新世纪研究生公共英语教材阅读 A Unit 8.ppt

Unit Eight How Trees Are Killing Our Rivers Warm-up Work in pairs and predict from the title “How trees are killing our river” what the text will be about. What problem caused a drop in water quality in almost 60 miles of Welsh rivers? What about the water quality in its tributary streams? What is the problem many streams are facing? what is the cause? How big are the plantations of conifer trees? Who has made the assessment? What is the subject of their study? What is the problem with the three conifer-forested streams? And what caused it? What fish could you find in these streams before? In which season is the daily water temperature higher in totally forested stream than that in moorland streams. What caused temperature differences? As for forested streams, which daily water temperature is lower between May and June, small ones or large ones? What is the result of the assessment? What is “biological models”? What is the result of these simulations? Where are you likely to find the same size of trout as those in moorland streams? Is this a perfect sort of biological modeling? Text Learning What problem caused a drop in water quality in almost 60 miles of Welsh rivers? acid rain What about the water quality in its tributary streams? equally degraded Text Learning What is the problem many streams are facing? And what is the cause? aquatic invertebrates and fish — a considerable decline other groups of animals — a knock-on effect water temperatures — altering densely planted conifer crops — the shading effect of the dark Text Learning Assessment of the impact of conifer plantation on stream water temperatures. Who has made the assessment? Neil Weatherley and Stephen Ormerod of the University of Wales College, Cardiff. What is the subject of their study? Year-round temperature variations in six streams Three moorland streams The other three forested streams with plantations of 30-year-old Sitka spruce. What is the problem with the three conife