One of the most remarkable things about rainforest plant life is its diversity. The temperate rainforests of the Pacific Northwest are mainly composed of a dozen or so tree species. A tropical rainforest, on the other hand, might have 300 distinct tree species.
All Creatures, Great and Small
Rainforests are home to the majority of animal species in the world. And a great number of species who now live in other environments, including humans, originally inhabited the rainforests. Researchers estimate that in a large rainforest area, there may be more than 10 million different animal species.
Most of these species have adapted for life in the upper levels of the rainforest, where food is most plentiful. Insects, which can easily climb or fly from tree to tree, make up the largest group(ants are the most abundant animal in the rainforest).Insect species have a highly symbiotic relationship with the plant life in a rainforest. The insects move from plant to plant, enjoying the wealth of food provided there. As they travel, the insects may pick up the plants' seeds, dropping them some distance away. This helps to disperse the population of the plant species over a larger area.
The numerous birds of the rainforest also play a major part in seed dispersal. When they eat fruit from a plant, the seeds pass through their digestive system. By the time they excrete (排泄) the seeds, the birds may have flown many miles away from the fruit-bearing tree.
There are also a large number of reptiles and mammals in the rainforest. Since the weather is so hot and humid during the day, most rainforest mammals are active only at night, dusk or dawn. The many rainforest bat species are especially well adapted for this lifestyle. Using their sonar, bats navigate easily through the mass of trees in the rainforest, feeding on insects and fruit.
While most rainforest species spend their lives in the trees, there is also a lot of life on the forest floor. Great apes, wild pigs, big cats and even elephants can all be found in rainforests. There are a number of people who live in the rainforests, as well. These tribes - which, up until recently, numbered in the thousands - are being forced out of the rainforests at an alarming rate because of deforestation.
Deforestation
In the past hundred years, humans have begun destroying rainforests at an alarming rate. Today, roughly 1.5 acres of rainforest are destroyed every second. People are cutting down the rainforests in pursuit of three major resources：
• Land for crops
• Lumber for paper and other wood products
• Land for livestock pastures
In the current economy, people obviously have a need for all of these resources. But almost all experts agree that, over time, we will suffer much more from the destruction of the rainforests than we will benefit.
相关推荐：
别被四六级快速阅读吓倒 过关只需两个技巧 英语六级阅读最后冲刺：名师解答常见难题
