The Effects of Carbon Dioxide on Tree Growth in the Oxford Area
This topic submitted by Shawn Seiler ( silo610@hotmail.com ) on 4/6/00 .
Research proposal—
Oxford is situated in a temperate zone. In a temperate zone, growth may be limited by extremely low temperatures and extremely low precipitation. Unlike areas in the Southwest (Arizona, New Mexico, etc.) where precipitation is the limiting factor in tree growth, the temperate areas have a long vegetative period and ample rainfall throughout the year. The growth in tree rings in this area is usually complacent, so periods of drought or cold will stand out. Since the industrial revolution, there has been a well-recorded large increase in the amount of carbon dioxide. Carbon dioxide is essential for plant growth. As, everyone knows carbon dioxide is also a major greenhouse gas and the increased emissions may be adversely affecting the world’s climate. However, the net warming effect on climate may be beneficial to plant growth. I believe that the increase in carbon dioxide emissions have had a positive effect on the growth of trees and this positive effect will negate any periods of drought or excessive coldness that might otherwise have hindered tree growth.
Forest have been known be a carbon sink. Through the burning of fossil fuels and wood the amount of greenhouse gases have increased somewhat constantly since the industrial revolution. Research has shown that as greenhouse gases have increased, so has the average temperature of the world’s climate. Research has also shown that increased CO2 in the air increases the rate at which plants grow. One study shows in a 650ppm CO2 environment compared to a 350 ppm CO2 environment, the plants grown in the 650 ppm CO2 have 60% higher total dry weight than in the ambient CO2 environment. Research shows that trees that grow in higher amounts of CO2 grow more even in lack of water than those in ideal conditions (normal CO2, normal precipitation, normal temperatures). In other words, the trees are not affected by normal limiting factors when there is excess CO2. The question is whether or not there is a noticeable difference in tree ring growth (normal rings-normal conditions or skinny rings-limiting conditions) when comparing it to precipitation and solar data before and since the industrial revolution.
The precipitation and solar data will be monthly values, since a tree does not respond to immediate environmental conditions, but overall average conditions. The tree ring data will be taken from the best ring species in the Oxford area. This will either be conifers or Oak. The tree ring data that I collect will be analyzed by counting and measuring of the tree rings. This will be done using a simple magnifying lens and then counting them. The data will be analyzed using the skeleton plot method. This method involves a standardized x-axis and making long marks on the y-axis for skinny rings and no marks for normal rings. I have been practicing making skeleton plots on a dendrochronology interactive website. The skeleton plot that is compiled from the tree core samples I take will be cross-dated to compile a master chronology of the area. To double-check my findings I will compare to another master chronology from a nearby research area and compare the two. Even though the methods for making skeleton plots may seem a little biased, the overall pattern can be compared to someone else’s skeleton plot very successfully. The Oxford skeleton plot will be converted into a line graph that will show the patterns of growth. This will then be analyzed alongside the precipitation, solar, and carbon dioxide data to see if the theory of accentuated carbon dioxide in trees stands true. References:
Schweingruber, Fritz Hans. Tree Rings: Basics and Applications of Dendrochronology.
Kluwer Academic Publishers, USA, 1989.
Cook, E.R., Kairiukstis, L.A.. Methods of Dendrochronology: Applications in the
Enviornmental Sciences. Kluwer Academic Publishers, USA, 1989.
Kozlowski, T.T.. Tree Growth. The Ronald Press Company, New York, 1962.
Stokes, M.A., Smiley, T.L.. An Introduction to Tree Ring Dating. The University of
Arizona Press, Tucson, 1996.
Web Sites
The Tree Ring Web Pages-Priciples of Dendrochronolgy. http://tree.ltrr.arizona.edu/~grissino/princip.htm
Center for the Study of Carbon Dioxide and Global Change. http://www.co2science.org
Crossdating Tree Rings Using Skeleton Plots. http://tree.ltrr.arizona.edu/skeletonplot/introcrossdate.htm
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