ADAM HART-DAVIS / SCIENCE PHOTO LIBRARY. ADAM HART-DAVIS / SCIENCE PHOTO LIBRARY.
Forestry expert in Freiburg, West Germany, examining growth rings from the trunk of a Black Forest fir tree with acid rain damage. He is using a Zeiss binocular microscope with extra illumination from a desk lamp. A video camera attached to the microscope records the results. Each ring is an expression of one year's growth & reflects the growing conditions over the period. Fir trees from this area show a collapse of ring growth over the last 20 years. The rings are smaller & closer together, indicating a stunted growth history. This is linked to acid rain pollution, the lowering of pH levels in rainfall due to sulfur dioxide emissions into the air.
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