透的土壤使水留在土表,不 能渗透下去.因此稀树草原大多在非州西南部 或者沙漠.
（热带稀树草原气候通常比热带干旱森林干燥。然而, 委内瑞拉的圣费尔南多获得和热带干旱森林一样多的 降雨量，而其他地区和热带稀树草原一样，和沙漠一 样的干燥。是什么阻止潮湿的热带稀树草原被森林取 代、是什么让它在如同沙漠般的条件下坚持？答案在 草原深
土壤
Soil layers with low permeability to water play a key role in maintaining many tropical savannas. 低渗的土壤对热带稀树草原的存在起着很关键 的作用.

热带稀树草原的自然植被 和北部澳大利亚南部的热 带旱生林的自然植被一样 多。稀树草原也是南亚的 一种自然植被。（这里的 南亚仅仅指在巴基斯坦东 部和印度西北部的梧桐河 以东的南亚）
CLIMATE
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TROPICAL SAVANNA GEOGRAPHY AND CLIMATE

One difference is that trees don’t completely dominate the landscape. Consequently, a greater proportion of the biological activity on the savanna takes place near ground level. 其一是树木不能完全影响地形，因此生物的活 动范围大多在地面。

大多数热带稀树草原分 布在热带干旱林的南部 或者北部，也就是南北 纬10°-20°的赤道地区。 在撒哈拉沙漠以南的非 洲，热带稀树草原出现 在巴西的中南部，委内 瑞拉和哥伦比亚。

In Africa south of the Sahara Desert,tropical savannas extend from the west to the east coasts,cut a north-south swath across the east African high-lands,and reappear in southcentral Africa(fig.2.16)

Impermeable soils also help savannas persist in wet areas ,particularly in South America. Trees do not move onto savannas where an impermeable subsoil keeps surface soils waterlogged during the wet season. 在潮湿的地方稀树草原也能存在，是因为不可 渗透的土壤在雨季使得水只能浸润表土，从而 树种不能在这生根发芽，例如美国南部。

The wandering consumers of the Australian savannas include kangaroos, large flocks of birds, and, for about 50000 years,humans. 在澳大利亚稀树草原上这些动物包括袋鼠和大 量的鸟类以及约50000年前的人类。

This lightning often starts fires, particularly at the beginning of the wet season when the savanna is tinder(火绒，易燃物). These fires kill young trees while the grasses survive and quickly re sprout. Consequently, fires help maintain the tropical savanna as a landscape of grassland and scattered(分散的，零乱的) trees. (通常闪电开始于火灾,尤其是在雨季的开始时,稀 树草原是火种，这些火灾杀死小树而草得到生存并 且快速重新发芽。因此,火灾有助于维持热带稀树 大草原上作为一种景观的草原和稀少的树木）

In these landscapes, scattered trees occur only where soils are well drained. 在稀树草原里，稀疏的树木只生活在土壤疏松 水分足够的地方。

生物
As you gaze out across the savanna landscape, think back to the tropical rain forest and dry forest. How is the savanna different? 当你遥望稀树草原的地形时，回想热带雨林与 热带旱林，热带稀树草原有何不同？

The tropical savanna is populated by wandering animals that move in response to seasonal and year-to-year variations in rainfall and food availability. 热带稀树草原里生活着许多迁徙的动物，这些 动物随着降雨量和食物的季节性变化而迁移。


The tropical savanna is the kingdom of the farsighted ,the stealthy,and the swift and is the birthplace of humankind.It was from here that we eventually moved out into every biome.Though most humans live away from this first home,the fascinamon continues.

在热带稀树草原，更适 合能远视的动物，善于 潜伏的动物和动作敏捷 的动物生存，并且它是 人类的发源地。也是在 这里我们最终形成一个 生物群系。尽管大部分 人类居住的地方离热带 稀树草原很远，但人类 仍旧关注着热带稀树草 原。
GEOGRAPHY

Most tropical savannas occur north and south of tropical dry forests within 10°to 20°of the equator.In Africa south of the Sahara Desert,tropical savannas occur in south-central Brazil and cover a great deal of Venezuela and Columbia.

在非洲南部的撒哈拉大 沙漠，热带稀树草原从 西部延伸到东海岸，穿 越东非大土地南北大片， 并重新出现在中南部非 洲.

Tropical savannas are also the natural vegetation and of much of northern Australia in the region just south of the tropical dry forest.Savanna is also the natural vegetation of an area in southern Asia just east of the Indus River in eastern Pakistan and northwestern India.
TROPICAL SAVANNA 热带稀树草原
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Stand in the middle of a savanna,a tropical grassland dotted with scattered trees ,and your eye will be drawn to the horizon for the approach of thunderstroms or wandering herds of wildlife .(fig.2.15)
热带稀树草原的地理和气候

As in the tropical dry forest, life on the savanna cycles to the rhythms of alternating dry and wet seasons. Here, however, seasonal drought(干旱) combines with another important physical factor, fire. The rains come in summer and are accompanied by intense lightning. （和热带干旱森林一样,稀树草原上的生命在干燥 和潮湿的季节中有节奏的周期交替着。然而，在这 里季节性干旱和另一个重要的物理因素有关----火灾。 夏季雨来临时都伴随着闪电）

During droughts, some of these Australian species travel thousands of kilometers in search of suitable conditions. 在旱季，一些澳大利亚的迁移生物会穿越上千 千米的距离去寻找适合生存的环境。

Frequent, fires have selected for fire resistance in the savanna flora. The few tree species on the savanna resist fire well enough to be unaffected by low-intensity fires. 常见的火灾都用稀树草原里的树木抗火，因为 许多稀树草原里面的树木都不会被低温的火燃 烧。