跪求两篇关于生物多样性和食物链的英语论文.每篇600字左右.

第一篇：
Biodiversity is the variety and variability of life on Earth.This includes all of the plants and animals that live and grow on the Earth,all of the habitats that they call home,and all of the natural processes of which they are a part.The earth supports an incredible array of biodiversity—from Thailand’s tiny bumblebee bat to the ocean’s great blue whale—with plants and animals of all shapes and sizes in between.This fantastic variety of life is found in diverse habitats ranging from the hottest desert to tropical rainforests to the arctic tundra.Biodiversity is essential to every aspect of the way that humans live around the world.Plants and animals provide people with food and medicine,trees play an important role in absorbing greenhouse gases and cleaning the air we breathe,and rivers and watersheds provide the clean water that we drink.
Unfortunately,the earth’s biodiversity is disappearing,with an estimated 1,000 species per year becoming extinct.Conserving biodiversity is especially crucial in developing countries where people’s livelihoods are directly dependent on natural resources such as forests,fisheries and wildlife.
第二篇：
Plants and animals provide people with food and medicine.Forty percent of all prescriptions written today are composed from the natural compounds found in different species.An estimated 80,000 edible plants are found in the world,and one in every three mouthfuls of the food you swallow is prepared from plants pollinated by wild insects and animals.The extinction of each additional species results in the irreversible loss of unique genetic materials,each of which has potential for development of medicines and foods and associated enterprises that create jobs.
While plants and animals keep you well fed and healthy,trees play an important role in absorbing greenhouse gases.Through photosynthesis,trees absorb and store atmospheric carbon,helping to combat global warming and purifying the air we breathe.Forests also control soil erosion and purify water.
As natural systems breakdown,people around the world are forced to find alternative and often more costly ways to maintain adequate supplies of clean water or to deal with increasingly polluted air.The net economic benefits of biodiversity are estimated to be at least $3 trillion per year,or 11 percent of the annual world economic output.