dying trees
There are several different types of air pollution. The main types are sulfur dioxide, carbon monoxide, nitrogen oxides and ozone (in the lower atmosphere). Forests react to environmental problems and pollutants in different ways. Here are some examples of forests that are dying and how air pollution affected them.
Pines in San Bernardino, California: The forest near San Bernardino consists of mostly of ponderosa pine, Jeffrey pine, sugar pine, white fir and incense cedar. The trees that were the most severely damaged were the ponderosa and the Jeffery pines. The needles on the trees began to yellow (a process called chlorosis), which led to their death. The trees were more susceptible to insects and other dangers, and their growth rate was significantly reduced. The trees near the affected pines had no similar damage, so the forest was not suffering from drought or another natural disaster or ailment or the whole forest would be equally affected. Research uncovered that the trees were being affected by the ozone coming from Los Angeles, 75 miles away from the forests. The ponderosa and Jeffery pines are especially sensitive to this pollutant.
White Pines in the eastern United States: Eastern White pines are found in southeastern Canada and eastern United States. In New England the pines are found in varying elevations, from sea level to 1200 meters in the Appalachians. Researchers noticed that in the high ozone months of June and July the pines began to show poor growth and the needles were dying. Researchers think that, with long-term exposure, white pines in these forests could die off.
Sugar Maple in the Northeast: The maples, mostly found in the Great Lake states, New England, Ontario, and Quebec have shown loss of leaves, peeling bark, and eventually, death. The decline of these trees has occurred mostly in the New England area. In Quebec, maples are dying off rapidly, and it is probably because of air pollution.
Forest declines in Central Europe: The first trees to be affected by pollution were the silver firs. They lost many needles and soon many of them began to die off. Then the needles of the Norway pines began to yellow and die. Next Pines began to show thinned needles up top and finally the hardwoods, such as beech and oak, began to show similar leaf loss. Most of the forests in West Germany have early leaf and needle loss and discoloration. Fir trees have the most extensive damage, but other trees are suffering as well.
Red Spruce and Fraser Fir in the Eastern United States: Red spruce is found in North Carolina up through Maine. The red spruce found along the eastern mountain chain is showing a decrease in growth and a high death rate. The branch tips begin to die and the top needles turn yellow and die. This trend continues wherever the trees are found. Over the past 25 years these species have declined by half in the Northeast.
related topics
[dry coniferous forests] [temperate forests] [broadleaf forests]

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