Presented to the
Oakland City University
In Partial Fullfillment
of the requirements of
Physical Science (PHSC 101)
November 30, 2010
Forests of Canada, the United States and Scandinavia have a huge economic importance. Hundreds of thousands of people are employed by the various industries associated with timber andforest. One in 10 Canadians work directly or indirectly in these industries, and Sweden and Norway have a similar job profile. Furthermore, forests and lakes of these countries are major tourist and recreational areas. Acid rain poses an insidious and potentially devastating threat to our forests. It has been shown that the rain moderately acidic damages plants newborn.
Researchers are beginningto assess the role of acid rain in increasing vulnerability of trees to disease and insects. There was no direct and visible damage to foliage by acid rain, but the dramatic and surprising death and wilting of trees in central Europe is a catalyst for these concerns. Thousands of acres of spruce-fir forests in Czechoslovakia and East Germany were killed in the past 20 years. The forests of theHartz Mountains and the Black Forest of West Germany also have problems, as the beech and spruce trees die or their growth is reduced by less buffered soils. Since 1990 he has observed a recovery of spruce forests.
According to Ulrich Bernhardt (University of Göttingen, Germany), increased acidity of rain in Germany over the past 25 years, combined with the strong and acidic snow in mountainousareas, has caused landslide of calcium and magnesium in the soil, the same time, increased the concentration of aluminum in soil solutes. Consequently, the proportion has decreased Ca / Al. When this molar ratio is less than 1.0 favors the incorporation of aluminum in the fine feeder roots, which expresses the toxicity of this element, capable of killing the roots and reduce its force.
The incidenceof high concentrations of aluminum in the soil solution has been particularly evident for years, which have produced severe summer droughts, as in 1975 and 1976 in Europe. In these circumstances, the aluminum concentration increases as a result of the concentration of solutes in soil induced by drought. No doubt the rate of decline of forests in western Germany has accelerated markedly since1975. It is thought that the high level of industrial activity in West Germany and its surroundings is a key factor in this, as is the high rainfall in mountainous areas, where the effects are more severe. In the high altitude forests, the waters of acid clouds surrounding the trees in fog for long periods each year.
One of the biggest challenges we face in studying the forest growth and possibleeffects of acid rain in this is the very considerable annual variation in growth, caused by normal climate fluctuations and insect attack. Growth may differ in various points from one year to another. It is therefore very difficult to identify small trends in reducing forest growth in a short period. Evaluations of this type have been based on the width of the wood placed in the trunks of trees eachyear in the form of rings. This kind of studies have been conducted in the United States and Norway.
They have all used limited amounts of data, have struggled to account for normal growth at different ages within a species, and have not reached conclusions. A U.S. study suggests that "acid rain deserves important consideration as a factor suppressing growth in the Pine Barrens of New Jersey",but others suggest that it is impossible to draw conclusions based on that data. Thus, we have a very frustrating situation in which we could be facing a severe reduction of force forest, but at present we are unable to marshal the various alternative explanations.
Although the sensitivity to direct foliar damage by acid rain in some crops appears to be greater than that of many tree species,...